ES2622734B1 - Multi-functional educational electronic device for various branches of engineering - Google Patents

Abstract

Multifunctional educational electronic device for various branches of engineering. The invention relates to a device that, with a series of requirements at the microcontroller and power level, comprises the following subsystems: digital indicator subsystem (provides the microcontroller with light indicators), analog-digital conversion subsystem (transforms to a value of analog voltage in the range 0 - 5v the 8-bit digital value from the microcontroller), RC + RLC subsystem (highly configurable, consists of two electrical circuit meshes that include resistors, capacitors and inductances), external interface subsystem (allows use external devices), servo subsystem (allows control of external radiocontrol servomotors), potentiometer subsystem (consisting of a linear potentiometer), push button subsystem (to enter data or digital information), SRAM subsystem (extends the storage capacity of the microcontroller in memory Static RAM) and miscellaneous subsystem (with components that support other subsystems).

Description

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DESCRIPTION

Electronic educational device with multiple functionality for various branches of the

engineering

Technology Sector

The present invention falls within the sector of electronic training or learning devices, particularly those that allow a user to carry out laboratory practices on concepts of FP level, degree or master in various branches of engineering.

State of the art

The existing electronic circuits for training in various methodologies and concepts related to science and engineering are abundant, although we have not found any that contribute the novelties of the present invention or the same number of functionalities, much less considering the relatively low number of requirements that are established for its implementation.

To structure this section, the following categories of related devices have been distinguished:

A- Electronic boards where a microcontroller can be inserted and that provide a series of circuitry to train in the use of that microcontroller. They are much larger than the microcontroller, usually high cost and can offer a high number of training possibilities. Examples: [23], [24], [25], [26]. However, none have the RC + RLC subsystem proposed in this invention, nor any other subsystems thereof, such as the static RAM or connections with external devices of ± 10v.

B- Electronic boards that extend those based on microcontroller (for example, Arduino / Genuino [1] or PICduino [20]), commonly called shields. They are small in size (approximately the same as that of the board containing the microcontroller), low

cost and quite limited training possibilities, much more than those of the

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category A and of those provided by the present invention. Examples: [27], [28], [29].

C- Training plates for microprocessors (much more powerful than microcontrollers), such as Raspberry Pi [21]. They usually also have very limited functionality, even more than those in category A. For example: [30], [31], [32].

D- Electronic learning kits, not associated with any CPU (microcontroller or microprocessor), which allow to assemble circuits of diverse nature. For example: [33], [34], [35].

Categories C and D, although related to this invention, imply such important differences that they are considered not comparable with it: the microprocessor training plates (C) require a very important auxiliary circuitry to accompany them, something not necessary in the microcontrollers (which increases cost, size and consumption); In addition, being microprocessors electronic devices oriented to the execution of high-level computer programs (operating systems of certain complexity and user applications), they are quite far from what is necessary for learning concepts and methodologies related to engineering such as which are intended here. On the other hand, the electronic learning kits (D) only allow training with very basic concepts, in some cases from other branches of Physics such as Mechanics, and never in a programmable way, which makes them little useful in levels of degree, master or FP when it is required to achieve certain complexity and flexibility in learning and not only stay in the description of the physical concepts (for example, being able to control the systems involved).

With respect to the category A described above, the present invention provides functionalities that are not present in these solutions, can be manufactured at a much smaller size and price but without having lower performance and does not require including a power adaptation system. Among the functionalities of the present invention that are not found in the solutions of this category are: an RC + RLC circuitry configured in a very precise way to do exercises of Automatic Control, Systems Modeling and Data Acquisition without having to add any external device to the invention; a sufficient RAM for the acquisition of data from that and other subsystems (which can be significantly larger than what the integrated microcontrollers usually bring); connections to control and acquire

data from external devices operating in the range of ± 10v (for example, motor drives

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direct current), etc. In addition, the present invention directly reflects the names of the microcontroller pins in their own labeling, so it is very suitable for learning it (it does not hide it, which happens in other solutions of this category).

With respect to category B, the present invention does not provide novelties in price or size, but clearly, in some of its functionalities, which, as in the case of category A, are not found in existing solutions, and also in the own number of functionalities provided at a similar or lower cost and size compared to other shields: control of external devices of ± 10v, systems integrated in the same shield for experiments (RC + RLC circuitry, potentiometers, LEDs, pushbuttons, static RAM for data acquisition, digital-analog converter, serial communications (SPI), servo connectors and their consumption meter), etc. The present invention, if manufactured as a shield, can thus cover learning exercises in a variety of branches of engineering in a single device (Real Time Systems, Electronic Systems, Control Systems, Data Acquisition Systems, Robotics, etc. .), which is far beyond the possibilities of existing solutions in this category.

Finally, it should be noted that the number of related devices that have been patented in this area of the technique are not as numerous as those marketed, due, among other things, to the rise of the open-hardware or open-source hardware movement ( the user can make their own devices because the schematics are available free and publicly [43]), which is being tremendously important in the last decade. The patents that have been identified related to the present invention belong mostly to category D (US4812125A [36], US4213253A [37], US4464120A [38], US5868575A [39], US4315320A [40], US3996457A [41], WO2015112103A1 [ 42]). There is one of category A (CN104424836A [22]), and others difficult to classify, such as CN201765731U [44] and CN103646585A [45], which could be considered in category B because they include expansion plates of a microcontroller board, but also in category A since they also patent the microcontroller board itself (in any case, these two patents in particular achieve functionality comparable to the present invention — not including, in any case, subsystems such as SRAM, RC + RLC or connection with external devices at ± 10v - only when multiple extensions are added to the microcontroller, not just one, and, therefore, at a lower functionality / ratio (cost, size, etc.) than the present invention).

Brief description of the invention

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The present invention comprises a printed circuit board with a large number of educational functionalities that can be manufactured with small size and at low cost. The board includes a series of electronic components so that, once connected to a microcontroller that must meet minimum requirements, specified below, and to a sufficient power supply for its total consumption, it allows the realization of a great diversity of practical exercises for engineering subjects, far superior to that found in existing devices with similar requirements, cost and size.

The invention includes: a labeling that favors the learning of the direct programming of the microcontroller in question by explicitly replicating the names of the signals of this on the board itself (something that not all existing boards do); 8 digital outputs in the 0 / 5v range; 2 digital inputs in the 0 / 5v range capable of receiving digital data or external signals independent of interruption; 1 analog input and 1 output in the range of ± 10v; static RAM of any storage size provided that it has a three-line serial bus (SPI) connection, is compatible with the manufacturing size and has an expected current consumption compatible with the board power supply; 8 LEDs (LEDs); 1 linear manual potentiometer; 1 connector for radio control servomotors commanded by 5v PWM waves in two different formats, in order to cover almost all of those sold; a system for measuring the current consumption of the servo; 3 manual push buttons; and, finally, 1 linear subcircuit, called the RC + RLC subsystem in this invention, built on resistors, capacitors and inductances, of two meshes and highly configurable.

