BMX055 magnetometer calibration (#19992)
Willem Melching
GitHub
parent
1588a6f0ac
commit
fd01c89491
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@ -1,5 +1,6 @@
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#include <cassert>
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#include <cstdio>
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#include <algorithm>
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#include <unistd.h>
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#include "common/swaglog.h"
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@ -7,6 +8,60 @@
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#include "bmx055_magn.hpp"
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static int16_t compensate_x(trim_data_t trim_data, int16_t mag_data_x, uint16_t data_rhall) {
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uint16_t process_comp_x0 = data_rhall;
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int32_t process_comp_x1 = ((int32_t)trim_data.dig_xyz1) * 16384;
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uint16_t process_comp_x2 = ((uint16_t)(process_comp_x1 / process_comp_x0)) - ((uint16_t)0x4000);
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int16_t retval = ((int16_t)process_comp_x2);
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int32_t process_comp_x3 = (((int32_t)retval) * ((int32_t)retval));
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int32_t process_comp_x4 = (((int32_t)trim_data.dig_xy2) * (process_comp_x3 / 128));
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int32_t process_comp_x5 = (int32_t)(((int16_t)trim_data.dig_xy1) * 128);
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int32_t process_comp_x6 = ((int32_t)retval) * process_comp_x5;
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int32_t process_comp_x7 = (((process_comp_x4 + process_comp_x6) / 512) + ((int32_t)0x100000));
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int32_t process_comp_x8 = ((int32_t)(((int16_t)trim_data.dig_x2) + ((int16_t)0xA0)));
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int32_t process_comp_x9 = ((process_comp_x7 * process_comp_x8) / 4096);
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int32_t process_comp_x10 = ((int32_t)mag_data_x) * process_comp_x9;
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retval = ((int16_t)(process_comp_x10 / 8192));
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retval = (retval + (((int16_t)trim_data.dig_x1) * 8)) / 16;
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return retval;
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}
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static int16_t compensate_y(trim_data_t trim_data, int16_t mag_data_y, uint16_t data_rhall) {
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uint16_t process_comp_y0 = trim_data.dig_xyz1;
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int32_t process_comp_y1 = (((int32_t)trim_data.dig_xyz1) * 16384) / process_comp_y0;
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uint16_t process_comp_y2 = ((uint16_t)process_comp_y1) - ((uint16_t)0x4000);
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int16_t retval = ((int16_t)process_comp_y2);
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int32_t process_comp_y3 = ((int32_t) retval) * ((int32_t)retval);
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int32_t process_comp_y4 = ((int32_t)trim_data.dig_xy2) * (process_comp_y3 / 128);
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int32_t process_comp_y5 = ((int32_t)(((int16_t)trim_data.dig_xy1) * 128));
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int32_t process_comp_y6 = ((process_comp_y4 + (((int32_t)retval) * process_comp_y5)) / 512);
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int32_t process_comp_y7 = ((int32_t)(((int16_t)trim_data.dig_y2) + ((int16_t)0xA0)));
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int32_t process_comp_y8 = (((process_comp_y6 + ((int32_t)0x100000)) * process_comp_y7) / 4096);
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int32_t process_comp_y9 = (((int32_t)mag_data_y) * process_comp_y8);
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retval = (int16_t)(process_comp_y9 / 8192);
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retval = (retval + (((int16_t)trim_data.dig_y1) * 8)) / 16;
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return retval;
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}
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static int16_t compensate_z(trim_data_t trim_data, int16_t mag_data_z, uint16_t data_rhall) {
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int16_t process_comp_z0 = ((int16_t)data_rhall) - ((int16_t) trim_data.dig_xyz1);
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int32_t process_comp_z1 = (((int32_t)trim_data.dig_z3) * ((int32_t)(process_comp_z0))) / 4;
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int32_t process_comp_z2 = (((int32_t)(mag_data_z - trim_data.dig_z4)) * 32768);
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int32_t process_comp_z3 = ((int32_t)trim_data.dig_z1) * (((int16_t)data_rhall) * 2);
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int16_t process_comp_z4 = (int16_t)((process_comp_z3 + (32768)) / 65536);
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int32_t retval = ((process_comp_z2 - process_comp_z1) / (trim_data.dig_z2 + process_comp_z4));
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/* saturate result to +/- 2 micro-tesla */
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retval = std::clamp(retval, -32767, 32767);
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/* Conversion of LSB to micro-tesla*/
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retval = retval / 16;
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return (int16_t)retval;
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}
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static int16_t parse_xy(uint8_t lsb, uint8_t msb){
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// 13 bit
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uint16_t combined = (uint16_t(msb) << 5) | uint16_t(lsb >> 3);
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@ -19,18 +74,19 @@ static int16_t parse_z(uint8_t lsb, uint8_t msb){
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return int16_t(combined << 1) / (1 << 1);
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}
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/*
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static uint16_t parse_rhall(uint8_t lsb, uint8_t msb){
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// 14 bit
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return (uint16_t(msb) << 6) | uint16_t(lsb >> 2);
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}
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*/
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BMX055_Magn::BMX055_Magn(I2CBus *bus) : I2CSensor(bus) {}
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int BMX055_Magn::init(){
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int ret;
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uint8_t buffer[1];
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uint8_t trim_x1y1[2] = {0};
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uint8_t trim_xyz_data[4] = {0};
