openpilot is an open source driver assistance system. openpilot performs the functions of Automated Lane Centering and Adaptive Cruise Control for over 200 supported car makes and models.
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#include "bmx055_accel.h"
#include <cassert>
#include "common/swaglog.h"
#include "common/timing.h"
BMX055_Accel::BMX055_Accel(I2CBus *bus) : I2CSensor(bus) {}
int BMX055_Accel::init() {
int ret = 0;
uint8_t buffer[1];
ret = read_register(BMX055_ACCEL_I2C_REG_ID, buffer, 1);
if(ret < 0) {
LOGE("Reading chip ID failed: %d", ret);
goto fail;
}
if(buffer[0] != BMX055_ACCEL_CHIP_ID) {
LOGE("Chip ID wrong. Got: %d, Expected %d", buffer[0], BMX055_ACCEL_CHIP_ID);
ret = -1;
goto fail;
}
// High bandwidth
// ret = set_register(BMX055_ACCEL_I2C_REG_HBW, BMX055_ACCEL_HBW_ENABLE);
// if (ret < 0) {
// goto fail;
// }
// Low bandwidth
ret = set_register(BMX055_ACCEL_I2C_REG_HBW, BMX055_ACCEL_HBW_DISABLE);
if (ret < 0) {
goto fail;
}
ret = set_register(BMX055_ACCEL_I2C_REG_BW, BMX055_ACCEL_BW_125HZ);
if (ret < 0) {
goto fail;
}
fail:
return ret;
}
void BMX055_Accel::get_event(cereal::SensorEventData::Builder &event) {
uint64_t start_time = nanos_since_boot();
uint8_t buffer[6];
int len = read_register(BMX055_ACCEL_I2C_REG_X_LSB, buffer, sizeof(buffer));
assert(len == 6);
// 12 bit = +-2g
float scale = 9.81 * 2.0f / (1 << 11);
float x = -read_12_bit(buffer[0], buffer[1]) * scale;
float y = -read_12_bit(buffer[2], buffer[3]) * scale;
float z = read_12_bit(buffer[4], buffer[5]) * scale;
event.setSource(cereal::SensorEventData::SensorSource::BMX055);
event.setVersion(1);
event.setSensor(SENSOR_ACCELEROMETER);
event.setType(SENSOR_TYPE_ACCELEROMETER);
event.setTimestamp(start_time);
float xyz[] = {x, y, z};
auto svec = event.initAcceleration();
svec.setV(xyz);
svec.setStatus(true);
}