ES1077336U - System of assembly and measurement of electronic circuits (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

Assembly and measurement system of electronic circuits on a platform connected to a computer and powered by a feeder connected to the electricity network, said system is characterized in that said platform comprises: - a power module, with two switched sources and a plurality of linear regulators, connected to the feeder; - a microcontroller, with analog input channels and an analog output channel, with connection to the computer and the power module; - a memory connected to the microcontroller; - a user module with connections to an insert plate, to the analog input channels of the microcontroller, to the analog output channel of the microcontroller and to the power supply module; - a signal generating module connected to the user module and also connected to the insert plate; - a signal capture module connected to the user module and also connected to the insert plate. (Machine-translation by Google Translate, not legally binding)

Description

Assembly and measurement system of electronic circuits.

Object of the invention

The present invention has application in the technical sector of circuit electronics, such as electronic circuits that are mounted in teaching laboratories for the study of different devices and assemblies, and refers to a system for the assembly and measurement of said circuits

More specifically, the object of the invention is a hardware platform that, connected to a PC, allows to have at a low cost functionalities typical of a traditional electronics laboratory, such as assembly, testing,

10 measurement or signal acquisition procedures

Background of the invention

The study of electronic technology has traditionally always been linked to the use of face-to-face laboratories where a teacher guides students in the use of different devices, assemblies and measuring instruments to acquire knowledge and professional skills. In the last decades it

15 have produced technological advances that have allowed significant changes in the teaching-learning pedagogical models, opening the door to virtual (or distance) teaching of technological competences, including those in the field of electronics. Currently, both in face-to-face and virtual models, the student has become the fundamental axis of the teaching-learning process and it is essential to provide new tools for the acquisition of these skills.

20 The cost of laboratories has traditionally been high and this usually leads to a restrictive use of electronic measuring instruments and assemblies by students. With the aim of reducing the costs of implementing hardware laboratories, solutions with different approaches have appeared in recent years, in order to reduce the costs of developing practice environments in educational institutions. These lines of research have basically focused on two different areas: the in situ approach, which aims to

25 develop affordable electronic equipment to reduce implementation costs; and the remote approach, which allows remote access to measuring equipment and improves the efficiency of their use, facilitating access to a much higher number of students and in a wider schedule.

The solutions of the National Instruments company, especially with two proprietary equipment such as MyDAQ and ELVIS, are noteworthy in the variety of on-site solutions that have appeared in recent years.

30 These two academic solutions allow the development of physical laboratories for educational purposes at a reasonable cost, thanks to the integration of lower performance instruments than those used in the professional field.

MyDAQ is a portable device designed by the National Instruments company for educational purposes, which, fundamentally, provides a whole set of measuring devices in order to analyze electronic circuits outside the classroom and in the laboratory. The device consists of 2 analog inputs, 2 analog outputs, 8 configurable digital inputs, audio input / output, power supply outputs at ± 15V and + 5V. It offers the possibility of measuring voltages, currents and resistances. The device has a size that allows you to easily carry it in a backpack or in a large pocket and allows you to make measurements by using the licenses of LabView, proprietary software of National Instruments that requires the payment of

40 licenses The purpose of this device is to take the laboratory to any place and at any time whenever a PC and a license for its use are available. It has the disadvantage of not allocating hardware support for circuit assembly.

ELVIS is a device also developed by the National Instruments company that forms a much more complete plate than MyDAQ and allows mounting on an insert plate (or 45 protoboard). This device makes available to users a series of physical and virtual instruments, a data acquisition device via a high-speed USB bus and a workstation with a prototype development card, which makes it one of the most complete and versatile tools on the market. The use of this tool allows the design and analysis of circuits for learning analog and digital electronics, data acquisition and signal conditioning among other things. This

50 equipped with a set of virtual instrumentation and proprietary control software from National Instruments. The cost of this device is very high so it can hardly be acquired by a student individually, so that its academic use is oriented to the implementation of the face-to-face laboratory in the educational centers or by installing it in a remote laboratory, of such that the student remotely control the PC that governs it.