Detailed description of the invention

The present invention comprises a printed circuit board together with electronic components that allow as a whole the realization of a diversity of learning experiences in subjects of various engineering at the level of FP, degree or master. The values of the electronic components have been selected to maximize the functionality of the invention. Its main characteristic and novelty, therefore, consists in its high functionality / cost ratio (and also functionality / manufacturing size), so that at a reduced production cost and size it can offer much wider functionality than other currently existing solutions , and in some of its subsystems, novel. That end has been achieved through the following strategies:

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• The user can easily reconfigure some parts of the circuit according to the learning needs.

• The invention reuses the same subsystems when providing different functionalities.

• It can be manufactured as an extension of existing boards that provide the necessary microcontroller and power supply, as well as possible communications with a personal computer (PC).

• The specific use given to the microcontroller pins that the invention uses is specifically aimed at maximizing the functionalities that can be offered to the user.

The requirements for using this invention are neither numerous nor too demanding; they are the following (see figure 1 for a general display of it):

• Have a board containing a microcontroller that operates at a voltage of 5v on its pins and that allows those pins to be connected to the invention through appropriate connectors. In particular, this microcontroller needs to have the following basic functionalities, all independently (in order to simplify the explanations that follow, all reference to analog inputs, digital outputs, input pins and output pins will be carried out following the nomenclature corresponding to Concrete microcontroller that is presented in the preferred realization section of the invention, without any limitation being deduced since it is intended to exemplify in a generic and valid way for any microcontroller that meets the requirements indicated here):

or 3 analog voltage inputs in the 0 / 5v range equipped with the converter or the necessary analog to digital converters, capable of providing digitized voltages to the microcontroller software with a minimum frequency of 9KHz (therefore, a clock for the microcontroller that allows those frequencies; note that a frequency of 9 kilo-samples per second is very low and can be easily achieved by many microcontrollers equipped with analog-digital conversion). They can share converter between the three analog inputs, and in that case only the indicated conversion frequency is required when each of them will be used

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individually. In the rest of this section, these analog inputs are called, for the purposes of this description, AD1, AD2 and AD5. or 1 digital output capable of generating PWM waves compatible with standard servo motors, that is, that are within the range of 30 to 60Hz frequency and 400 to 3000 microseconds of pulse width, either by hardware when connected to internal timers of the microcontroller or software. In the rest of this section this output is called, for the purposes of this description, PD6. o An internal SPI communications control module [19] that allows the microcontroller to be a server of said bus and has 3 pins: PB5 (SPI-SCK) PB3 (SPI-MOSI) and PB4 (SPI-MISO). In addition, these pins should be able to be used as independent digital inputs or outputs with each other in case the SPI module of the microcontroller is not activated.

or 2 independent input pins of external interruptions to the microcontroller, configurable to trigger the corresponding interruptions by rising or falling edge, and capable of being used as independent digital input or output pins if their functionality as interrupt input is not necessary. These pins are called, for the purposes of the present description, PD2 and PD3. or 8 independent digital output pins for which an unsigned 8-bit number can be sent. For the purposes of the present description, they are referred to as PB2 (bit 0), PB1 (bit 1), PB0 (bit 2), PD7 (bit 3), PD5 (bit 4), PD4 (bit 5), PC4 (bit 6 ) and PC3 (bit 7). or 1 digital output pin that is called, for the purposes of this description, PC0. or 1 digital input pin that produces a reset on the microcontroller when set to a certain state (digital voltage). It is called, for the purposes of this description, RESET.

• Have a power supply for the microcontroller board mentioned at the previous point that can provide at least 500 milliamps at a voltage of 5v, which is regulated, and that is accessible for the invention through appropriate connectors. If you have a source that provides up to 1 amp, the operation of the servomotor will be better in terms of torque, but with 500 milliamps it will also be correct and sufficient for the realization of educational practices.

• Have sufficient hardware and software to be able to program the resident microcontroller on the board mentioned in the first point from a personal computer (PC).

• If the invention is to be used for learning practices with external devices

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(motors, sensors, etc .; see the section of the external interface subsystem), have them. Even without them, the invention provides a significant amount of functionality that can be used.

• If the invention is to be used with external devices that require separate power supply from the microcontroller, dispose of it.

The utilization context thus described is general enough to match a wide variety of existing boards containing microcontrollers (typically 8 or 16 bits, but not only), and can be found in numerous laboratories of universities or vocational training institutes , and also with the majority of households, especially if only the functionalities included in the invention itself are used, without external devices added.

The present invention is characterized by providing the student or student with a variety of very high learning possibilities in relation to engineering studies: Automatic Systems Control [3], Data Acquisition [4], Automation [5], programming of Embedded Systems and Real Time [6], [7], Robotics [8], etc. All these possibilities have in common that the user must program the microcontroller mentioned in the previous requirements through some existing development environment (for example, for the preferred realization presented in this document, the Atmel Studio [9], which It is free, or that provided by Arduino [10], which is also provided), in order to achieve its objectives through the configuration and subsequent control of the different parts of the circuitry proposed here. The functionalities that this invention provides are not available in commercial microcontrollers alone, nor, in their entirety, in the boards that are usually marketed to connect them in order to use them as learning platforms.

More specifically, the invention presented here comprises 9 subsystems that can be used both alone and in various combinations, which gives rise to the high number of possibilities of practical exercises that it allows.

A general block diagram of the invention is shown in Figure 2. In the remainder of this section all subsystems are described in detail, as well as their particular requirements, their respective functionalities and their possible combinations.

Digital Indicators Subsystem

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Figure 3 shows this subsystem. This provides the microcontroller with light indicators, useful for depuration, data visualization and other purposes. In particular, it allows programming from the microcontroller of 8 independent binary light signals (ON / OFF) in positive logic.

This subsystem has the following requirements with respect to the microcontroller and the rest of the invention (taken from the requirements listed at the beginning of this section for the complete invention; to simplify those referring to the power supply or the presence of the microcontroller itself are not indicated):

• 8 independent digital output pins, designated, for the purpose of this description, PB2 (bit 0), PB1 (bit 1), PB0 (bit 2), PD7 (bit 3), PD5 (bit 4), PD4 (bit 5), PC4 (bit 6) and PC3 (bit 7).

The usefulness of this subsystem is diverse:

• Learning the programming of digital output ports of a microcontroller, for example in subjects related to Embedded Systems or Real Time.

• Trace indicators and data visualization for debugging programs. This is useful in any practice that can be done with the invention.

• Learning of programming of embedded systems: if the realization of the invention uses for the so-called pins, for the purposes of the present description PB2, PB1, PB0, PD7, PD5, PD4, PC4 and PC3 more than one port of the microcontroller, the programmer You must configure the indicators to the desired value without modifying the others, which requires relatively complex bit manipulation operations.

The digital signals that this subsystem receives, from the microcontroller, are the same as those received by the DAC subsystem explained later, so we save 8 additional digital bits in the invention, reducing its cost and size. This is one of the examples of reuse of subsystems and elements in the present invention.

The digital signals will be conveniently protected with resistors so that the total current consumption in case all the indicators light up simultaneously is assumable by the power supply. For this, LEDs of low consumption and high luminosity are considered.

