RU2391677C1 - Microcontroller metering transducer of capacitance and resistance into binary code - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: metering transducer of capacitance and resistance into binary code comprises microcontroller, reference resistor, capacitance sensor, capacitor of reference capacitance and resistor of measured resistance. Resistors of reference and measured resistance by the first terminals are connected to the first plates, accordingly, of capacitance sensor and capacitor of reference capacitance. Additionally resistive divider of voltage is added into metering transducer. The first terminals of voltage divider resistors are connected to the first input of analogue comparator of microcontroller, and the second ones - to terminals of microcontroller supply.

EFFECT: higher accuracy of measurement.

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Description

FIELD OF THE INVENTION

The invention relates to measuring equipment, in particular to devices for measuring capacitance and active resistance, and can be used in means for measuring and monitoring non-electrical quantities by capacitive and resistive sensors.

State of the art

A device for measuring electrical capacitance is known, comprising two single-vibrators connected according to a circular oscillator circuit, two integrating RC links connected to the outputs of the corresponding single vibrators, an indication unit connected between the outputs of the integrating RC links, capacitors, respectively, of the exemplary one, are included in the timing chains of the single vibrators capacity and measurable. A constant voltage is formed at the output of the device, the value of which depends on the change in the measured capacitance and which is reflected by the display unit (see Pat. RF No. 2156472, class G01R 27/26, published on September 20, 2000).

A disadvantage of the known solution is the limitation of functionality, since the device does not allow to convert the capacity to binary code.

A device for measuring non-electric quantities by capacitor sensors is known, comprising first and second generators, a microcontroller (MK) and a digital indicator, respectively, a capacitor sensor of a measured capacitance and a capacitor of an exemplary capacitance, timing resistors are included in known circuits, with outputs the generators are connected to the counting inputs corresponding to the counters of the MK, one of the conclusions of the MK is connected to the inputs of the resolution of the generation of both generators, digital locator connected to the MC (see. US Pat. Russian Federation №2214610, cl. G01R 27/26, published on 20.10.2003, the).

A disadvantage of the known solution is the relatively high error introduced by generators, the parameters of which depend on external factors.

The closest in technical essence to the claimed technical solution and adopted by the authors for the prototype is a device for measuring the capacitance and dielectric loss of a capacitor sensor, containing MK, a digital indicator, first and second generators, timing circuits, which contain, respectively, a capacitor sensor, a model capacitor capacitances and timing resistors, controlled keys, the outputs of the first and second generators connected to the inputs of the MK, the output of the MK connected to the inputs of the generation permit both generators to the output of the transmission binary code MC connected digital display (see. US Pat. Russian Federation №2258232, cl. G01R 27/26, published on 10.08.2005, the).

A disadvantage of the known solution is the low accuracy of the conversion, due to the error introduced by the generators, the parameters of the output signals of which depend on external factors, for example, temperature.

Disclosure of invention

The technical result of the invention is to improve the accuracy of measurement.

The technical result is achieved by the fact that in a microcontroller measuring capacitance and resistance in a binary code containing MK, microprocessor device, capacitive sensor, a capacitor of exemplary capacity, an exemplary resistor and a resistor of the measured resistance, the output of the binary code, and the resistors of the model and measured resistance by the first conclusions connected to the first plates, respectively, of a capacitive sensor and a capacitor of exemplary capacity, according to the invention in microcontrollers a capacitive measuring transducer introduced a resistive voltage divider, the first terminals of the voltage divider resistors connected to the first input of the MK analog comparator, and the second terminals connected respectively to the MK power terminals, the first terminals of the reference and measured resistors connected to the second input of the MK analog comparator, the second terminals of the reference and the measured resistors are connected respectively to the first and second outputs of the MK, the second plates of the capacitive sensor and the capacitor of the exemplary capacity By connecting respectively to third and fourth outputs MC.

The drawing shows a structural diagram of a microcontroller measuring transducer of capacitance and resistance to binary code.

The implementation of the invention

The microcontroller measuring converter of capacitance and resistance to binary code contains (Fig. 1) a microcontroller 1, an exemplary resistor 2, a capacitive sensor 3, a measured resistor 4, a capacitor of an exemplary capacitance 5, a resistive divider consisting of resistors 6 and 7, an output 8 for transmitting a binary code . Resistors 2 and 4, the first conclusions are connected to the non-inverting input of the analog comparator MK and the first plates of the capacitive sensor 3 and the capacitor 5 of standard capacity, the first conclusions of the resistors 6 and 7 of the voltage divider are connected to the inverting input of the analog comparator MK, and the second conclusions are connected, respectively, to the conclusions MK power supply, the second terminals of resistors 2 and 4 are connected respectively to the first and second MK outputs, the second plates of the capacitive sensor 3 and the reference capacitor 5 are connected respectively to the emu and fourth outputs of MC, data output 8 is connected to the microprocessor MC apparatus to display the measurement result (not shown).

The microcontroller measuring converter of capacitance and resistance to binary code operates as follows.

A voltage equal to 0.63U _p is supplied to the inverting input of the analog comparator MK from a resistive divider 6, 7. To measure the capacitance 3 MK switches off the circuit, consisting of a resistor 4 and a capacitor 5, by translating the second and fourth outputs to which this circuit is connected in a high-resistance state. Then MK outputs a low voltage level (log.0) to the third output and discharges the capacitance 3 through a resistor 2 by outputting log.0 to the first output. After a while, MK 1 outputs a high voltage level (log. 1) to the first output and starts the internal binary counter reset to zero. When the voltage on the capacitive level sensor 3 reaches 0,63U _claim analog comparator output is logic 1 is formed. On this signal MK 1 stops the binary counter and saves its contents, i.e. the binary code N, which is proportional to the time constant τ = Ro · C _x , is determined by the expression N = τ / T, where T is the period (cycle time) of the MK clock, T = 1 / f, where f is the frequency of the MK clock. MK determines the time constant from the expression τ = T · N, and then determines C _x = T · N / R ₀ , where R _{0 is} known.

To measure the resistance of the resistor 4 MK 1 performs the same algorithm as for measuring the capacitance 3. R _x is determined from the expression R _x = T · N / C ₀ , where C _{0 is} known.

Binary codes of the conversion results MK 1 transmits via the output 8 of the binary code transmission to the microprocessor device.

The present invention in comparison with the prototype and other known solutions has the following advantage: reduced measurement errors introduced by the prototype with additional converting devices - generators, thereby increasing the measurement accuracy.

Claims (1)

The microcontroller measuring transducer of capacitance and resistance to binary code contains a microcontroller, a capacitive sensor, a capacitor of exemplary capacitance, a model resistor and a resistor of measured resistance, a binary code transmission output, and the resistors of exemplary and measured resistance are connected to the first plates of the capacitive sensor and the capacitor of exemplary capacity characterized in that a resistive divider is introduced into the microcontroller measuring transducer of the capacitance voltage drop, the first terminals of the voltage divider resistors connected to the first input of the analog comparator of the microcontroller, and the second terminals connected respectively to the power terminals of the microcontroller, the first terminals of the model and measured resistors connected respectively to the first and second outputs of the microcontroller, the second plates of the capacitive sensor and capacitor of the standard capacity connected respectively to the third and fourth outputs of the microcontroller.