55 Other types of devices in the line of the above and reduced cost are USB instrumentation devices. These types of devices are essentially digital oscilloscopes with some extended signal generation function. These devices are low cost, but have much more limited functionality than those presented above. They allow to capture signals and perform simple analyzes and visualize them with the PC. The cost of these devices depends, fundamentally, on their performance, but it is not usually a

60 problem, because it is not usually excessively high. These devices have the main drawback that they do not allow mounting directly, as they require external platforms that allow mounting, which complicates the use in teaching applications by requiring additional hardware. However, these solutions can be a good alternative to have a portable measuring device that can be used on a PC.

The state of the art therefore presents some alternatives to the classic electronic laboratories, but these solutions do not optimally cover the functionalities of a laboratory without triggering the required portability or cost conditions. In this context, the problems derived from the cost of complete equipment make it difficult for students to access equipment that, without resorting to external elements, allows the full functionality of an electronics laboratory to be developed.

Description of the invention

The present invention relates to an electronic circuit assembly and measurement system that overcomes the drawbacks described above, as it brings together the elements to develop the processes and functionalities of a traditional electronic laboratory in a single platform of reduced cost and good conditions of portability.

Specifically, the electronic circuit assembly and measurement system proposed by the invention comprises a platform connected to a computer and powered by a feeder connected to the power grid; furthermore it comprises a power module, with two switched sources and a plurality of linear regulators, connected to the feeder; a microcontroller, with two analog input channels and an analog output channel, with connection to the computer and the power module; a memory connected to the microcontroller; a signal generation module connected to the analog output channel of the microcontroller and the user module; a signal capture module connected to the two analog input channels of the microcontroller and the user module; a user module with an insert plate that allows the user to mount electronic circuits and with connections to the signal capture module, the signal generation module and the power module.

The invention contemplates in its preferred embodiment that the signal generation module comprises an operational amplifier, a variable gain amplifier, a class AB power stage and a short-circuit protection element. In this way a periodic function generator is implemented.

It is also contemplated that the signal capture module comprises a buffer, a variable gain amplifier and an operational amplifier. In this way an oscilloscope is implemented.

The signal capture module can implement a voltmeter in one of the embodiments.

The combination of the signal capture module and the signal generation module can be used, in one of the embodiments to implement an ammeter or an ohmmeter.

The memory of the microcontroller can be of the EEPROM type and the connection of the microcontroller with the PC can be made through a USB or miniUSB connection.

As for the switched sources of the power module, it is contemplated that a source is of the “step-down” type or voltage drop converter, to reduce the voltage with which the system is fed from the power supply, and another source of type "inverting converter" or inverter converter to obtain negative voltages. Using said switched sources together with the effect of the linear regulators, the power module can offer a plurality of voltages of values + 15V, -15V, -5V, + 5V and 12V.

As for the user module, it can include a switch that enables or disables electronic circuits mounted on the insert plate, allowing areas of said electronic circuits to be isolated without disconnecting them. The user module can also include a push button and a multiturn potentiometer, which can also be integrated into the electronic circuits mounted on the insert plate.

A final aspect of the invention reflects the possibility of connecting a plurality of LED status indicators to the microcontroller to encode different states of the system.

Thus, in accordance with the described invention, the system proposed by the invention constitutes an advance in the assembly and measurement systems of electronic circuits, mainly in the academic field, since it satisfactorily solves the problem presented regarding the obligation to combine external elements for the measures or other functions, the high price of the most complete equipment that makes its use impossible, the restrictions posed by the mandatory proprietary software or the difficulties of carrying the equipment.

Description of the drawings

To complement the description that is being made and in order to help a better understanding of the characteristics of the invention, according to a preferred example of practical implementation thereof, a set of drawings is attached as an integral part of said description. In an illustrative and non-limiting manner, the following has been represented:

Figure 1.- Shows a schematic view of the complete system. Figure 2.- Shows a block diagram of the system power module. Figure 3.- Shows a block diagram of the function generator that includes the system. Figure 4.- Shows a block diagram of the oscilloscope that includes the system. Figure 5.- Shows a general diagram of a pre climber.

