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ardupilot/libraries/AP_InertialSensor/AP_InertialSensor_Flymaple.cpp

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/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
/*
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*
Flymaple IMU driver by Mike McCauley
*/
// Interface to the Flymaple sensors:
// ITG3205 Gyroscope http://www.sparkfun.com/datasheets/Sensors/Gyro/PS-ITG-3200-00-01.4.pdf
// ADXL345 Accelerometer http://www.analog.com/static/imported-files/data_sheets/ADXL345.pdf
#include <AP_HAL.h>
#if CONFIG_HAL_BOARD == HAL_BOARD_FLYMAPLE
#include "AP_InertialSensor_Flymaple.h"
const extern AP_HAL::HAL& hal;
// This is how often we wish to make raw samples of the sensors in Hz
const uint32_t raw_sample_rate_hz = 800;
// And the equivalent time between samples in microseconds
const uint32_t raw_sample_interval_us = (1000000 / raw_sample_rate_hz);
///////
/// Accelerometer ADXL345 register definitions
#define FLYMAPLE_ACCELEROMETER_ADDRESS 0x53
#define FLYMAPLE_ACCELEROMETER_XL345_DEVID 0xe5
#define FLYMAPLE_ACCELEROMETER_ADXLREG_BW_RATE 0x2c
#define FLYMAPLE_ACCELEROMETER_ADXLREG_POWER_CTL 0x2d
#define FLYMAPLE_ACCELEROMETER_ADXLREG_DATA_FORMAT 0x31
#define FLYMAPLE_ACCELEROMETER_ADXLREG_DEVID 0x00
#define FLYMAPLE_ACCELEROMETER_ADXLREG_DATAX0 0x32
#define FLYMAPLE_ACCELEROMETER_GRAVITY 248
// ADXL345 accelerometer scaling
// Result will be scaled to 1m/s/s
// ADXL345 in Full resolution mode (any g scaling) is 256 counts/g, so scale by 9.81/256 = 0.038320312
#define FLYMAPLE_ACCELEROMETER_SCALE_M_S (GRAVITY_MSS / 256.0f)
/// Gyro ITG3205 register definitions
#define FLYMAPLE_GYRO_ADDRESS 0x68
#define FLYMAPLE_GYRO_WHO_AM_I 0x00
#define FLYMAPLE_GYRO_PWR_MGM 0x3e
#define FLYMAPLE_GYRO_DLPF_FS 0x16
#define FLYMAPLE_GYRO_INT_CFG 0x17
#define FLYMAPLE_GYRO_SMPLRT_DIV 0x15
#define FLYMAPLE_GYRO_GYROX_H 0x1d
// ITG3200 Gyroscope scaling
// ITG3200 is 14.375 LSB degrees/sec with FS_SEL=3
// Result wil be radians/sec
#define FLYMAPLE_GYRO_SCALE_R_S (1.0f / 14.375f) * (3.1415926f / 180.0f)
AP_InertialSensor_Flymaple::AP_InertialSensor_Flymaple(AP_InertialSensor &imu) :
AP_InertialSensor_Backend(imu),
_have_gyro_sample(false),
_have_accel_sample(false),
_accel_filter_x(raw_sample_rate_hz, 10),
_accel_filter_y(raw_sample_rate_hz, 10),
_accel_filter_z(raw_sample_rate_hz, 10),
_gyro_filter_x(raw_sample_rate_hz, 10),
_gyro_filter_y(raw_sample_rate_hz, 10),
_gyro_filter_z(raw_sample_rate_hz, 10),
_last_gyro_timestamp(0),
_last_accel_timestamp(0)
{}
/*
detect the sensor
*/
AP_InertialSensor_Backend *AP_InertialSensor_Flymaple::detect(AP_InertialSensor &_imu)
{
AP_InertialSensor_Flymaple *sensor = new AP_InertialSensor_Flymaple(_imu);
if (sensor == NULL) {
return NULL;
}
if (!sensor->_init_sensor()) {
delete sensor;
return NULL;
}
return sensor;
}
bool AP_InertialSensor_Flymaple::_init_sensor(void)
{
_default_filter_hz = _default_filter();
// get pointer to i2c bus semaphore
AP_HAL::Semaphore* i2c_sem = hal.i2c->get_semaphore();
// take i2c bus sempahore
if (!i2c_sem->take(HAL_SEMAPHORE_BLOCK_FOREVER))
return false;
// Init the accelerometer
uint8_t data;
hal.i2c->readRegister(FLYMAPLE_ACCELEROMETER_ADDRESS, FLYMAPLE_ACCELEROMETER_ADXLREG_DEVID, &data);
if (data != FLYMAPLE_ACCELEROMETER_XL345_DEVID)
hal.scheduler->panic(PSTR("AP_InertialSensor_Flymaple: could not find ADXL345 accelerometer sensor"));
