RU162372U1 - MICROCONTROLLER ADC USING THE TRANSITION PROCESS IN THE RC CIRCUIT - Google Patents

Abstract

A microcontroller ADC using a transient process in an RC circuit, containing a microcontroller with an integrated analog comparator, a capacitor, four resistors (the resistances of the second and third resistors are equal): the first resistor and capacitor are connected to the first input of the analog comparator built into the microcontroller; the first conclusions of the second and third resistors are connected to the second input of an analog comparator built into the microcontroller; the second conclusions of the first, second, third resistors and capacitor are connected respectively to the first, second, third and fourth discrete outputs of the microcontroller; the second terminal of the fourth resistor is connected to the second terminal of the third resistor, characterized in that a negative voltage sign detection and inversion unit (BOS and ION) is introduced into the device, containing an analog inverter, a comparator, a first (normally closed) analog key, and a second (normally open) analog key: the BOS and ION input is connected simultaneously to the first (non-inverting) input of the comparator, to the signal input of the second (normally open) analog key and, through the analog inverter, to the signal ode first (normally closed), the analog switch; the second (inverting) input of the comparator is “grounded”; the output of the comparator is simultaneously connected to the second output of the BOS and ION and the control inputs of analog keys, the outputs of which are connected to the first output of the BOS and ION, the input of the BOS and ION serving as the input of the device, the first output of the BOS and ION connected to the first output of the fourth resistor, the second output of the BOS and ION is connected to a microcontrol discrete input

Description

The technical field to which the utility model relates.

The utility model relates to measuring equipment, in particular to analog-to-digital converters, and can be used in digital systems for measuring and monitoring analog quantities.

State of the art

Known is a composite high-speed analog-to-digital converter containing an m-bit parallel analog-to-digital converter of a rough scale, an n-bit parallel analog-to-digital converter, a difference amplifier, three sampling and storage circuits, three memory registers, a digital-to-analog converter, a unit for determining the sign and inverting negative voltage , synchronization unit ([1]. Patent RU 2311731, IPC Н03М 1/38).

The disadvantage of this device is the high degree of complexity of implementation.

There are also a number of technical solutions related to analog-to-digital converters:

[2]. Patent RU 58823, IPC Н03М 1/26;

[3]. Patent RU 58824, IPC Н03М 1/26;

[four]. Patent RU 58825, IPC Н03М 1/34;

[5]. Patent RU 58826, IPC Н03М 1/38;

[6]. Patent RU 59915, IPC Н03М 1/60;

[7]. Patent RU 61968, IPC Н03М 1/34;

[8]. Patent RU 63625, IPC Н03М 1/26;

[9]. Patent RU 63626, IPC Н03М 1/34.

The disadvantage of devices is the high degree of complexity of implementation.

The closest analogue is the prototype of the claimed technical solution is a microcontroller ADC using a transient in an RC circuit ([10]. Patent RU 2523208, IPC Н03М 1/38).

A microcontroller ADC using a transient process in an RC circuit contains a microcontroller, a capacitor, four resistors (the first three resistors are exemplary, the resistances of the second and third resistors are equal), and the first resistor and capacitor are connected to the first input of the analog comparator (AK) built into microcontroller; the first conclusions of the second and third resistors are connected to the second input of the AK built into the microcontroller; the second conclusions of the first, second, third resistors and capacitor are connected respectively to the first, second, third and fourth discrete outputs of the microcontroller; the first terminal of the fourth resistor is connected to an input voltage source; the second terminal of the fourth resistor is connected to the second terminal of the third resistor.

The disadvantage of this device is its limited functionality - the device can be used to measure and control only unipolar analog signals (signals of positive polarity).

Utility Model Disclosure

The technical result that can be achieved using the proposed utility model is to expand the functionality - the device can be used to measure and control both unipolar and bipolar analog signals.

The technical result is achieved by the fact that in the microcontroller ADC using a transient in an RC circuit containing a microcontroller, a capacitor, four resistors (resistances of the second and

of the third resistors are equal): the first resistor and capacitor with the first conclusions are connected to the first input of the analog comparator (AK) built into the microcontroller; the first conclusions of the second and third resistors are connected to the second input of the AK built into the microcontroller; the second conclusions of the first, second, third resistors and capacitor are connected respectively to the first, second, third and fourth discrete outputs of the microcontroller; the second output of the fourth resistor is connected to the second output of the third resistor, a unit for determining the sign and inverting negative voltages (BOS and ION) is introduced, the input of the BOS and ION serving as the input of the device, the first output of the BOS and ION connected to the first output of the fourth resistor, the second output of the BOS and ION is connected to the discrete input of the microcontroller.