Preferred Embodiment of the Invention

In view of the aforementioned figures, it can be observed that in one of the possible embodiments of the invention, the measurement and assembly system has an electronic plate of dimensions, for example 167 * 182 * 20 mm where the following elements represented are preferably incorporated in figure 1:

-

A power module 2 with the circuitry necessary to generate all the voltages that feed the rest of the board, as well as to be used in the user module which, in the case of the preferred embodiment are of value + 15V, -15V, + 5V, -5V and 12V. Users have access to these voltages preferably through connectors installed in the user module. This power module consists of several stages constructed by means of two switched sources (preferably one configured as a voltage drop converter 21 is used, to obtain the 3.3 V from the 24 V to which the board is fed; and another configured as an inverter converter 22, in order to obtain the negative voltages) and various linear regulators (23, 24, 25, 26, 27, 28, 29, 20), along which all the necessary voltages are obtained. The distribution of these stages is shown in Figure 2, in the form of a block diagram.

Both the switched sources and the linear regulators of this preferred embodiment can withstand high currents, for example between 1A and 100 mA. However, as there are no heatsinks in the integral devices, the maximum output current that each source can deliver is reduced. For a safe use, a maximum current of 10 mA has been defined for each power source, the five sources being working simultaneously (if only one is working, this current can reach 50 mA).

-

A microcontroller 3 used to govern the system connected to a computer and the power module, which, in the case of the preferred embodiment, uses the STM32F107VC of the house ST Microelectronics. It contains an ARM Cortex M3 72 MHz core and is accompanied by a small EEPROM memory (model M24512, also from the ST Microelectronics house), which allows you to store data and also allows you to update the firmware from a PC computer, preferably through a USB or miniUSB connection. The capacity of this memory is 512 Kbytes and can communicate via I2C communication lines with the microcontroller. The functions performed by the microcontroller, essentially, to generate and capture the signals that are delivered and received, respectively, in the user module (through two analog input channels and one analog output); configure system parameters; and manage the entire communication process with the PC through the USB port.

The hardware directly associated with the microcontroller consists of a quartz crystal, for example 25 MHz, necessary to generate the microcontroller's clock signal; a JTAG connector (Joint Test Action Group, IEEE 1149.1-1990 standard) to implement programming and debugging tasks; and a whole set of decoupling capacitors, necessary to reduce switching noise levels.

The hardware associated with EEPROM memory consists only of two polarization resistors to raise the voltage of the I2C communication lines, which are directly connected to the microcontroller.

-

A user module 5 connected to the microcontroller (by its two analog input channels and the analog output channel), the power module and with an insert plate, preferably protoboard, in which the user can make all the assemblies that You want your circuits and the connections of both the power supplies and the measurement and signal generation devices with which you work from the PC comfortably. To make these connections, cable, preferably 0.28 mm single-wire cable, is introduced into the desired holes and applying some pressure on both the protoboard and the connectors.

Apart from the protoboard insertion plate on which to make the assemblies and the connectors corresponding to the devices and sources, the system also includes the possibility of integrating other components with variable behavior into the user module. For example, a switch is useful. The signal generation and capture module also includes two pre-climbers and a post-scaler that contain all the necessary circuitry to ensure that the analog signals that are delivered (from the PC and through the microcontroller) to the module of user 5 and also those received from it (back to the PC, after passing through the microcontroller), move in the range of amplitude that is required in each case (depending on, for example, the voltage of peak to

to isolate parts of a circuit without disconnecting them, a button, for example, the

study of circuits with transient behaviors, or a multiturn potentiometer, preferably

of 10 KΩ, for being a manually variable resistance of great utility for, for example, modifying the

gain in amplifier circuits or adjust the cutoff frequencies in the filters.

