Posted on August 01, 2017 at 18:56Hi all,
I am evaluating the LPS25HB pressure sensor on iMX6 host processor, I am interested in getting the altitude for our usecase.
The problem is I am getting consistent value of pressure with no change even when I moved from floor to floor in the elevator. Can someone help me in solving this issue?
Here is the simple code which I am using:
const double read_pressure(void)
{
double pressure = 0.0;
int pres_raw = 0;
unsigned char pdataReady = 0;
qDebug() << Q_FUNC_INFO << 'entry';
pdataReady = i2c_smbus_read_byte_data(file_i2c, LPS25HB_STATUS_REG);
while(!(pdataReady & 0x02))
pdataReady = i2c_smbus_read_byte_data(file_i2c, LPS25HB_STATUS_REG); //loop until pressure data is ready
pres_raw = i2c_smbus_read_byte_data(file_i2c, LPS25HB_PRESS_OUT_XL);
pres_raw |= (int32_t) i2c_smbus_read_byte_data(file_i2c, LPS25HB_PRESS_OUT_L) << 8;
pres_raw |= (int32_t) i2c_smbus_read_byte_data(file_i2c, LPS25HB_PRESS_OUT_H) << 16;
qDebug() << Q_FUNC_INFO << pres_raw;
pressure = pres_raw / 4096.0;
return pressure;
}
int main(int argc, char *argv[])
{
int i;
int alti;
unsigned char txBuff[5];
unsigned char rxBuff[32] = {0};
unsigned char tmp;
//altimeter_init(LPS25HB_ODR_7HZ);
file_i2c = open('/dev/i2c-2', O_RDWR);
file_ioc = ioctl(file_i2c, I2C_SLAVE, 0x5d);
tmp = i2c_smbus_read_byte_data(file_i2c, LPS25HB_WHO_AM_I_REG);
qDebug() << Q_FUNC_INFO << 'client_id' << tmp;
tmp = LPS25HB_PD_MASK;
tmp |= LPS25HB_BDU_MASK;
tmp |= 0x20; // set ODR to 7HZ
i2c_smbus_write_byte_data(file_i2c, LPS25HB_CTRL_REG1, tmp);
tmp = 0x0F; // set resolution of pressure to 512
i2c_smbus_write_byte_data(file_i2c, LPS25HB_RES_CONF, tmp);
while(1){
qDebug() << Q_FUNC_INFO << read_pressure();
}
return 0;
}
Output :
I always get the constant value even if I go DOWN and UP in the elevator
const double read_pressure() 12582912
int main(int, char**) 3072
