koltesdigital / hmc5883l.c

Simple wrapper for HMC5883L compass on I2C.

HMC5883L.c

Simple wrapper for HMC5883L compass on I2C.

Tested on a Raspberry Pi 2.

Build

Build, and optionally install, with scons.

scons
sudo scons install

Usage

All functions take a file handle as first parameter (obtained with open and released with close), and return 0 when successful or -1 on failure.

Example:

static int file;

static int closeAndExit(int code)
{
	close(file);
	return code;
}

int main(void)
{
	file = open("/dev/i2c-1", O_RDWR);
	if (file < 0)
		return -1;

	if (HMC5883L_Init(file, HMC5883L_ID, true))
		return closeAndExit(-1);

    struct HMC5883L conf = {
        .gain = HMC5883L_GAIN_1090,
        .measurementMode = HMC5883L_MEASUREMENTMODE_NORMAL,
        .outputRate = HMC5883L_OUTPUTRATE_30,
        .samples = HMC5883L_SAMPLES_2,
    };
    if (HMC5883L_Configure(file, &conf))
		return closeAndExit(-1);

    if (HMC5883L_SetContinuousMeasurement(file))
		return closeAndExit(-1);

	short x, y, z;
	if (HMC5883L_ReadData(file, &x, &y, &z))
		return closeAndExit(-1);

	return closeAndExit(0);
}

HMC5883L_Init(int file, unsigned char id, bool check)

id is the device I2C address. It is usually HMC5883L_ID (0x1E).

If check is true, the function reads the device identification registers and checks against the expected values. This inherently checks that the device and the I2C bus are working.

License

Copyright 2016 Bloutiouf

MIT License