ZMPT101B

An Arduino library to interact with the ZMPT101B, an active single phase AC voltage sensor module.

This library is based on Ruslan Koptev ACS712 current sensors library for Arduino https://github.com/rkoptev/ACS712-arduino. This library is modified so that it can be used with ZMPT101B voltage sensor with the same code principle. An alternate constructor and method are also included to provide a similar structure to that in the Rob Tillaart library.

Methods

Constructor

ZMPT101B(uint8_t pin, uint16_t frequency = DEFAULT_FREQUENCY);

Basic constructor has a parameters pin for analog input to tell where is connected and the frequency value of the AC voltage that the sensor will measure (by default 50.0Hz).

ZMPT101B (uint8_t pin, float adcVref, uint16_t adcScale, float sensitivity);

Alternate constructor provides a similar structure to that used in the Tillaart ACS712 library. It has parameters pin to identify the ADC to which the sensor is connected, adcVref to identify the ADC reference voltage, adcScale to set the ADC scale and sensitivity to set the sensitivity of the sensor.

Reading RMS Voltage Value

float getRmsVoltage(uint8_t loopCount = 1)

This method allows us to obtain the root mean square (RMS) value of the voltage. By default this method will only calculate the RMS value of one period wave. If you want the calculation to be done over several periods you can specify how many iterations you want. Reading more than once will usually return a more precise value however, sometimes it will take longer.

float getRmsVoltage(uint16_t frequency, uint8_t loopCount)

This method allows us to specify the input voltage frequency, from which the measurement period is derived, at the time of measurement.

Set Sensitivity

void setSensitivity(float value)

This method sets the sensitivity value of the sensor. The Sensitivity is the ratio of the output voltage sensor (that read by the ADC) to the input voltage sensor. The default value of sensitivity is 500.0.

Example

Circuit

⚠️ If you are using a board with a 3.3 Volt system you should connect VCC to 3.3 Volt (eg ESP board family).

Steep

0. Make sure the output voltage from the sensor is not clipped and distorted

Connect the sensor to the voltage source you are going to measure.

Use the following code to observe the waveform from the ZMPT1b sensor output.

void setup() {
  Serial.begin(115200);
}

void loop() {
  Serial.println(analogRead(A0));
  delayMicroseconds(1000);
}

Upload code and open serial plotter.

Rotate the trimpot on the sensor until the output is not clipped, distorted and safe enough.

1. Determine the appropriate sensitivity value

Open the calibrate.ino example and change the ACTUAL_VOLTAGE value according to the actual AC voltage value (eg based on a measurement with a voltmeter or something else). Upload the code then open serial monitor. Wait until the sensitivity value is displayed and then copy it.

2. Start measurement

Open either the simple_usage.ino example then change the SENSITIVITY value (seventh line) based on the value you got in the previous process or use the alternate constructor in the alternate_usage.ino example to set the sensitivity in the sensor constructor. Upload the code then open the serial monitor to observe the displayed voltage value.