mongoose-os-libs/ina219-i2c

INA219 I2C Driver

A Mongoose library for Texas Instruments' popular I2C current sensor.

Implementation details

The INA219 is a simple I2C device that measures a voltage drop over a shunt resistor, as well as the voltage on the bus. It is able to measure voltage up to 26V (in 4mV increments) on the bus and the voltage drop over the shunt resistor in 10uV increments with a range of 320mV, and is reasonably precise.

Using a 0.1Ohm shunt resistor, the maximum current that can be measured is 3.2A.

API Description

Create an INA219 object using mgos_ina219_create(), set the shunt resistor value using mgos_ina219_set_shunt_resistance(), then call mgos_ina219_get_bus_voltage() to get the bus voltage, call mgos_ina219_get_shunt_voltage() to get the voltage drop over the shunt resistor, and mgos_ina219_get_current() to get the current flowing through the circuit.

Example application

#include "mgos.h"
#include "mgos_config.h"
#include "mgos_ina219.h"

static void ina219_timer_cb(void *user_data) {
  struct mgos_ina219 *sensor = (struct mgos_ina219 *)user_data;
  float bus, shunt, current, res;

  if (!sensor) return;

  mgos_ina219_get_bus_voltage(sensor, &bus);
  mgos_ina219_get_shunt_resistance(sensor, &res);
  mgos_ina219_get_shunt_voltage(sensor, &shunt);
  mgos_ina219_get_current(sensor, &current);
  LOG(LL_INFO, ("Vbus=%.3f V Vshunt=%.0f uV Rshunt=%.3f Ohm Ishunt=%.1f mA",
      bus, shunt*1e6, res, current*1e3));
  }
}

enum mgos_app_init_result mgos_app_init(void) {
  struct mgos_ina219 *sensor;

  sensor = mgos_ina219_create(mgos_i2c_get_global(), mgos_sys_config_get_ina219_i2caddr());
  if (!sensor) {
    LOG(LL_ERROR, ("Could not create INA219 sensor"));
    return false;
  }

  mgos_set_timer(1000, true, ina219_timer_cb, sensor);

  return MGOS_APP_INIT_SUCCESS;
}

Disclaimer

This project is not an official Google project. It is not supported by Google and Google specifically disclaims all warranties as to its quality, merchantability, or fitness for a particular purpose.