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Analog-Digital Conversion Subsystem (DAC)

Many microcontrollers do not have analog outputs, so it is difficult to control electronic devices directly. The present invention includes a DAC subsystem (see Figure 4) in charge of transforming to an analog voltage value between 0v and 5v, in a linear way, the 8-bit digital value existing in the same microcontroller pins that act as subsystem inputs of digital indicators (ie PB2, PB1, PB0, PD7, PD5, PD4, PC4 and PC3). This gives a resolution of 5/256 = approximately 20mV at this analog output.

This subsystem has the following requirements regarding the microcontroller and the rest of the invention:

• 8 independent digital output pins, designated, for the purpose of this description, PB2 (bit 0), PB1 (bit 1), PB0 (bit 2), PD7 (bit 3), PD5 (bit 4), PD4 (bit 5), PC4 (bit 6) and PC3 (bit 7).

• 1 digital output pin called, for the purposes of this description, PC0.

• The miscellaneous subsystem, explained below, which provides a specific power supply of + 15v.

The invention will allow the analog output voltage to be frozen for a certain time by means of the digital output signal called, for the purposes of the present description, PC0 of the microcontroller (otherwise the conversion will be carried out continuously over time). This allows to avoid undesirable and abrupt changes in the analog output while some of the digital input bits of the subsystem have not yet had time to be updated.

The main utility of this DAC subsystem is that already mentioned to control external systems, for example DC motors (conveniently powered separately) or LEDs (varying their luminosity), which fits perfectly in subjects related to Automatization, Robotics, Automatic Control or Embedded Systems, but, in addition, the output is also connected to the RC + RLC electrical subsystem, described below (the DAC subsystem is necessary for the RC + RLC), which allows a device of certain complexity to be controlled. This combination of subsystems (DAC and RC + RLC) allows the realization of Automatic Control practices without adding any more device to the microcontroller (typically DC motors, expensive, expensive and that need additional sources of energy), as will be described in the next section, reducing like this

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enormously the cost of necessary equipment in teaching laboratories.

RC + RLC subsystem

Figure 5 shows the block diagram of this subsystem, perhaps the most complex, novel and with more possibilities of realization of learning practices of the entire invention.

This subsystem has the following requirements regarding the microcontroller and the rest of the invention:

• The analog output given by the DAC subsystem, described above.

• Optionally, the SRAM subsystem (see below).

• 1 analog voltage input, called, for the purposes of this description, AD2, in the range 0 / 5v, equipped with the necessary analog-to-digital converter capable of providing digitized voltages to the microcontroller software with a minimum frequency of 9KHz ( therefore, a clock for the microcontroller that allows those frequencies).

This subsystem consists of two electric circuit meshes with linear elements [13]: the RC mesh consists of a resistor and a capacitor in series, so if the voltage in the resistor is considered as input and the voltage in the capacitor as output the behavior of a first-order linear system is obtained; The RLC mesh consists of a resistor, an inductance and a capacitor in series, so if the voltage in that resistance is considered as input and that of the capacitor is obtained, the behavior of a second-order linear system is obtained. Within the scope of electrical circuits, these two meshes are the simplest way to obtain first and second order systems.

Each of these meshes individually has great utility when it comes to practice modeling of LTI systems (linear and time-invariant). For this purpose, this subsystem must be combined with the analog output of the DAC subsystem, which can be easily connected (via a switch or selector) to the desired mesh according to educational needs, and the output voltage of that mesh must be sampled , saving the values in the static RAM of the invention (subsystem described below). One of the novelties of this subsystem in the field of educational devices is that the specific values for the electrical components of both meshes, especially those of the

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The second inductance has been calculated so that the sampling of the output of any of them can be done properly with a microcontroller that has a minimum analog to digital conversion frequency of 9KHz (very slow), as explained in the requirements of the invention at the beginning of this section, that is, with a number of samples per unit of time large enough to be able to appreciate the main characteristics of the mesh behavior and that aliasing does not occur [14]. Because the electrical circuits usually have very fast temporal responses, there are not too many possibilities of values for the electrical components of the meshes that allow to obtain such slow responses. The following have been the components chosen for the first mesh: R = 100 ohms, C between 2pF and 21.7pF (selectable as explained below); for the second mesh: R between 0 and 500 ohms (linearly variable), L = 47mH and C = 1pF.

In addition to the modeling and temporal description of first and second order systems, both meshes allow the realization of Automatic Control practices, that is, the user can vary the analog signal produced by the DAC based on the mesh output, thus regulating its behavior, which constitutes another novelty contributed by this subsystem in the field of educational devices. For this purpose it is important to verify that the output of the DAC will be between 0 and 5v, and that both meshes have a unit gain, so that their outputs could be greater than 5v even if the DAC only reaches 5v. Therefore, it should be considered that these outputs can be saturated in 5v (not to saturate them, it is enough to make the DAC produce less than 5v).

The RC mesh, as indicated above, must be configured manually using a pair of switches. These serve to select a capacitor value from a set of 4 different values: 2pF, 6.7pF, 17pF or 21.7pF, so you can set different time constants for the system and thus vary its behavior, within which the Microcontroller will be able to sample, obtaining various first-order responses.

The RLC mesh must also be configured, with the same objective: its resistance is variable (it is a potentiometer) so that the user can change his behavior comfortably.

In addition to operating separately, so that the user can choose which mesh to use (but only one at a time), both meshes can be interconnected, if one wishes not to use them individually, so that they constitute a third-order electrical system, what constitutes the third important novelty contributed by this subsystem in the field of educational devices. Thus, the first mesh would become a stage before the second. This is done using selectors 1 and 2 (see Figure 5 again). In its third-order system format, being able to change the value of the first mesh capacitor (RC) is very important for

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the realization of educational practices, since it allows to vary the behavior of the output of the system, since it closely resembles a second order (small capacitor values) until the behavior of the third order (larger capacitor values) appears. This allows the realization of systems approach practices by identifying dominant poles [3].

Finally, it should be noted that the first mesh will have at its entrance a buffer that will receive the output signal from the DAC and replicate it without changes. This buffer is necessary to provide the power required by both meshes (in case they are connected in series to form the third order) or by any of them separately; in particular, it will give a minimum of 100 mA.

Also, the final output, which can be sampled by the microcontroller, must be selected to be that of the first mesh, the second or the buffer itself without going through any mesh, again using selectors 1 and 2. The option to be that of the buffer itself allows the invention to be calibrated, in particular to which analog voltages correspond to the digital value sent to the DAC and to which digital values the analog value received by the buffer corresponds. In addition, it will be protected by two cutting diodes so that voltages above 5v or below 0v do not reach the analog input of the microcontroller.

In summary, this subsystem, thanks to its great flexibility, the careful choice of the electronic components and the microcontroller pins involved, and their combination with other subsystems of the same invention (the DAC subsystem mandatory, the RAM subsystem of optional), it provides the possibility of carrying out a numerous and innovative set of engineering learning practices, with only two selectors and a variable resistance as configuration mechanisms as a minimum configuration mechanism, and at an exceptionally reduced cost:

• Modeling, identification and study of the temporal response of first order, second order and higher order LTI systems in subjects related to Automatic Control and Systems Engineering, with a variety of manually selectable behaviors.

• Data acquisition and sampling of the output of electric LTI systems by means of a microcontroller, for subjects related to Automatic Control, Data Acquisition and Real Time Systems.