5

-

A signal generation and capture module 8 with two distinct parts:

o A periodic function generator 4 implemented from the module for generating

signal, connected to the user module and also to the insert plate, which allows

deliver in the user module a voltage signal through the analog output channel

of the microcontroller, after passing through a stage of the post climber 1. It is required for this

generate the samples corresponding to the basic period of the desired signal from the PC, the

time between samples desired and the level of the post climber 1.

fifteen

The function generator function in this preferred embodiment of the invention

is that the microcontroller has a digital – analog converter 31 that can generate

voltages between 0 and 3.3 V. In order to have negative voltages, the output signal of the

Converter goes through an operational amplifier 32 that adds a negative offset. So, in the

Outputs of the operational voltages are obtained between -1.65 and +1.65 V. Next, a

variable gain amplifier 33 (or post climber) that allows to obtain voltages of

15V peak output both positive and negative. The final part of the generator, consists of

a small class AB 34 power stage, which provides the required current (with a

50 mA maximum). As a protection measure, a generator is included in the output of the generator

resistance of positive temperature coefficient (or polyswitch) 35 of 50 mA to limit

25

possible short circuits or possible excess consumption. An outline can be seen in the figure

3.

o An oscilloscope 5 implemented from the signal capture module, connected to the module

of user and connected to the insert plate that allows to capture two voltage signals at

through the two analog input channels of the microcontroller, after passing through the

Pre climbers stages. It is necessary to set the capture rate of the signals from

input (sampling frequency of the analog-digital converters that has the

microcontroller), the levels of the pre-climbers to adjust the signal voltages

to the volts per division selected in the oscilloscope) and the trigger conditions (level,

35

channel and type of trigger, which determine the moment at which the measurement starts) of the process of

signal capture

The oscilloscope consists of three blocks. For each of its two capture channels (41.42),

first a buffer (43,44) appears that guarantees a very high input impedance

high, in order to avoid falls due to mismatch of impedance of the input voltage.

Next, there is the pre climber (45.46) of the channel, whose gain is set to

function of the signal level present in the input so as not to saturate it. Since the channels of

Microcontroller input do not accept voltages higher than 3.3V, the pre climber

it must be adjusted under the premise that there is no more than 3.3 V peak to peak at its output. How

Four. Five

protection measure, a resistance coefficient of

positive temperature (or polyswitch) 35 of 50 mA to limit possible short circuits or a

Possible excess consumption. And lastly, there is another operational amplifier

(49.50) which adds an offset to the signal in order to guarantee a signal between 0 and 3.3 V in the

microcontroller input It can be represented in the block diagram of the figure

Four.

The equivalence, in this preferred embodiment, between the level of tension captured by the

oscilloscope and the signal received in the analog-digital converter of the microcontroller is the

next:

55

Voltage in the User Zone

Voltage in the A / D converter

-15 V

0V

0V

+ 1.65 V

+15 V

+3.3 V

5 peak selected in a generator of periodic functions, of the selected full scale scale in a multimeter or of the volts per division selected in an oscilloscope - the interfaces of all these devices would be implemented by software from the PC -).

On the one hand, the pre-climbers (there are two, one for each input channel of the oscilloscope) are located between the output signal jacks of the user module 5 and the inputs of the A / D converters integrated in the microcontroller, and are necessary to be able to implement oscilloscopes or other measuring devices (such as, for example, a voltmeter or a multimeter) that need to capture analog signals from the user module 5.

On the other hand, the post climber (there is one, corresponding to the output channel of the signal generation module) is located between the output of the D / A converter integrated in the microcontroller and the input signal socket of the user module, and it is necessary to be able to implement periodic function generators or other devices (such as, for example, an ohmmeter or a modulated signal generator) that need to deliver analog signals in the user module.

The respective circuitry of the pre-climbers and the post-climber are based on two parts. The first consists of an operational amplifier 51 that amplifies the signal as a function of the second part, the variable resistance. This variable resistor consists of two 52.53 analogue switches with four positions each (governed by the microcontroller) with which different resistance values can be selected (54-61). This selection is what allows the output voltage level to be generated, depending on the voltage scale background on which you want to work. Figure 5 illustrates a general diagram of a pre climber (the case of the post climber is directly analogous).