hal.i2c->writeRegister(FLYMAPLE_ACCELEROMETER_ADDRESS, FLYMAPLE_ACCELEROMETER_ADXLREG_POWER_CTL, 0x00);
hal.scheduler->delay(5);
hal.i2c->writeRegister(FLYMAPLE_ACCELEROMETER_ADDRESS, FLYMAPLE_ACCELEROMETER_ADXLREG_POWER_CTL, 0xff);
hal.scheduler->delay(5);
// Measure mode:
hal.i2c->writeRegister(FLYMAPLE_ACCELEROMETER_ADDRESS, FLYMAPLE_ACCELEROMETER_ADXLREG_POWER_CTL, 0x08);
hal.scheduler->delay(5);
// Full resolution, 8g:
// Caution, this must agree with FLYMAPLE_ACCELEROMETER_SCALE_1G
// In full resoution mode, the scale factor need not change
hal.i2c->writeRegister(FLYMAPLE_ACCELEROMETER_ADDRESS, FLYMAPLE_ACCELEROMETER_ADXLREG_DATA_FORMAT, 0x08);
hal.scheduler->delay(5);
// Normal power, 800Hz Output Data Rate, 400Hz bandwidth:
hal.i2c->writeRegister(FLYMAPLE_ACCELEROMETER_ADDRESS, FLYMAPLE_ACCELEROMETER_ADXLREG_BW_RATE, 0x0d);
hal.scheduler->delay(5);
// Power up default is FIFO bypass mode. FIFO is not used by the chip
// Init the Gyro
// Expect to read the same as the Gyro I2C adress:
hal.i2c->readRegister(FLYMAPLE_GYRO_ADDRESS, FLYMAPLE_GYRO_WHO_AM_I, &data);
if (data != FLYMAPLE_GYRO_ADDRESS)
hal.scheduler->panic(PSTR("AP_InertialSensor_Flymaple: could not find ITG-3200 accelerometer sensor"));
hal.i2c->writeRegister(FLYMAPLE_GYRO_ADDRESS, FLYMAPLE_GYRO_PWR_MGM, 0x00);
hal.scheduler->delay(1);
// Sample rate divider: with 8kHz internal clock (see FLYMAPLE_GYRO_DLPF_FS),
// get 500Hz sample rate, 2 samples
hal.i2c->writeRegister(FLYMAPLE_GYRO_ADDRESS, FLYMAPLE_GYRO_SMPLRT_DIV, 0x0f);
hal.scheduler->delay(1);
// 2000 degrees/sec, 256Hz LPF, 8kHz internal sample rate
// This is the least amount of filtering we can configure for this device
hal.i2c->writeRegister(FLYMAPLE_GYRO_ADDRESS, FLYMAPLE_GYRO_DLPF_FS, 0x18);
hal.scheduler->delay(1);
// No interrupts
hal.i2c->writeRegister(FLYMAPLE_GYRO_ADDRESS, FLYMAPLE_GYRO_INT_CFG, 0x00);
hal.scheduler->delay(1);
// Set up the filter desired
_set_filter_frequency(_imu.get_filter());
// give back i2c semaphore
i2c_sem->give();
_gyro_instance = _imu.register_gyro();
_accel_instance = _imu.register_accel();
_product_id = AP_PRODUCT_ID_FLYMAPLE;
return true;
}
/*
set the filter frequency
*/
void AP_InertialSensor_Flymaple::_set_filter_frequency(uint8_t filter_hz)
{
if (filter_hz == 0)
filter_hz = _default_filter_hz;
_accel_filter_x.set_cutoff_frequency(raw_sample_rate_hz, filter_hz);
_accel_filter_y.set_cutoff_frequency(raw_sample_rate_hz, filter_hz);
_accel_filter_z.set_cutoff_frequency(raw_sample_rate_hz, filter_hz);
_gyro_filter_x.set_cutoff_frequency(raw_sample_rate_hz, filter_hz);
_gyro_filter_y.set_cutoff_frequency(raw_sample_rate_hz, filter_hz);
_gyro_filter_z.set_cutoff_frequency(raw_sample_rate_hz, filter_hz);
}
// This takes about 20us to run
bool AP_InertialSensor_Flymaple::update(void)
{
Vector3f accel, gyro;
hal.scheduler->suspend_timer_procs();
accel = _accel_filtered;
gyro = _gyro_filtered;
_have_gyro_sample = false;
_have_accel_sample = false;
hal.scheduler->resume_timer_procs();
// Adjust for chip scaling to get m/s/s
accel *= FLYMAPLE_ACCELEROMETER_SCALE_M_S;
_rotate_and_offset_accel(_accel_instance, accel);
// Adjust for chip scaling to get radians/sec
gyro *= FLYMAPLE_GYRO_SCALE_R_S;
_rotate_and_offset_gyro(_gyro_instance, gyro);
if (_last_filter_hz != _imu.get_filter()) {
_set_filter_frequency(_imu.get_filter());
_last_filter_hz = _imu.get_filter();
}
return true;
}
// This needs to get called as often as possible.
