Michael Ammann / INA219

The INA219 is a high-side current shunt and power monitor with an I2C interface. The INA219 monitors both shunt drop and supply voltage, with programmable conversion times and filtering. A programmable calibration value, combined with an internal multiplier, enables direct readouts in amperes. An additional multiplying register calculates power in watts. The I2C interface features 16 programmable addresses.

INA219.cpp@0:81c08f01f0fe, 2013-11-19 (annotated)

Committer:
mazgch
Date:
Tue Nov 19 05:31:39 2013 +0000
Revision:
0:81c08f01f0fe
Child:
1:2816fc874abc
draft;

Who changed what in which revision?

UserRevisionLine numberNew contents of line
mazgch 0:81c08f01f0fe 1 #include "INA219.h"
mazgch 0:81c08f01f0fe 2
mazgch 0:81c08f01f0fe 3 INA219::INA219(PinName sda, PinName scl, unsigned char adr) :
mazgch 0:81c08f01f0fe 4 _i2c(sda, scl)
mazgch 0:81c08f01f0fe 5 {
mazgch 0:81c08f01f0fe 6 _i2c.frequency(100000);
mazgch 0:81c08f01f0fe 7 _adr = adr;
mazgch 0:81c08f01f0fe 8 }
mazgch 0:81c08f01f0fe 9
mazgch 0:81c08f01f0fe 10 bool INA219::detect(void)
mazgch 0:81c08f01f0fe 11 {
mazgch 0:81c08f01f0fe 12 _i2c.start();
mazgch 0:81c08f01f0fe 13 _adr = (1 == _i2c.write(_adr|1/*write address for reading*/));
mazgch 0:81c08f01f0fe 14 _i2c.stop();
mazgch 0:81c08f01f0fe 15 return _det;
mazgch 0:81c08f01f0fe 16 }
mazgch 0:81c08f01f0fe 17
mazgch 0:81c08f01f0fe 18 double INA219::getCurrent(void)
mazgch 0:81c08f01f0fe 19 {
mazgch 0:81c08f01f0fe 20 double d = 0.0;
mazgch 0:81c08f01f0fe 21 if (_det)
mazgch 0:81c08f01f0fe 22 {
mazgch 0:81c08f01f0fe 23 char r = 0x01;
mazgch 0:81c08f01f0fe 24 if (0 == _i2c.write(_adr, &r, sizeof(r), true))
mazgch 0:81c08f01f0fe 25 {
mazgch 0:81c08f01f0fe 26 char v[2] = {0};
mazgch 0:81c08f01f0fe 27 if (0 == _i2c.read(_adr, v, sizeof(v)))
mazgch 0:81c08f01f0fe 28 {
mazgch 0:81c08f01f0fe 29 int u = (int)((((short)v[0]) << 8) + (unsigned char)v[1]) * 10; // uV
mazgch 0:81c08f01f0fe 30 int i = u * 2/*0.5ohm*/;
mazgch 0:81c08f01f0fe 31 d = 1e-6 * i;
mazgch 0:81c08f01f0fe 32 }
mazgch 0:81c08f01f0fe 33 }
mazgch 0:81c08f01f0fe 34 else
mazgch 0:81c08f01f0fe 35 _i2c.stop();
mazgch 0:81c08f01f0fe 36 }
mazgch 0:81c08f01f0fe 37 return d;
mazgch 0:81c08f01f0fe 38 }
mazgch 0:81c08f01f0fe 39
mazgch 0:81c08f01f0fe 40 double INA219::getVoltage(void)
mazgch 0:81c08f01f0fe 41 {
mazgch 0:81c08f01f0fe 42 double d = 0.0;
mazgch 0:81c08f01f0fe 43 if (_det)
mazgch 0:81c08f01f0fe 44 {
mazgch 0:81c08f01f0fe 45 char r = 0x02;
mazgch 0:81c08f01f0fe 46 if (0 == _i2c.write(_adr, &r, sizeof(r), true))
mazgch 0:81c08f01f0fe 47 {
mazgch 0:81c08f01f0fe 48 char v[2] = {0};
mazgch 0:81c08f01f0fe 49 if (0 == _i2c.read(_adr, v, sizeof(v)))
mazgch 0:81c08f01f0fe 50 {
mazgch 0:81c08f01f0fe 51 int u = (int)(((((short)v[0]) << 8) + (unsigned char)v[1]) >> 3) * 4; // mV
mazgch 0:81c08f01f0fe 52 d = 1e-3 * u;
mazgch 0:81c08f01f0fe 53 }
mazgch 0:81c08f01f0fe 54 }
mazgch 0:81c08f01f0fe 55 else
mazgch 0:81c08f01f0fe 56 _i2c.stop();
mazgch 0:81c08f01f0fe 57 }
mazgch 0:81c08f01f0fe 58 return d;
mazgch 0:81c08f01f0fe 59 }