• Study of the stability and error in steady state of LTI systems, as well as their transitory behavior by means of roots, for subjects related to Automatic Control.

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• Implementation of different types of linear and non-linear control laws for LTI systems, in subjects related to Automatic Control, Real Time Systems and Embedded Systems.

There is currently no microcontroller extension circuitry in the market with these benefits in terms of learning and with this cost (and size) of fabrication.

External interface subsystem

This subsystem is shown as a block diagram in Figure 6. It is the part of the invention that allows the use of additional external devices when desired (which does not have to be necessary, as already described) for the realization of a number in principle unlimited new practices. This functionality is also not usually present in existing educational devices (and, if found, is not accompanied by the rest of the functionalities of the present invention). For this, an electrical input and an output interface have been designed that operate in the voltage range of ± 10v. There is a great diversity of external devices that work analogically in that range (or in ranges contained therein): motors, sensors, indicators and other electronic circuitry. This subsystem allows to generate an analog signal of ± 10v towards those devices and, simultaneously, to receive another signal in the same voltage range from them, so it is possible to close a control loop that has been implemented in the microcontroller. Keep in mind that both signals do not provide power, so the external device connected to the invention must be powered separately.

This subsystem has the following requirements regarding the microcontroller and the rest of the invention:

• The analog output given by the DAC subsystem, described above.

• The miscellaneous subsystem, described below.

• Optionally, the SRAM subsystem.

• 1 analog voltage input, called, for the purposes of this description, AD1, in the range 0 / 5v equipped with the necessary analog-to-digital converter capable of providing digitized voltages to the microcontroller software with a minimum frequency of 9KHz (per therefore, a clock for the microcontroller that allows those frequencies).

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The generated output signal is produced from the analog output of the DAC subsystem, which is necessary whenever this external interface subsystem is used (another example of subsystem reuse for various purposes in the present invention). The output of the DAC subsystem is passed through a first buffer to decouple the DAC from the interface subsystem, and then through an operational amplifier that scales and displaces it to obtain the desired range of ± 10v (for this a reference voltage will be available in the same invention). On the other hand, the ± 10v signal from external devices is passed through two operational amplifiers that scale and move it to the range of 0v to 5v, which enters the analog pin called, for the purposes of this description, AD1 of the microcontroller, which the invention will have conveniently protected (a reference voltage is also needed here).

To reduce the cost of the invention, both paths, input and output, can reuse the same reference voltage of 1.25v for their scaling and displacement calculations; in that case the output of the DAC, although it can be between 0v and 5v, should be limited by the user to the range of 0v to 2.5v (from 256 to 128 possible analog voltages), since higher voltages will saturate the signal produced towards the outside at + 10v. If the invention were implemented with two different reference voltages, this would not happen.

It should be noted that the input signal received by the part of the subsystem responsible for transferring from ± 10v to 0v-5v (input path) shares the pin called, for the purposes of this description, AD1 with another signal produced by the subsystem servo, described below; To select which one you want to read, the user has a manual switch. This has been designed like this because the practices that can be performed with the external interface subsystem do not need the servo subsystem (both do not make much sense in combination for educational practices), so both signals are not going to be read at the same time.

Finally, both voltage conversion paths need a power supply of ± 15v. This is produced by the miscellaneous subsystem described below, which, like the DAC, is essential for this external interface subsystem to work. To produce this voltage, the invention uses only the 5v power supply that is available according to the requirements explained at the beginning of this section.

In short, this external interface subsystem allows to work, if desired, with a very high number of additional devices to the invention, and to perform both modeling and identification practices thereof (optionally using the SRAM subsystem for the acquisition of

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data) as direct control through the microcontroller. It also allows the realization of experiences of Data Acquisition, Programming of Embedded Systems, Real Time Systems, Robotics, etc.

Servo subsystem

Figure 7 shows the diagram of this subsystem, in charge of allowing the control of external radiocontrol servomotors [16] (not included in the invention) by means of a digital output pin of the microcontroller, specifically the so-called pin, for the purpose of present description, PD6, whereby a PWM signal can be generated as set forth in the microcontroller requirements specified at the beginning of this section.

This subsystem has the following requirements regarding the microcontroller and the rest of the invention:

• 1 analog voltage input, called, for the purposes of this description, AD1, in the 0 / 5v range equipped with the necessary analog-to-digital converter capable of providing digitized voltages to the microcontroller software with a minimum frequency of 9KHz (therefore , a clock for the microcontroller that allows those frequencies).

• 1 digital output called, for the purposes of this description, PD6 capable of generating PWM waves compatible with standard servomotors, that is, within the range of 30 to 60Hz frequency and 400 to 3000 microseconds of pulse width, and either by hardware when connected to internal microcontroller timers or by software.

• Optionally, the SRAM subsystem.

The novelty that this subsystem provides with respect to existing educational solutions is its use of the PWM wave to control a great diversity of components (normally only radio control servos can be controlled), as well as the possibility of monitoring their electrical consumption; Both are described in more detail below.

This subsystem receives the PWM signal from the microcontroller and uses it for two purposes: first, to blink an LED, which allows you to perform timer programming practices and even use that LED as a trace and depuration indicator, added at 8 LEDs of the digital indicator subsystem already explained; secondly, and principally, to send the PWM simultaneously to a series of physical connectors where various

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types of servomotors. The invention provides three different connectors for this purpose, since with that number all the devices that can be controlled with a PWM are covered in practice: one for servomotors using GVS (ground-feed-signal) format connectors, another for servo motors using the VGS connector format, and the latter for general loads that can receive a power signal commanded by a PWM. The first two connectors cover almost all connector formats of radiocontrol servomotors in the market. The third allows the direct connection of any load other than a servomotor (motors, bulbs, etc.) that can be controlled with a switched signal (PWM) on a power rail, up to a maximum of the amperage that the source of power can provide. feed using the invention (for example, 1A). Radiocontrol servomotors have a similar power control system inside, so they do not need this connector; having it allows you to perform additional practices of Electronics, Automatic Control, etc.

This subsystem also has a part in charge of filtering the 5v power supply that it sends to the servo; Its purpose is to prevent the propagation of noise and voltage drops between the servo itself and the invention (servo motors, such as electromechanical devices, are prone to cause such problems). The invention allows conventional size servos to be fed directly from the microcontroller board. In any case, the subsystem includes a rearmable fuse in the servo feed path for exceptional situations.

Finally, as already mentioned, this subsystem also has, in a new way, a servo current consumption sensor, located in the power supply path, and implemented by means of a small value shunt resistor plus a voltage amplifier . This sensor provides an analog voltage between 0v and 5v that is proportional to the current that the servo is consuming at all times (considering that the maximum is approximately 1A), and, therefore, also proportional to the torque it is exerting. The data thus acquired can be stored over time using the SRAM subsystem. To acquire them, the analog signal of this sensor can be connected to the pin called, for the purposes of this description, AD1 (analog input of the microcontroller) mentioned in the requirements of the invention at the beginning of this section, using for this purpose a switch that select either this or the input signal of the external interface subsystem. The availability of the servo current consumption signal allows the realization of practices on Real Time Systems, Embedded Systems, Automatic Control Systems,

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Data Acquisition, Robotics (robots with legs, for example), etc.