BOS and ION contains an analog inverter, a comparator, a first (normally closed) analog key, a second (normally open) analog key; the BOS input and the ION are connected simultaneously to the first (non-inverting) input of the comparator, to the signal input of the second (normally open) analog key and, through the analog inverter, to the signal input of the first (normally closed) analog key; the second (inverting) input of the comparator is “grounded”; the output of the comparator is simultaneously connected to the second output of the BOS and ION and the control inputs of analog keys, the outputs of which are connected to the first output of the BOS and ION.

Brief Description of the Drawings

In FIG. 1, a block diagram of a microcontroller ADC using a transient in an RC circuit is shown.

In FIG. 2, a block diagram of a unit for determining the sign and inverting negative voltages is shown.

In FIG. 3 shows timing diagrams explaining the operation of the device.

Utility Model Implementation

A microcontroller ADC using a transient in an RC circuit contains a first resistor 1, a second resistor 2, a third resistor 3, a fourth resistor 4, a capacitor 5, a microcontroller 6 with an integrated analog comparator, a unit for determining the sign and inverting negative voltages (BOS and ION) 7 moreover, the resistor 1 and the capacitor 5 are connected by the first terminals to the first input of an analog comparator (AK) built into the microcontroller 6; the first conclusions of resistors 2 and 3 are connected to the second input of the AK built into the microcontroller 6; the second conclusions of the resistors 1, 2, 3 and the capacitor 5 are connected respectively to the first, second, third and fourth discrete outputs of the microcontroller 6; the first output of the BOS and ION 7, through a resistor 4, is connected to the second output of the resistor 3 and the third discrete output of the microcontroller 6, the discrete input of which is connected to the second output of the BOS and ION 7, the input of which serves as the input of the device.

BOS and ION 7 contains an analog inverter 8, a comparator 9, a first (normally closed) analog switch 10, a second (normally open) analog switch 11; input BOS and ION 7 is connected simultaneously to the first (non-inverting) input of the comparator 9, to the signal input of the second (normally open) analog key 11 and, through the analog inverter 8, to the signal input of the first (normally closed) analog key 10; the second (inverting) input of the comparator 9 is “grounded”; the output of the comparator 9 is simultaneously connected to the second output of the BOS and ION 7 and the control inputs of analog keys 10 and 11, the outputs of which are connected to the first output of the BOS and ION 7.

The operation of the device is illustrated by timing diagrams (Fig. 3), which show:

- input voltage of the device u _I (Fig. 3A);

- output voltage u _{9 of the} comparator 9 (Fig. 3b);

- the output voltage u _{11 of the} analog switch 11 (Fig. 3B);

- output voltage u _{8 of the} analog inverter 8 (Fig. 3d);

- output voltage u _{10 of the} analog switch 10 (Fig. 3d);

- output voltage u _out1 BOS and ION 7 (first output) (Fig. 3E);

- output voltage u _out2 BOS and ION 7 (second output) (Fig. 3g).

A microcontroller ADC using a transient process in an RC circuit operates as follows.

BOS and ION 7 is designed to determine the sign (polarity) of the voltage level of the input signal and relay the signal further with a unit transmission coefficient, and in the case of negative polarity, expose the translated inversion signal.

In the case of a BOS and ION 7 (device) input having a positive polarity signal (time intervals [t ₁ ; t ₂ ], [t ₃ ; t ₃ ], (Fig. 3)):

- the comparator 9 generates a signal with the level of a logical unit (Fig. 3b);

- at the second output of the BOS and ION 7, a signal is formed with the level of a logical unit;

- (normally open) analog switch 11 is put into a closed state;

- (normally closed) analog switch 10 is put into an open state;

- the input signal is transmitted, through a closed analog switch 11, to the first output of the BOS and ION 7 (Fig. 3B).

In the case of the input of the BOS and ION 7 (device) signal of negative polarity (time intervals [t ₂ ; t ₃ ], [t ₄ ; t ₅ ], (Fig. 3)):

- the comparator 9 generates a signal with a logic zero level (Fig. 3b);

- at the second output of the BOS and ION 7, a signal is formed with a logic zero level;

- (normally open) analog switch 11 is placed in an open state;

- (normally closed) analog switch 10 is put into a closed state;

- the input signal inverted by means of an analog inverter 8 (Fig. 3d) is transmitted, through a closed analog key 10, to the first output of the BOS and ION 7 (Fig. 3d).

Thus, BOS and ION 7 actually forms the module (1) (Fig. 3e) and the sign (2) (Fig. 3g) of the transmitted signal.