-

A USB 6 connection to make the connection for the computer, preferably USB 2.0, which guarantees the necessary speeds and is the most widespread host-peripheral communication standard.

At the hardware level, since the microcontroller already provides almost everything necessary to implement this connection, only a mini USB connector and an integrated one are mounted to protect the microcontroller against possible electrostatic discharge.

-

A set of status indicators 7, preferably LED diodes, which in the preferred embodiment are a set of 3 red, green and yellow LED diodes, all connected to the microcontroller. The system uses these diodes to transmit to the user certain information that it encodes through a color code. The different states that are contemplated in the preferred embodiment are:

o The USB is not detected or the connection to the computer cannot be established. The microcontroller does not start. (three LEDs off).

o The platform is ready to be used. There is a USB connection to the computer (the first LED off, the second yellow, the third green).

o Firmware is being loaded into EEPROM memory (the first red LED and blinking, the second yellow, the third green).

o A checksum (or checksum) of the EEPROM memory is being made (the first red LED, the second yellow, the third green).

o The microcontroller memory is being programmed (the first LED off, the second green and flashing, the third off)

A fourth LED may be optionally included, for example a red LED on the opposite side of the insert plate, to indicate the presence (on) or absence (off) of power.

Other measuring devices outside the function generator and the oscilloscope, which have been implemented in this preferred embodiment, are contemplated in other embodiments of the invention. A voltmeter, a frequency meter or a peak detector can be implemented by developing small software changes in the computer connected to the system. It also contemplates the possibility of implementing other measuring devices with different functionalities, such as an ammeter or an ohmmeter, adding only one or two necessary components in the protoboard insert plate.

The present invention uses a computer as an interface with the user. Some software functions have been developed that facilitate user control of the system. Many modifications can easily be made to adapt the functionality of the system, but only the operation of the signal generation and signal capture modules for their preferred implementation, which is the generation of periodic functions and an oscilloscope respectively, is detailed below.

The signal generation module can be controlled from the computer thanks to tools that allow you to send the necessary samples and configure the parameters mentioned above.

That is, the user can enter, through the computer, the capture speed of the input signals (sampling frequency of the analog-digital converters that the microcontroller has), the levels of the pre-scalers to adjust the voltages of the signals to the volts per division selected in the oscilloscope) and the trigger conditions (level, channel and type of trip, which determine the moment at which the measurement starts) of the signal capture process.

The function that adjusts the sample time (or sampling frequency) of the signal to be generated includes the configuration of two parameters, PSC (the pre-scaler of the internal timer of the microcontroller) and ARR (the self-start record of the internal timer of the microcontroller), whose values must necessarily be integers between 0 and 255 and that allow to determine the time between samples (the fundamental frequency of the generated analog signal will always depend on the sampling frequency and the number of samples of the basic period of said signal).

The relationship between the sample time (Ts) and the PSC and ARR parameters is detailed below:

(PSC +1) · (ARR +1) Ts = 72 MHz

where the 72 MHz corresponds to the frequency of the internal clock of the microcontroller. Thus, for example, to generate a periodic signal of 100 Hz of fundamental frequency (f)

to

from a basic period of 512 samples the first thing is to calculate the time between samples (Ts):

Ta11 11

Ts = = · = · = 19.53 / sec

number of samples number of samples 100 512

to

Now you can apply the first equation:

(PSC +1) · (ARR +1) Ts = 72 MHz

Ts72 MHz

ARR = −1

PSC +1

In this calculation a degree of freedom appears: the value of the PSC parameter. By setting it, for example, to 20, the corresponding value of the ARR parameter is obtained:

19.53 · 10-6 · 72 · 106

ARR = −1 = 65.96≅66

20 +1

The only limitation when determining the values of the PSC and ARR parameters is that they must meet the following inequality:

72 MHz

<351 kHz

(PSC + 1) · (ARR +1)

where the 351 kHz corresponds to the maximum sampling frequency at which the board can work. Thus, from the computer software this calculation can be optimized to obtain the two integer values for the PSC and ARR parameters that, respecting this inequality, better approximate the value of Ts.