Potentiometer Subsystem

This simple subsystem is shown in Figure 8: it is a linear potentiometer that allows the user to manually set the value of a resistor and, through it, that of a voltage divider, thus generating a signal of analog voltage between 0v and 5v that is connected to the pin called, for the purposes of this description, AD5 which is established as a requirement of the microcontroller (analog input). This subsystem only needs the 5v power supply that will be connected to the invention and includes protections against short circuits. The potentiometer in question will be of small size so as not to harm the size factor of the invention, and short mast so as not to overhang the entire circuit.

This subsystem has the following requirements regarding the microcontroller and the rest of the invention:

• 1 analog voltage input, called, for the purposes of the present description, AD5, in the 0 / 5v range equipped with the necessary analog to digital converter capable of providing digitized voltages to the microcontroller software with a minimum frequency of 9KHz (therefore , a clock for the microcontroller that allows those frequencies).

The usefulness of this subsystem is to perform simple practices of data acquisition, programming of embedded systems, automatic control and automation (such as analog input or system configuration parameter), etc., as well as being able to implement complex practices of Easier way by simplifying some analog input, to be able to be replaced this by the potentiometer.

Push Button Subsystem

This subsystem is also very simple, as seen in Figure 9. The invention includes here 3 buttons that the user can use to enter data or digital information. They are connected to three digital inputs of the microcontroller, specifically those that are called, for the purposes of this description, PB4, PB3 and PD2 in the requirements specification. It should be noted that the first two pins are shared with the SRAM subsystem in a mandatory manner; therefore, they are conveniently protected against unwanted short circuits or interference between both subsystems in the present invention.

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This subsystem has the following requirements regarding the microcontroller and the rest of the invention:

• 2 digital input signals named, for the purposes of this description, PB3 and PB4 independent of each other.

• 1 external interrupt input pin called, for the purposes of this description, PD2.

The three buttons can be used in a multitude of practices, as an indication by the user that the system can move to another state, as a signal for the beginning or end of practices dealing with other subsystems, or as a simple data entry. To read the status of any of them, the corresponding microcontroller registers can be accessed, that is, by active waiting, but, in addition, the button associated to the so-called pin, for the purpose of this description, PD2 can be used as an interruption input external, since in the requirements that have been specified that pin also has the functionality of interruption. Therefore, that button can trigger events. Its usefulness is thus extended to practices of Programming of Embedded Systems and Real-Time Systems, among others.

SRAM subsystem

The invention includes a subsystem that allows to expand the storage capacity in RAM of the microcontroller, which is usually too low to acquire a relevant volume of data. This is also a novelty of the present invention with respect to the existing solutions in the field of educational devices. Figure 10 shows how this subsystem provides the board with this additional static RAM. We have selected static memory to avoid the need for additional circuitry or software that has to deal with the periodic refreshment of its content [18]. Its storage size can be any that suits the fabrication of the invention and the use of this subsystem for data collection tasks.

This subsystem has the following requirements regarding the microcontroller and the rest of the invention:

• An internal SPI communications control module [19] that allows the microcontroller to be a server of said bus and that has 3 so-called pins, for the purposes of this description, PB5 (SPI-SCK) PB3 (SPI-MOSI) and PB4 (SPI-MISO).

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• 1 digital output pin called, for the purposes of this description, PD2.

This subsystem can be used in a variety of practices, especially those that involve data acquisition (some already mentioned in previous sections, related to Automatic Control, for example), but also for the realization of two types of particular exercises, which increases even more the educational functionalities of the invention: the study of the real-time aspects of data acquisition, since that memory exhibits specific and measurable delay times by the microcontroller during its operation, and practices it with the communications bus SPI series for embedded systems, which is what the invention uses to communicate the microcontroller with memory. Both studies have a perfect place in subjects related to Real Time Systems and Recessed Systems programming.

The invention is designed so that communications of the SRAM subsystem with the microcontroller can be disabled by means of the pin called, for the purposes of this description, PD2 of digital output thereof, so that the so-called pins can be reused, for the purpose of present description, PB4 and PB3 for the push button subsystem, without problems of collision with the SPI bus while the SRAM is disabled (the data stored in it is not lost because of it).

The SRAM only needs the 5v power supply available for the invention and a short circuit protection resistors.

Miscellaneous Subsystem

The present invention is completed with some more components that we have grouped into a miscellaneous subsystem, which support others in various ways. This subsystem includes (see Figure 11):

• A filtering circuit that avoids noise and voltage drops in the feed that the invention uses. The output of this circuit is the 5v (and the earth) that feed the rest of the subsystems described above. It also has a resettable fuse for exceptional power consumption situations, as well as a power supply LED. The filter is an essential element of the invention, while the resettable fuse and the indicator LED are optional.

• A DC / DC converter that transforms the 5v of the previous filter into a power supply

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± 15v, necessary for the external interface subsystem, as discussed above.

• A button that activates the RESET signal of the microcontroller. This button is necessary only when the invention is carried out in such a way that it conceals the microcontroller and avoids the possibility of restarting it (as in the preferred embodiment, described below).

• A replica of the names of the pins that the microcontroller provides to the invention (according to the requirements established at the beginning of this section), according to the manufacturer's nomenclature. This facilitates the realization of practices of programming of embedded systems with this microcontroller.

• An electrical bridge that connects, conveniently protected (with a resistor), the so-called pins, for the purposes of this description, PD6 and PD3 that the microcontroller must have according to our requirements. As previously mentioned, the first one is a digital output pin and also the pin that provides the PWM output for the servomotor subsystem, while the second is a pin that receives one of the external interrupts of the microcontroller. The reason for reusing both to interconnect them in this way is to enable the possibility that the user can detect through this interruption the descents or rises of the PWM signal, used mainly in the servo subsystem, and act accordingly. This is useful in practices of Embedded Systems, Automatic Control, Data Acquisition and Real Time.

Description of the figures

Fig. 1. Deployment of the invention for use.

Fig. 2. General block diagram of the invention.

Fig. 3. Subsystem of digital LED indicators.

Fig. 4. Digital-analog conversion subsystem that receives the same digital data as the LED indicator subsystem, plus an enable signal, and converts the binary numerical data represented by the former into a low power analog voltage.

Fig. 5. Block diagram of the RC + RLC subsystem, which receives the analog signal produced by the DAC subsystem and produces another analog signal that can be read on the analog input pin AD2 of the microcontroller. RC and RLC meshes are internally configurable

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by means of two switches and a potentiometer, respectively, while the interconnections between them are defined by selectors 1 and 2.

Fig. 6. Interface subsystem with external devices. It receives the power available to the invention and the output signal of the DAC subsystem, and produces a signal equal to this but in the range ± 10v for external devices. You can also receive a ± 10v signal from them and transfer it to the analog input AD1 of the microcontroller.

Fig. 7. Control subsystem of radiocontrol servomotors and loads that need power. It receives a PWM digital signal (0-5v) from the PD6 pin of the microcontroller, and can use it to: turn on and off an LED, control servos with G-V-S or V-G-S connectors, and control loads that require power. The power supply of the connectors is conveniently filtered against noise and consumption peaks, and can be measured by the analog input AD1 of the microcontroller.