,

- выходное напряжение БОЗ и ИОН 7 на первом и втором выходах (U_вых1, U_вых2 - фиг 2);Where

,

- the output voltage of the BOZ and ION 7 at the first and second outputs (U _o1 , U _oo2 - Fig 2);

U ¹ and U ⁰ - high and low voltage levels - logical unit and zero levels.

Microcontroller 6 operates asynchronously with BOS and ION 7 (comparator 9).

, на выходе АК, встроенного в микроконтроллер 6, поменяется логический уровень. По этому событию микроконтроллер 6 останавливаетMicrocontroller 6 transfers the second and third discrete outputs to a high-resistance state, and displays a low voltage level to the first and fourth discrete outputs. The capacitor 5 is discharged through the resistor 1. To the second input of the AK built into the microcontroller 6, through the resistors 4 and 3 is applied, the voltage from the first output of the BOS and ION 7, which translates the input signal module (Fig. 3e). The voltage from the second output of the BOZ and ION 7, which translates the sign of the input signal (Fig. 3g), is supplied to the digital input of the microcontroller 6. Then the microcontroller 6 outputs a high voltage level, the value of which is U, to the first discrete output and starts a previously reset internal counter. As soon as the voltage U _C on the capacitor 5 is equal to the output voltage

, at the output of the AK built into the microcontroller 6, the logic level will change. The microcontroller 6 stops at this event.

. Микроконтроллер 6 определяет U_C используя выражение (3)an internal counter whose binary code is proportional to the charge time t of the capacitor 5 to the input voltage level, when

. Microcontroller 6 determines U _C using expression (3)

where τ = RC is the time constant of the RC circuit, consisting of resistor 1 and capacitor 5.

есть результат преобразования.In this case

is the result of the conversion.

To improve the accuracy of measurement (conversion), the microcontroller 6 periodically uses a cycle to refine the value of the time constant of the RC circuit. This cycle is as follows.

падает на резисторе 4. Так как сопротивления резисторов 2 и 3 равны, то напряжение, подаваемое на второй вход АК, встроенного в микроконтроллер 6, определяется выражениемThe microcontroller 6 outputs a high voltage level to the second discrete output and a low voltage level to the third discrete output. Input voltage

drops on resistor 4. Since the resistances of resistors 2 and 3 are equal, the voltage supplied to the second input of the AK built into the microcontroller 6 is determined by the expression

The microcontroller 6 determines, using the conversion cycle described above, the time constant of the RC circuit from the expression

Introduction to the composition of the device BOS and ION 7, in analog-to-digital processing of bipolar signals, in contrast to standard schemes for converting a bipolar input signal into a range of one polarity ([11]. Zvonarev E. Drivers for ADCs based on an operational amplifier from Texas Instruments / / Components and technologies. 2007. No. 11, Fig. 3, 4. [Electronic resource] http://kit-e.ru/articles/usil/2007_11_33.php (accessed: October 12, 2015)) leads:

a) to increase the resolution of the ADC by one bit (the highest bit of the code, which carries information about the polarity of the input signal, forms the BOS and

ION 7);

b) the possibility of recalculating the dynamic range of the input signals and the quantization step of the AK built into the microcontroller 6 (doubling them), which contributes to a significant increase in the accuracy of the analog-to-digital conversion of the input signals due to the increased noise immunity of the AK built into the microcontroller 6.

The proposed technical solution, in comparison with the prototype, has advanced functionality.

Claims (1)

A microcontroller ADC using a transient process in an RC circuit, containing a microcontroller with an integrated analog comparator, a capacitor, four resistors (the resistances of the second and third resistors are equal): the first resistor and capacitor are connected to the first input of the analog comparator built into the microcontroller; the first conclusions of the second and third resistors are connected to the second input of an analog comparator built into the microcontroller; the second conclusions of the first, second, third resistors and capacitor are connected respectively to the first, second, third and fourth discrete outputs of the microcontroller; the second terminal of the fourth resistor is connected to the second terminal of the third resistor, characterized in that a negative voltage sign detection and inversion unit (BOS and ION) is introduced into the device, containing an analog inverter, a comparator, a first (normally closed) analog key, and a second (normally open) analog key: the BOS and ION input is connected simultaneously to the first (non-inverting) input of the comparator, to the signal input of the second (normally open) analog key and, through the analog inverter, to the signal ode first (normally closed), the analog switch; the second (inverting) input of the comparator is “grounded”; the output of the comparator is simultaneously connected to the second output of the BOS and ION and the control inputs of analog keys, the outputs of which are connected to the first output of the BOS and ION, the input of the BOS and ION serving as the input of the device, the first output of the BOS and ION connected to the first output of the fourth resistor, the second output of the BOS and the ION is connected to the discrete input of the microcontroller.

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