ardupilot/libraries/AP_InertialSensor/AP_InertialSensor_Oilpan.cpp

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/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
#include <AP_HAL/AP_HAL.h>
#if CONFIG_HAL_BOARD == HAL_BOARD_APM1
#include "AP_InertialSensor_Oilpan.h"
#include <AP_ADC/AP_ADC.h>
const extern AP_HAL::HAL& hal;
// this driver assumes an AP_ADC object has been declared globally
extern AP_ADC_ADS7844 apm1_adc;
// ADC channel mappings on for the APM Oilpan
// Sensors: GYROX, GYROY, GYROZ, ACCELX, ACCELY, ACCELZ
const uint8_t AP_InertialSensor_Oilpan::_sensors[6] = { 1, 2, 0, 4, 5, 6 };
// ADC result sign adjustment for sensors.
const int8_t AP_InertialSensor_Oilpan::_sensor_signs[6] =
{ 1, -1, -1, 1, -1, -1 };
// Maximum possible value returned by an offset-corrected sensor channel
const float AP_InertialSensor_Oilpan::_adc_constraint = 900;
// ADC : Voltage reference 3.3v / 12bits(4096 steps) => 0.8mV/ADC step
// ADXL335 Sensitivity(from datasheet) => 330mV/g,
// 0.8mV/ADC step => 330/0.8 = 412
// Tested value : 418
// Oilpan accelerometer scaling & offsets
#define OILPAN_ACCEL_SCALE_1G (GRAVITY_MSS * 2.0f / (2465.0f - 1617.0f))
#define OILPAN_RAW_ACCEL_OFFSET ((2465.0f + 1617.0f) * 0.5f)
#define OILPAN_RAW_GYRO_OFFSET 1658.0f
// IDG500 Sensitivity (from datasheet) => 2.0mV/degree/s,
// 0.8mV/ADC step => 0.8/3.33 = 0.4
// Tested values : 0.4026, ?, 0.4192
const float AP_InertialSensor_Oilpan::_gyro_gain_x = radians(0.4f);
const float AP_InertialSensor_Oilpan::_gyro_gain_y = radians(0.41f);
const float AP_InertialSensor_Oilpan::_gyro_gain_z = radians(0.41f);
/* ------ Public functions -------------------------------------------*/
AP_InertialSensor_Oilpan::AP_InertialSensor_Oilpan(AP_InertialSensor &imu) :
AP_InertialSensor_Backend(imu)
{
}
/*
detect the sensor
*/
AP_InertialSensor_Backend *AP_InertialSensor_Oilpan::detect(AP_InertialSensor &_imu)
{
AP_InertialSensor_Oilpan *sensor = new AP_InertialSensor_Oilpan(_imu);
if (sensor == NULL) {
return NULL;
}
if (!sensor->_init_sensor()) {
delete sensor;
return NULL;
}
return sensor;
}
bool AP_InertialSensor_Oilpan::_init_sensor(void)
{
apm1_adc.Init();
switch (_imu.get_sample_rate()) {
case AP_InertialSensor::RATE_50HZ:
_sample_threshold = 20;
break;
case AP_InertialSensor::RATE_100HZ:
_sample_threshold = 10;
break;
case AP_InertialSensor::RATE_200HZ:
_sample_threshold = 5;
break;
default:
// can't do this speed
return false;
}
_gyro_instance = _imu.register_gyro();
_accel_instance = _imu.register_accel();
_product_id = AP_PRODUCT_ID_APM1_2560;
return true;
}
/*
copy data from ADC to frontend
*/
bool AP_InertialSensor_Oilpan::update()
{
float adc_values[6];
apm1_adc.Ch6(_sensors, adc_values);
// copy gyros to frontend
Vector3f v;
v(_sensor_signs[0] * ( adc_values[0] - OILPAN_RAW_GYRO_OFFSET ) * _gyro_gain_x,
_sensor_signs[1] * ( adc_values[1] - OILPAN_RAW_GYRO_OFFSET ) * _gyro_gain_y,
_sensor_signs[2] * ( adc_values[2] - OILPAN_RAW_GYRO_OFFSET ) * _gyro_gain_z);
_rotate_and_correct_gyro(_gyro_instance, v);
_publish_gyro(_gyro_instance, v);
// copy accels to frontend
v(_sensor_signs[3] * (adc_values[3] - OILPAN_RAW_ACCEL_OFFSET),
_sensor_signs[4] * (adc_values[4] - OILPAN_RAW_ACCEL_OFFSET),
_sensor_signs[5] * (adc_values[5] - OILPAN_RAW_ACCEL_OFFSET));
v *= OILPAN_ACCEL_SCALE_1G;
_rotate_and_correct_accel(_accel_instance, v);
_publish_accel(_accel_instance, v);
return true;
}
// return true if a new sample is available
bool AP_InertialSensor_Oilpan::_sample_available() const
{
return apm1_adc.num_samples_available(_sensors) >= _sample_threshold;
}
#endif // CONFIG_HAL_BOARD