// Its job is to accumulate samples as fast as is reasonable for the accel and gyro
// sensors.
// Note that this is called from gyro_sample_available() and
// accel_sample_available(), which is really not good enough for
// 800Hz, as it is common for the main loop to take more than 1.5ms
// before wait_for_sample() is called again. We can't just call this
// from a timer as timers run with interrupts disabled, and the I2C
// operations take too long
// So we are stuck with a suboptimal solution. The results are not so
// good in terms of timing. It may be better with the FIFOs enabled
void AP_InertialSensor_Flymaple::_accumulate(void)
{
// get pointer to i2c bus semaphore
AP_HAL::Semaphore* i2c_sem = hal.i2c->get_semaphore();
// take i2c bus sempahore
if (!i2c_sem->take(HAL_SEMAPHORE_BLOCK_FOREVER))
return;
// Read accelerometer
// ADXL345 is in the default FIFO bypass mode, so the FIFO is not used
uint8_t buffer[6];
uint32_t now = hal.scheduler->micros();
// This takes about 250us at 400kHz I2C speed
if ((now - _last_accel_timestamp) >= raw_sample_interval_us
&& hal.i2c->readRegisters(FLYMAPLE_ACCELEROMETER_ADDRESS, FLYMAPLE_ACCELEROMETER_ADXLREG_DATAX0, 6, buffer) == 0)
{
// The order is a bit wierd here since the standard we have adopted for Flymaple
// sensor orientation is different to what the board designers intended
// Caution, to support alternative chip orientations on other bords, may
// need to add a chip orientation rotate
int16_t y = -((((int16_t)buffer[1]) << 8) | buffer[0]); // chip X axis
int16_t x = -((((int16_t)buffer[3]) << 8) | buffer[2]); // chip Y axis
int16_t z = -((((int16_t)buffer[5]) << 8) | buffer[4]); // chip Z axis
_accel_filtered = Vector3f(_accel_filter_x.apply(x),
_accel_filter_y.apply(y),
_accel_filter_z.apply(z));
_have_accel_sample = true;
_last_accel_timestamp = now;
}
// Read gyro
now = hal.scheduler->micros();
// This takes about 250us at 400kHz I2C speed
if ((now - _last_gyro_timestamp) >= raw_sample_interval_us
&& hal.i2c->readRegisters(FLYMAPLE_GYRO_ADDRESS, FLYMAPLE_GYRO_GYROX_H, 6, buffer) == 0)
{
// See above re order of samples in buffer
int16_t y = -((((int16_t)buffer[0]) << 8) | buffer[1]); // chip X axis
int16_t x = -((((int16_t)buffer[2]) << 8) | buffer[3]); // chip Y axis
int16_t z = -((((int16_t)buffer[4]) << 8) | buffer[5]); // chip Z axis
_gyro_filtered = Vector3f(_gyro_filter_x.apply(x),
_gyro_filter_y.apply(y),
_gyro_filter_z.apply(z));
_have_gyro_sample = true;
_last_gyro_timestamp = now;
}
// give back i2c semaphore
i2c_sem->give();
}
#endif // CONFIG_HAL_BOARD
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