95 lines
2.3 KiB
C++
95 lines
2.3 KiB
C++
#include "maa.h"
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#include "math.h"
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#define MAX_BUFFER_LENGTH 6
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#define HMC5883L_I2C_ADDR 0x1E
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//configuration registers
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#define HMC5883L_CONF_REG_A 0x00
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#define HMC5883L_CONF_REG_B 0x01
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//mode register
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#define HMC5883L_MODE_REG 0x02
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//data register
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#define HMC5883L_X_MSB_REG 0
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#define HMC5883L_X_LSB_REG 1
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#define HMC5883L_Z_MSB_REG 2
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#define HMC5883L_Z_LSB_REG 3
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#define HMC5883L_Y_MSB_REG 4
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#define HMC5883L_Y_LSB_REG 5
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#define DATA_REG_SIZE 6
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//status register
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#define HMC5883L_STATUS_REG 0x09
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//ID registers
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#define HMC5883L_ID_A_REG 0x0A
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#define HMC5883L_ID_B_REG 0x0B
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#define HMC5883L_ID_C_REG 0x0C
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#define HMC5883L_CONT_MODE 0x00
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#define HMC5883L_DATA_REG 0x03
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//scales
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#define GA_0_88_REG 0x00 << 5
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#define GA_1_3_REG 0x01 << 5
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#define GA_1_9_REG 0x02 << 5
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#define GA_2_5_REG 0x03 << 5
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#define GA_4_0_REG 0x04 << 5
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#define GA_4_7_REG 0x05 << 5
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#define GA_5_6_REG 0x06 << 5
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#define GA_8_1_REG 0x07 << 5
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//digital resolutions
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#define SCALE_0_73_MG 0.73
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#define SCALE_0_92_MG 0.92
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#define SCALE_1_22_MG 1.22
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#define SCALE_1_52_MG 1.52
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#define SCALE_2_27_MG 2.27
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#define SCALE_2_56_MG 2.56
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#define SCALE_3_03_MG 3.03
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#define SCALE_4_35_MG 4.35
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int
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main ()
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{
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float direction = 0;
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int16_t x = 0, y = 0, z = 0;
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char rx_tx_buf[MAX_BUFFER_LENGTH];
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maa::I2CSlave i2c(26, 27);
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i2c.address(HMC5883L_I2C_ADDR);
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rx_tx_buf[0] = HMC5883L_CONF_REG_B;
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rx_tx_buf[1] = GA_1_3_REG;
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i2c.write(rx_tx_buf, 2);
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i2c.address(HMC5883L_I2C_ADDR);
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rx_tx_buf[0] = HMC5883L_MODE_REG;
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rx_tx_buf[1] = HMC5883L_CONT_MODE;
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i2c.write(rx_tx_buf, 2);
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for(;;) {
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i2c.address(HMC5883L_I2C_ADDR);
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i2c.write(HMC5883L_DATA_REG);
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i2c.address(HMC5883L_I2C_ADDR);
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i2c.read(rx_tx_buf, DATA_REG_SIZE);
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x = (rx_tx_buf[HMC5883L_X_MSB_REG] << 8 ) | rx_tx_buf[HMC5883L_X_LSB_REG] ;
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z = (rx_tx_buf[HMC5883L_Z_MSB_REG] << 8 ) | rx_tx_buf[HMC5883L_Z_LSB_REG] ;
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y = (rx_tx_buf[HMC5883L_Y_MSB_REG] << 8 ) | rx_tx_buf[HMC5883L_Y_LSB_REG] ;
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//scale and calculate direction
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direction = atan2(y * SCALE_0_92_MG, x * SCALE_0_92_MG);
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//check if the signs are reversed
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if (direction < 0)
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direction += 2 * M_PI;
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printf("Compass scaled data x : %f, y : %f, z : %f\n", x * SCALE_0_92_MG, y * SCALE_0_92_MG, z * SCALE_0_92_MG) ;
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printf("Heading : %f\n", direction * 180/M_PI) ;
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}
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}
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