Fig. 8. Manual potentiometer subsystem. The user can change his position, which is reflected in an analog voltage that can be read by the AD5 input of the microcontroller.

Fig. 9. Push button subsystem. Each one is independent of the others and produces a voltage of 5v if it is pressed (0v in case it is not) on a digital input pin of the microcontroller.

Fig. 10. SRAM subsystem for external data storage. The microcontroller communicates with it through its own SPI bus plus an enable signal.

Fig. 11. Miscellaneous subsystem of the invention. This includes, from left to right, a filter for noise in the power supply that reaches the invention, a light indicator of said power supply, a push button that allows the microcontroller to be reset, a direct replica of all the connectors of the microcontroller board that are available for such use and an interconnection of the PD6 pin with the PD2 pin of the microcontroller for the realization of some interruption exercises.

Fig. 12. Realistic simulation of the preferred embodiment, where its physical appearance is appreciated. This PCB will be connected to an Arduino / Genuino UNO board (not shown) using the male pins that are observed on the sides of its lower part, so it has the same dimensions as this: 68.6 mm x 53.4 mm [2].

Fig. 13. General schematic of the preferred embodiment and of the part of the miscellaneous subsystem that has nothing to do with the feeding of the invention. This figure shows the interconnections of the different subsystems (shown in the following figures), as well as those between them and the ATmega328P microcontroller of the Arduino / Genuino UNO board.

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Fig. 14. Schematic with the preferred realization of the LED indicator subsystem.

Fig. 15. Schematic with the preferred embodiment of the digital-analog conversion subsystem.

Fig. 16. Schematic with the preferred embodiment of the RC + RLC subsystem.

Fig. 17. Schematic with the preferred embodiment of the interface subsystem with external devices.

Fig. 18. Schematic with the preferred embodiment of the control subsystem of radio control servomotors and loads that need power.

Fig. 19. Schematic with the preferred embodiment of the manual potentiometer subsystem.

Fig. 20. Schematic with the preferred embodiment of the push-button subsystem.

Fig. 21. Schematic with the preferred embodiment of the SRAM subsystem.

Fig. 22. Schematic with the preferred embodiment of the part of the miscellaneous subsystem related to the feeding of the invention.

Fig. 23. Top track face of the PCB for the preferred embodiment.

Fig. 24. Lower track face of the PCB for the preferred embodiment.

Fig. 25. Simulated aspect of the upper face of the PCB for the preferred embodiment, once the components are welded, where the labeling designed for the invention can be seen, which on the side connectors replicates the name of the ATmega328P microcontroller pins, something not available on the Arduino / Genuino UNO board.

Fig. 26. Simulated appearance of the underside of the PCB for the preferred embodiment, once the components are welded. The connection pins connecting the invention with the Arduino / Genuino UNO board are observed pointing out the image.

Preferred embodiment of the invention

The constitution and characteristics of the invention will be better understood with the help of the

following description of examples of realization, it being understood that the invention does not remain

limited to these embodiments, but the protection covers all those embodiments

alternatives that may be included within the content and scope of the claims.

Likewise, this document refers to various references as prior art,

understood to be incorporated by reference the content of all these documents, in order to

offer a complete description of the state of the art in which it is presented

invention fits. The terminology used below is intended to describe

from the example of embodiment that follows and should not be construed as limiting or

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restrictive

In this section we describe a preferred form of implementation of the invention. In this we choose the Arduino / Genuino UNO board [2] as the microcontroller container, which will therefore be the Atmega328P of Atmel [11]. In this case the invention consists of an Arduino / Genuino extension plate (that is, a shield), so it has the same dimensions as this: 68.6 mm x 53.4 mm [2]. In this printed circuit board (PCB) the necessary components for the realization of the invention are soldered, finally obtaining a circuitry that is manually connected to the Arduino / Genuine UNO board by a series of pins (see figure 12). The power supply of the invention comes from that received by the Arduino / Genuino UNO board, which may, in turn, come from the same PC from where it is programmed (via USB, which gives 5v and up to 500 mA), or either from an external power supply between 7v and 12v connected to the Arduino / Genuino UNO board through its power input jack. The Arduino / Genuino UNO board has linear regulators so that in the latter case the requirements specified for the invention in terms of power are met (in the first case the USB itself already has a regulated voltage).

As already explained, the present invention provides functionalities not currently available in the identified existing devices, such as the RC + RLC circuitry, the SRAM or the ± 10v connections with external devices.

Each subsystem of those explained in detail in the previous section corresponds in this preferred embodiment with an electronic circuit. Figures 13 to 22 are the schematics of said electronic circuits. These schematics show the values of the electronic components chosen for it, which comply with everything specified in general above, as well as their specific models in cases where the specific model or part is important to comply with the description of the invention and / or get a good functionality / cost ratio.

In particular, the functionality of the DAC subsystem is provided by the TLC7524 digital-analog conversion integrated circuit [12] plus a 2.5v voltage reference that can be easily obtained from the 5vs that feed the invention; In the RC + RLC subsystem, the first mesh has at its input a TLV4111 buffer [15] that receives the output signal from the DAC and replicates it, which can give a maximum of 150mA, thus fulfilling the requirements of the invention; For the potentiometer subsystem we have chosen the potentiometer model RK09K1110A0J from the manufacturer ALPS [17].

Figures 23 and 24 show the faces of upper and lower tracks respectively of the PCB

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of the preferred realization, as they would once be ready for fabrication. Likewise, Figures 25 and 26 show, in a simulated way, how both faces would be with the welded components, which also serves to appreciate the labeling designed for the invention, which in the lateral connectors replicates the name of the ATmega328P microcontroller pins, something not available on the Arduino / Genuino UNO board and that can make it difficult to learn from said controller, as previously mentioned.

References

[1] Arduino (2016). Arduino / Genuino official website,
https://www.arduino.cc/. Retrieved on September 12, 2016.

[2] Arduino (2016). Official website of the Arduino / Genuino UNO model,
https://www.arduino.cc/en/Main/ArduinoBoardUno. Retrieved on September 12, 2016.

[3] Nise N.S. (2011). Control Systems Engineering, Sixth Edition, Wiley, ISBN 978-0-47064612-0.

[4] Suarez C. (ed.) (2015). Data Acquisition Handbook, ML-books International, ISBN 9781632401328.

[5] Nof S.Y. (ed.) (2009). Handbook of Automation, Springer, ISBN 978-3540788300.

[6] Zurawski R. (ed.) (2005). Embedded Systems Handbook, CRC Press.

[7] Wellings A., Burns A. (2009). Real-Time Systems and Programming Languages: Ada, RealTime Java and C / Real-Time POSIX, Addison-Wesley.

[8] Siciliano B. (ed.) (2008). Handbook of Robotics, Springer.

[9] Atmel (2016). Official website of the Atmel Studio development environment,

http://www.atmel.com/tools/atmelstudio.aspx. Retrieved on September 12, 2016.

[10] Arduino (2016). Official website of Arduino development software.
https://www.arduino.cc/en/Main/Software. Retrieved on September 12, 2016.

[11] Atmel (2016). Official website of the ATmega328P microcontroller,
http://www.atmel.com/devices/atmega328p.aspx. Retrieved on September 12, 2016.

