PNI RM3000-F Sensor Suite - Manual (Page 44)

PNI Sensor Corporation Doc #1016102 r04
RM3000-f & RM2000-f Sensor Suite User Manual Page 44
/*************************************************************************
* Function Name : mag_sample
* Description : Sample the magnetic sensors and get measurement in
"count"
* Input : None
* Output : None
* Return : None
*************************************************************************/
void mag_sample(void)
{
unsigned char axis;
//
// change the phase and polarity to be 0/0
//
spi_1_go_0_phase_0_pol();
SPI_tom_CS_LOW();
usec_delay(1);
//Send 0xC9 on MOSI pin to initiate reading the measurement values
tom_first_byte=SPI_read_write(0xc9);
usec_delay(1);
//Read data from X-axis, Y-axis and Z-axis
for(axis=0;axis<3;axis++)
{
mag_raw[axis]=SPI_read_write(0)<<16;
usec_delay(1);
mag_raw[axis]|=SPI_read_write(0)<<8;
usec_delay(1);
mag_raw[axis]|=SPI_read_write(0);
//
//check the MSB and do sign extension if necessary
//
if(mag_raw[axis]&0x00800000)
{
mag_raw[axis]|=0xff000000;
}
}
SPI_tom_CS_HIGH();
usec_delay(1);
SPI_tom_CS_LOW();
usec_delay(1);
//
// change the phase and polarity to be 1/1
//
spi_1_go_1_phase_1_pol();
}