As for the signal capture module and in order to be able to capture the samples and configure the parameters, the user can use the computer to configure the capture speed of the input signals (frequency) through a set of functions implemented in software of sampling of the analog-digital converters that the microcontroller has), the levels of the pre-scalers to adjust the voltages of the signals to the volts per division selected in the oscilloscope) and the trigger conditions (level, channel and type of shot , which determine the moment at which the measurement starts) of the signal capture process.

The function that allows setting the sample time (or sampling frequency) of the A / D converters of the microcontroller is analogous to that used for the signal generation module. The calculation conditions of the PSC and ARR parameters are identical to those present in the case of the signal generation module, with the only difference that the sampling frequency of the A / D converters is now set instead of the time between samples generated by the D / A converter. Knowing that the maximum sampling frequency at which the board can work is 351 kHz, if, by way of example, you want to guarantee a minimum of 10 samples per period, the maximum analog frequency that should be handled from the user module It would be 35.1 kHz.

5 The trigger conditions of the signal capture process are set by a function with several parameters. A first parameter indicates on which input channel the trip is applied, a second parameter indicates the type of trip, which can be set for a trip by rising edge or for a shot by falling edge, and a third parameter indicating the level pre-shot (between 0 and

10 100%)

Finally, a fourth parameter encodes the trigger level (adopting values between 0 and 4095 resulting from coding the standardized trigger voltage level in a 12-bit word). To calculate this code, both the selected pre-climber level and the

15 offset of +1.65 V that is added to the signal before attacking the A / D converters of the microcontroller. Thus, if, for example, it is desired to set a trigger level of 2.5 V with a pre-climber set at 0.556 (200 mV / div, see Table 3), the value of this fourth parameter is calculated as follows:

(0.556 2.5V) +1.65V

Trip = 4095 = 3772.36 ≅ 3772

3.3V

Claims (12)

1.-System for mounting and measuring electronic circuits on a platform connected to a computer and powered by a feeder connected to the power grid, said system is characterized in that said platform comprises:

-

a power module, with two switched sources and a plurality of linear regulators, connected to the feeder; -a microcontroller, with analog input channels and an analog output channel,

with connection to the computer and the power module; -a memory connected to the microcontroller; -a user module with connections to an insert plate, to the input channels analog of the microcontroller, to the analog output channel of the microcontroller and to the power module; -a signal generation module connected to the user module and also connected to the insertion board; -a signal capture module connected to the user module and also connected to the insert plate. 2. The system of the preceding claim wherein the signal generation module comprises an operational amplifier, a variable gain amplifier, a class AB power stage and a short-circuit protection element that implements a periodic function generator. 3. The system of any of the preceding claims wherein the signal capture module comprises a buffer, a variable gain amplifier and an operational amplifier that implements an oscilloscope. 4. The system of any of the preceding claims wherein the memory connected to the microcontroller is an EEPROM type memory. 5. The system of any of the preceding claims wherein the connection of the microcontroller with the computer is of the USB type or of the miniUSB type. 6. The system of any of the preceding claims wherein one of the two switched sources of the power module is a voltage drop converter and the other is an inverter converter. 7. The system of claim 6 wherein the power module further comprises a plurality of voltage sockets of values + 15V, -15V, + 5V, -5V and 12V. 8. The system of any of the preceding claims wherein the user module further comprises a switch that enables or disables the electronic circuit mounted on the insert plate. 9. The system of any of the preceding claims wherein the user module further comprises a multiturn potentiometer. 10.-The system of any of the preceding claims wherein the user module further comprises a button. 11. The system of any of the preceding claims which further comprises a plurality of LED diodes, connected to the microcontroller, indicators of different states of the system. 12. The system of any of the preceding claims wherein the insert plate further comprises an electronic circuit mounted by a user.