[12] Texas Instruments (2016). DAC TLC7524 specification sheet. Available publicly at
http://www.ti.com/lit/ds/slas061d/slas061d.pdf. Retrieved on September 12, 2016.

[13] Nilsson J.W., Riedel S. (2014). Electric circuits, Tenth edition, Pearson, ISBN 9780133760033.

[14] Oppenheim A.V. (2008). Signals and Systems, Second edition, PHI, ISBN 9788120312463.

[15] Texas Instruments (2016). TLV4111 buffer specification sheet. Available publicly at
http://www.ti.com/lit/ds/symlink/tlv4111.pdf. Retrieved on September 12, 2016.

[16] Scarpino M. (2015). Motors for Makers: A Guide to Steppers, Servos, and Other Electrical Machines, Que Publishing, ISBN 978-0134032832.

[17] Alps (2016). Official website of the potentiometer RK09K1110A0J. Available publicly at
http://www.alps.com/prod/info/E/HTML/Potentiometer/RotaryPotentiometers/RK09K/RK09K 1 110A0J.html. Retrieved on September 13, 2016.

[18] Rajput S. (2013). CMOS SRAM Memory Chip Design: High Speed and Low Power,

Lambert Academic Publishing, ISBN 978-3-659-32037-8.

[19] Frenzel L. (2015). Handbook of Serial Communications Interfaces: A Comprehensive Compendium of Serial Digital Input / Output (I / O) Standards, Newnes, ISBN 978-0128006290.

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10

fifteen

twenty

25

30

35

40

Four. Five

fifty

[20] Fritzing (2015). PICduino official website.
http://fritzing.org/projects/picduino. Retrieved on September 20, 2016.

[21] Raspberry Pi Foundation (2016). Raspberry Pi official website.

https://www.raspberrypi.org/. Retrieved on September 20, 2016.

[22] Ma-Wang (2013). Electronic technology experimental box for classroom teaching. Code CN104424836A.

[23] Reach Electronics (Kickstarter) (2014). Portable Dual Arduino (TM) Micro XPlorerBoard. Available in
https://www.kickstarter.com/projects/1576747460/portable-dual-arduino-micro- xplorerboard? lang = es. Retrieved on September 20, 2016.

[24] Parallax Inc. (2014). Board of Education Shield. Available in

https://www.parallax.com/product/35000. Retrieved on September 20, 2016.

[25] Velleman Kits (2003). PIC Programmer & Experiment Kit K8048. Available in
http://www.apogeekits.com/pic_programmer_k8048.htm. Retrieved on September 20, 2016.

[26] Parallax Inc. (2014). Basic STAMP Discovery Kit. Available in

https://www.parallax.com/product/27807. Retrieved on September 20, 2016.

[27] Dilligent Inc. (2014). Analog Shield Available in
http://store.digilentinc.com/analog- shield-high-performance-add-on-board-for-the-arduino-uno /. Retrieved on September 20, 2016.

[28] Visgence Inc. (2013). Power DAC Shield Available in
https://www.tindie.com/products/visgence/power-dac-shield/. Retrieved on September 20, 2016.

[29] Numato Labs. (2015). Digital and Analog IO Expander Shield. Available in
http://numato.com/digital-and-analog-io-expander-shield/. Retrieved on September 20, 2016.

[30] Gertboard (2012). Gertboard for Raspberry Pi. Available in
http://en.farnell.com/gertboard/gertboard/assembled-gertboard-for-raspberry/dp/2250034. Retrieved on September 20, 2016.

[31] Piface (2013). Piface I / O board for Raspberry Pi. Available in
http://es.farnell.com/piface/piface-digital/io-expansion-board-for-raspberry/dp/2218566. Retrieved on September 20, 2016.

[32] University of Entre Rios (2015). Educational electronic board. News published in
http://www.elonce.com/secciones/sociedad/407429-en-la-uner-desarrollan-una-placa-electrnica- educativa / .htm. Retrieved on September 20, 2016.

[33] SparkFun (2014). SparkFun inventor kit. Available in
https://www.sparkfun.com/products/12060. Retrieved on September 20, 2016.

[34] Cebek (2001). Electronic trainers. Available in
http://www.electan.com/kits- educative-cebek-coaches-electronica-c-

320_315.html? OsCsid = 7fo1vh793l5f8qced2i3jno0m4. Accessed on September 20, 2016.

[35] Snapcircuits (2016). Electronic trainers. Available in
http://www.snapcircuits.net/. Accessed on September 20, 2016.

[36] Sony Corp. (1985). Interactive teaching apparatus. Code US4812125A.

[37] NIDA Corp. (1978). Electronic teaching and testing device. Code US4213253A.

[38] Jensen K. (1982). Simulator systems for interactive simulation of complex dynamic systems. Code US4464120A.

[39] Kuczewski R.M. (nineteen ninety six). Cooperative / interactive learning system for logic instruction. Code US5868575A.

[40] Gabriel E.Z. (1979). Educational analog computer laboratory. Code US4315320A.

[41] Gabriel E.Z. (1974). Electronic analog computers. Code US3996457A.

[42] Durukan C. (2014). Training and experiment system supported by an animation based full

simulation method Code WO2015112103A1.

[43] Pearce J.M. (2013). Open-Source Lab: How to Build Your Own Hardware and Reduce Research Costs. Elsevier, ISBN 9780124104624.

[44] Dan (2010). Open and modular singlechip teaching and learning experimental device. 5 Code CN201765731U.

[45] Zhan Yufu (2014). Embedded single-chip microcomputer application technology project training system. Code CN103646585A.

Claims (26)

