Hi everyone,
I tried replicating "https://jimmyutterstrom.com/blog/2015/07/12/psoc-tutorial-adafruit-lsm303-magnetometer-compass-modul... onto PSoC5LP.
I got readings from the compass module, but it is always the same value and does not change while the PSoC plugged in.
When i remove and plug in the PSoC again, the heading value changes to what is expected but it does not update when i move the compass along. I feel like there's something wrong with the I2C communication, that the value is not being updated. Any help / guidance on how to solve this issue is greatly appreciated.
#include <project.h>
#include <math.h>
#include <stdio.h>
#define LSM303_ADDRESS_ACCEL (0x32 >> 1)
#define LSM303_ADDRESS_MAG (0x3C >> 1)
#define LSM303_REGISTER_ACCEL_CTRL_REG1_A 0x20
#define LSM303_REGISTER_MAG_MR_REG_M 0x02
#define LSM303_REGISTER_MAG_OUT_X_H_M 0x03
#define LSM303_REGISTER_ACCEL_OUT_X_L_A 0x28
typedef struct Vector3{
int x;
int y;
int z;
} Vector3;
void LSM303_Init() {
//Start the I2C component.
LSM303_I2C_Start();
/*------------ Accelerometer ------------*/
//Send start command for write mode.
LSM303_I2C_MasterSendStart(LSM303_ADDRESS_ACCEL, LSM303_I2C_WRITE_XFER_MODE);
//Specify which register we want to write to.
//This register is written to for enabling x, y and z
//output as well as setting datarate and powermode.
LSM303_I2C_MasterWriteByte(LSM303_REGISTER_ACCEL_CTRL_REG1_A);
//Set the required bits in the register.
LSM303_I2C_MasterWriteByte(0x27u);
/*------------ Magnetometer ------------*/
//This register is written to for setting data output rates
//and controlling measurement flow.
LSM303_I2C_MasterWriteByte(LSM303_REGISTER_MAG_MR_REG_M);
LSM303_I2C_MasterWriteByte(0x00u);
LSM303_I2C_MasterSendStop();
}
void LSM303_ReadMag(Vector3 *magData) {
uint8 data[6];
//Prepare the module for magnetometer output.
LSM303_I2C_MasterSendStart(LSM303_ADDRESS_MAG, LSM303_I2C_WRITE_XFER_MODE);
LSM303_I2C_MasterWriteByte(LSM303_REGISTER_MAG_OUT_X_H_M);
LSM303_I2C_MasterSendStop();
//--
//Start the communication in read mode.
LSM303_I2C_MasterSendStart(LSM303_ADDRESS_MAG, LSM303_I2C_READ_XFER_MODE);
//Read databytes.
data[0] = LSM303_I2C_MasterReadByte(LSM303_I2C_ACK_DATA);
data[1] = LSM303_I2C_MasterReadByte(LSM303_I2C_ACK_DATA);
data[2] = LSM303_I2C_MasterReadByte(LSM303_I2C_ACK_DATA);
data[3] = LSM303_I2C_MasterReadByte(LSM303_I2C_ACK_DATA);
data[4] = LSM303_I2C_MasterReadByte(LSM303_I2C_ACK_DATA);
//Notice that we are here using "NAK_DATA". It's to tell the
//LSM303 that we're done and don't want to read anymore data.
data[5] = LSM303_I2C_MasterReadByte(LSM303_I2C_NAK_DATA);
//Put together the different data bytes to form complete
//integers for storing the output values.
magData->x = (int16_t)(data[1] | (data[0] << 8));
magData->y = (int16_t)(data[5] | (data[4] << 8));
magData->z = (int16_t)(data[3] | (data[2] << 8));
LSM303_I2C_MasterSendStop();
}
int main()
{
Vector3 magData;
char output[4]; //String for storing uart output.
PC_UART_Start();
LSM303_Init();
for(;;)
{
LSM303_ReadMag(&magData);
//Calculate heading using arctan on the Y and X vectors.
//And convert from radians to degrees.
float h = (atan2(magData.y, magData.x) * 180.0) / 3.14159265359;
//Map the value to comply with the standard system where the heading
//is specified as an angle between 0 - 360 degrees.
if(h < 0) {
h = 360 + h;
}
//Output the heading through our UART component.
sprintf(output, "%i\r\n", (int)(h+0.5));
PC_UART_PutString(output);
//Update heading at 1 Hz
CyDelay(1000);
}
}
/* [] END OF FILE */