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uint8_t trim_xy1xy2[10] = {0};
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// suspend -> sleep
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ret = set_register(BMX055_MAGN_I2C_REG_PWR_0, 0x01);
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@ -52,6 +108,37 @@ int BMX055_Magn::init(){
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return -1;
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}
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// Load magnetometer trim
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ret = read_register(BMX055_MAGN_I2C_REG_DIG_X1, trim_x1y1, 2);
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if(ret < 0){
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goto fail;
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}
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ret = read_register(BMX055_MAGN_I2C_REG_DIG_Z4, trim_xyz_data, 4);
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if(ret < 0){
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goto fail;
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}
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ret = read_register(BMX055_MAGN_I2C_REG_DIG_Z2, trim_xy1xy2, 10);
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if(ret < 0){
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goto fail;
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}
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// Read trim data
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trim_data.dig_x1 = (int8_t)trim_x1y1[0];
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trim_data.dig_y1 = (int8_t)trim_x1y1[1];
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trim_data.dig_x2 = (int8_t)trim_xyz_data[2];
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trim_data.dig_y2 = (int8_t)trim_xyz_data[3];
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trim_data.dig_z1 = read_16_bit(trim_xy1xy2[2], trim_xy1xy2[3]);
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trim_data.dig_z2 = read_16_bit(trim_xy1xy2[0], trim_xy1xy2[1]);
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trim_data.dig_z3 = read_16_bit(trim_xy1xy2[6], trim_xy1xy2[7]);
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trim_data.dig_z4 = read_16_bit(trim_xyz_data[0], trim_xyz_data[1]);
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trim_data.dig_xy1 = trim_xy1xy2[9];
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trim_data.dig_xy2 = (int8_t)trim_xy1xy2[8];
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trim_data.dig_xyz1 = read_16_bit(trim_xy1xy2[4], trim_xy1xy2[5] & 0x7f);
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// TODO: perform self-test
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// 9 REPXY and 15 REPZ for 100 Hz
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@ -82,10 +169,14 @@ void BMX055_Magn::get_event(cereal::SensorEventData::Builder &event){
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bool ready = buffer[6] & 0x1;
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if (ready){
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float x = parse_xy(buffer[0], buffer[1]);
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float y = parse_xy(buffer[2], buffer[3]);
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float z = parse_z(buffer[4], buffer[5]);
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//uint16_t rhall = parse_rhall(buffer[5], buffer[6]);
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int16_t x = parse_xy(buffer[0], buffer[1]);
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int16_t y = parse_xy(buffer[2], buffer[3]);
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int16_t z = parse_z(buffer[4], buffer[5]);
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int16_t rhall = parse_rhall(buffer[5], buffer[6]);
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x = compensate_x(trim_data, x, rhall);
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y = compensate_y(trim_data, y, rhall);
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z = compensate_z(trim_data, z, rhall);
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// TODO: convert to micro tesla:
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// https://github.com/BoschSensortec/BMM150-Sensor-API/blob/master/bmm150.c#L1614
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@ -96,7 +187,7 @@ void BMX055_Magn::get_event(cereal::SensorEventData::Builder &event){
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event.setType(SENSOR_TYPE_MAGNETIC_FIELD_UNCALIBRATED);
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event.setTimestamp(start_time);
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float xyz[] = {x, y, z};
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float xyz[] = {(float)x, (float)y, (float)z};
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auto svec = event.initMagneticUncalibrated();
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svec.setV(xyz);
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svec.setStatus(true);
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@ -14,12 +14,32 @@
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#define BMX055_MAGN_I2C_REG_REPXY 0x51
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#define BMX055_MAGN_I2C_REG_REPZ 0x52
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#define BMX055_MAGN_I2C_REG_DIG_X1 0x5D
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#define BMX055_MAGN_I2C_REG_DIG_Z4 0x62
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#define BMX055_MAGN_I2C_REG_DIG_Z2 0x68
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// Constants
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#define BMX055_MAGN_CHIP_ID 0x32
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#define BMX055_MAGN_FORCED (0b01 << 1)
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struct trim_data_t {
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int8_t dig_x1;
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int8_t dig_y1;
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int8_t dig_x2;
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int8_t dig_y2;
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uint16_t dig_z1;
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int16_t dig_z2;
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int16_t dig_z3;
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int16_t dig_z4;
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uint8_t dig_xy1;
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int8_t dig_xy2;
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uint16_t dig_xyz1;
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};
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class BMX055_Magn : public I2CSensor{
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uint8_t get_device_address() {return BMX055_MAGN_I2C_ADDR;}
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trim_data_t trim_data = {0};
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public:
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BMX055_Magn(I2CBus *bus);
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int init();
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