5 10 fifteen twenty 25 30 1. Multiple functional electronic educational device for various branches of the engineering that requires • Have a board containing a microcontroller that operates at a voltage of 5v on its pins and that allows these pins to be connected to the educational electronic device through appropriate connectors, said microcontroller having: • 3 analog voltage inputs in the 0 / 5v range equipped with the necessary analog or digital converter or converters, capable of providing digitized voltages to the microcontroller software with a minimum frequency of 9KHz; • 1 digital output capable of generating PWM waves within the range of 30 to 60Hz frequency and 400 to 3000 microseconds of pulse width; • An internal SPI communications control module that allows the microcontroller to be a server of said bus and that has 3 pins that should be able to be used as independent digital inputs or outputs with each other in case the SPI module of the microcontroller is not activated; • 2 independent interrupt input pins to the microcontroller, configurable to trigger the corresponding interruptions per rising or falling edge, and capable of being used as independent digital input or output pins; • 8 independent digital output pins for which an unsigned 8-bit number can be sent; • 1 digital output pin; Y • 1 digital input pin that produces a reset on the microcontroller when set to a certain state (digital voltage); • Have a power supply for the microcontroller board mentioned in the previous point that can provide at least 500 milliamps at a voltage of 5v, which is regulated, and that is accessible to the educational electronic device through appropriate connectors; Y • Have sufficient hardware and software to program the 5 10 fifteen twenty 25 30 microcontroller resident on the board mentioned in the first point; characterized in that it comprises the following subsystems: • Digital indicators subsystem, which provides the microcontroller with luminous indicators, useful for debugging, data visualization and other purposes, and which allows programming from the microcontroller of 8 independent binary light signals (ON / OFF) in positive logic; • Digital-analog conversion (DAC) subsystem, which transforms to an analog voltage value in the range 0 - 5v, in a linear fashion, the 8-bit digital value existing on the same microcontroller pins that act as inputs of the subsystem of digital indicators; • RC + RLC subsystem, which consists of two electric circuit meshes, RC and RLC, with linear elements; • External interface subsystem, which allows the use of additional external devices when desired for the realization of educational practices; • Servo subsystem, which allows the control of external radiocontrol servomotors by means of a digital output pin of the microcontroller through which a PWM signal can be generated; • Potentiometer subsystem, which consists of a linear potentiometer that allows the user to establish the value of a resistor and, through it, that of a voltage divider, thus generating an analog voltage signal between 0v and 5v that is connected to an analog input pin; • Button subsystem, which includes 3 buttons that the user can use to enter digital data or information and that are connected to three digital inputs of the microcontroller; • SRAM subsystem, responsible for storing data from other subsystems, expanding the storage capacity in static RAM of the microcontroller; Y • Miscellaneous subsystem, which includes components that support other subsystems. 5 10 fifteen twenty 25 30 2. Device according to the previous revindication characterized in that the digital signals received by the digital indicators subsystem are the same as those received by the DAC subsystem and are protected with resistors so that the total current consumption in case all the indicators light up simultaneously be acceptable by the power supply. Device according to any one of claims 1 or 2 characterized in that the analog output of the DAC subsystem is connected to the RC + RLC subsystem, said analogue adjustable signal in order to regulate the outputs of the RC + RLC subsystem, and said subsystem RC + RLC comprising a buffer at the input of the RC mesh that receives said analog output signal from the DAC subsystem and replicates it without changes. 4. Device according to the preceding claim characterized in that the RC + RLC subsystem consists of an RC mesh consisting of a resistor and a capacitor in series, and an RLC mesh consisting of a resistor, an inductance and a capacitor in series, both meshes having unit gain so their outputs can be greater than 5v even if the analog signal of the DAC subsystem is in the range 0-5v. 5. Device according to the previous claim characterized in that the values for the components of the RC mesh are R = 100 ohms and C in the range 2 - 21.7pF; and the values of the RLC mesh components are R in the range 0-500 ohms, L = 47mH and C = 1pF. 6. Device according to the preceding claim characterized in that the RC mesh is manually configurable by means of two switches that allow selecting a capacitor value from a set of 4 different values: 2pF, 6.7pF, 17pF or 21.7pF. 7. Device according to any of claims 5 or 6 characterized in that the resistance of the RLC mesh is variable and configurable by a potentiometer. 8. Device according to any of claims 6 or 7 characterized in that the 5 10 fifteen twenty 25 30 In addition to operating separately, RC and RLC meshes are interconnected so that the RC mesh constitutes a stage prior to the RLC mesh, determining the behavior of the interconnection by regulating the capacitor of the RC mesh. 9. Device according to the previous claim characterized in that by means of the switches that allow to select a value of the capacitor of the RC mesh it is selected that the final output of the RC + RLC subsystem is either that of the RC mesh, or that of the RLC mesh, either that of the buffer at the entrance of the RC mesh without passing through said RC mesh or RLC mesh. 10. Device according to the previous claim characterized in that the final output of the RC + RLC subsystem is protected by two cutting diodes to prevent voltages above 5v or below 0v from reaching the analog input of the microcontroller. 11. Device according to any of the preceding claims characterized in that the external interface subsystem comprises an electrical input and an output interface operating in the voltage range of ± 10v. 12. Device according to the previous claim characterized in that the external interface subsystem transmits, once connected to additional external devices, an analog signal of ± 10v towards them, output signal, and, simultaneously, receives another signal in the same range voltage from them, input signal, said input and output signals not transmitting power. 13. Device according to the preceding claim characterized in that the ± 10v output signal of the external interface subsystem is obtained from the analog output of the DAC subsystem by decoupling said DAC subsystem from the external interface subsystem by passing the output signal of the subsystem DAC first by a buffer and then by an operational amplifier that scales and displaces said signal. 14. Device according to any of claims 12 or 13 characterized in that the 5 10 fifteen twenty 25 30 ± 10v input signal of the external interface subsystem is passed through two operational amplifiers that scale and move it to the range of 0v to 5v, which enters an analog pin of the microcontroller. 15. Device according to the previous claim characterized in that the scaling and displacement of the input and output signals of the external interface subsystem reuse the same reference voltage of 1.25v, whose output limits the output of the DAC subsystem to the range of 0v to 2.5v. 16. Device according to any of claims 14 or 15, characterized in that the voltage conversion associated with the input and output signals of the external interface subsystem requires a power supply of ± 15v, said power supply produced by the miscellaneous subsystem from the power supply 5v of the microcontroller board. 17. Device according to any of the preceding claims characterized in that the servo subsystem receives the PWM signal from the microcontroller, uses it to flash an LED, and, simultaneously, sends it to a series of physical connectors where various types of servo motors can be attached . 18. Device according to the preceding claim characterized in that the series of connectors comprises three different connectors: one for servomotors that use GVS (ground-feed-signal) connectors, another for servomotors that use the VGS connector format, and the last for general loads that receive a power signal commanded by a PWM signal. 19. Device according to the previous claim characterized in that the servo subsystem comprises means for filtering the 5v supply that it sends to the servo in order to prevent the propagation of noise and voltage drops between the servo itself and the electronic educational device. 20. Device according to the preceding claim characterized in that the servo subsystem comprises a resettable fuse in the servo supply path for situations 5 10 fifteen twenty 25 30 exceptional 21. Device according to any of claims 18 to 20 characterized in that the servo subsystem comprises a servo current consumption sensor, located in the power supply path thereof, and implemented by means of a small value shunt resistor plus a voltage amplifier , said sensor providing an analog voltage between 0v and 5v that is proportional to the current that the servo is consuming at all times. 22. Device according to the previous claim characterized in that the data obtained by the servo current consumption sensor is stored using the SRAM subsystem being acquired through an analog input pin of the microcontroller. 23. Device according to any of the preceding claims characterized in that the communications of the SRAM subsystem with the microcontroller can be disabled by means of one of the digital output pins of said microcontroller. 24. Device according to any of the preceding claims characterized in that the Miscellaneous subsystem includes: • A filtering circuit that avoids noise and voltage drops in the supply of the electronic educational device, the output of said circuit being the 5v (and the earth) that feed the rest of the subsystems; • A DC / DC converter that transforms the 5v of the previous filtering circuit into a supply of ± 15v, necessary for the external interface subsystem; • A replica of the names of the pins that the microcontroller provides to the educational electronic device; Y • An electrical bridge that connects, conveniently protected (with a resistor), the digital output pin of the microcontroller that provides the PWM output signal for the servomotor subsystem, and a pin that receives one of the external interruptions of the microcontroller. 25. Device according to the preceding claim characterized in that the subsystem 33 Miscellaneous also includes a resettable fuse for exceptional power consumption situations, and a power indicator LED. 26. Device according to any of the preceding claims characterized in that the miscellaneous subsystem further comprises a button that activates the RESET signal of the microcontroller