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there is a problem. i cant send data continuously.
Dependencies: EthernetNetIf mbed HMC6352 ITG3200 ADXL345 IMUfilter
Diff: IMUTICKER/IMUTICKER.h
- Revision:
- 0:711905e937b9
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/IMUTICKER/IMUTICKER.h Sun Jul 24 19:49:51 2011 +0000 @@ -0,0 +1,277 @@ +/** + * IMU filter example. + * + * Calculate the roll, pitch and yaw angles. + */ +#include "IMUfilter.h" +#include "ADXL345.h" +#include "ITG3200.h" + +//Gravity at Earth's surface in m/s/s +#define g0 9.812865328 +//Number of samples to average. +#define SAMPLES 4 +//Number of samples to be averaged for a null bias calculation +//during calibration. +#define CALIBRATION_SAMPLES 128 +//Convert from radians to degrees. +#define toDegrees(x) (x * 57.2957795) +//Convert from degrees to radians. +#define toRadians(x) (x * 0.01745329252) +//ITG-3200 sensitivity is 14.375 LSB/(degrees/sec). +#define GYROSCOPE_GAIN (1 / 14.375) +//Full scale resolution on the ADXL345 is 4mg/LSB. +#define ACCELEROMETER_GAIN (0.004 * g0) +//Sampling gyroscope at 200Hz. +#define GYRO_RATE 0.005 +//Sampling accelerometer at 200Hz. +#define ACC_RATE 0.005 +//Updating filter at 40Hz. +#define FILTER_RATE 0.1 + +Serial pc(USBTX, USBRX); +//At rest the gyroscope is centred around 0 and goes between about +//-5 and 5 counts. As 1 degrees/sec is ~15 LSB, error is roughly +//5/15 = 0.3 degrees/sec. +IMUfilter imuFilter(FILTER_RATE, 0.3); +ADXL345 accelerometer(p5, p6, p7, p8); +ITG3200 gyroscope(p9, p10); +Ticker accelerometerTicker; +Ticker gyroscopeTicker; +Ticker filterTicker; + +//Offsets for the gyroscope. +//The readings we take when the gyroscope is stationary won't be 0, so we'll +//average a set of readings we do get when the gyroscope is stationary and +//take those away from subsequent readings to ensure the gyroscope is offset +//or "biased" to 0. +double w_xBias; +double w_yBias; +double w_zBias; + +//Offsets for the accelerometer. +//Same as with the gyroscope. +double a_xBias; +double a_yBias; +double a_zBias; + +//Accumulators used for oversampling and then averaging. +volatile double a_xAccumulator = 0; +volatile double a_yAccumulator = 0; +volatile double a_zAccumulator = 0; +volatile double w_xAccumulator = 0; +volatile double w_yAccumulator = 0; +volatile double w_zAccumulator = 0; + +//Accelerometer and gyroscope readings for x, y, z axes. +volatile double a_x; +volatile double a_y; +volatile double a_z; +volatile double w_x; +volatile double w_y; +volatile double w_z; + +//Buffer for accelerometer readings. +int readings[3]; +//Number of accelerometer samples we're on. +int accelerometerSamples = 0; +//Number of gyroscope samples we're on. +int gyroscopeSamples = 0; + +/** + * Prototypes + */ +//Set up the ADXL345 appropriately. +void initializeAcceleromter(void); +//Calculate the null bias. +void calibrateAccelerometer(void); +//Take a set of samples and average them. +void sampleAccelerometer(void); +//Set up the ITG3200 appropriately. +void initializeGyroscope(void); +//Calculate the null bias. +void calibrateGyroscope(void); +//Take a set of samples and average them. +void sampleGyroscope(void); +//Update the filter and calculate the Euler angles. +void filter(void); + +void initializeAccelerometer(void) { + + //Go into standby mode to configure the device. + accelerometer.setPowerControl(0x00); + //Full resolution, +/-16g, 4mg/LSB. + accelerometer.setDataFormatControl(0x0B); + //200Hz data rate. + accelerometer.setDataRate(ADXL345_200HZ); + //Measurement mode. + accelerometer.setPowerControl(0x08); + //See http://www.analog.com/static/imported-files/application_notes/AN-1077.pdf + wait_ms(22); + +} + +void sampleAccelerometer(void) { + + //Have we taken enough samples? + if (accelerometerSamples == SAMPLES) { + + //Average the samples, remove the bias, and calculate the acceleration + //in m/s/s. + a_x = ((a_xAccumulator / SAMPLES) - a_xBias) * ACCELEROMETER_GAIN; + a_y = ((a_yAccumulator / SAMPLES) - a_yBias) * ACCELEROMETER_GAIN; + a_z = ((a_zAccumulator / SAMPLES) - a_zBias) * ACCELEROMETER_GAIN; + + a_xAccumulator = 0; + a_yAccumulator = 0; + a_zAccumulator = 0; + accelerometerSamples = 0; + + } else { + //Take another sample. + accelerometer.getOutput(readings); + + a_xAccumulator += (int16_t) readings[0]; + a_yAccumulator += (int16_t) readings[1]; + a_zAccumulator += (int16_t) readings[2]; + + accelerometerSamples++; + + } + +} + +void calibrateAccelerometer(void) { + + a_xAccumulator = 0; + a_yAccumulator = 0; + a_zAccumulator = 0; + + //Take a number of readings and average them + //to calculate the zero g offset. + for (int i = 0; i < CALIBRATION_SAMPLES; i++) { + + accelerometer.getOutput(readings); + + a_xAccumulator += (int16_t) readings[0]; + a_yAccumulator += (int16_t) readings[1]; + a_zAccumulator += (int16_t) readings[2]; + + wait(ACC_RATE); + + } + + a_xAccumulator /= CALIBRATION_SAMPLES; + a_yAccumulator /= CALIBRATION_SAMPLES; + a_zAccumulator /= CALIBRATION_SAMPLES; + + //At 4mg/LSB, 250 LSBs is 1g. + a_xBias = a_xAccumulator; + a_yBias = a_yAccumulator; + a_zBias = (a_zAccumulator - 250); + + a_xAccumulator = 0; + a_yAccumulator = 0; + a_zAccumulator = 0; + +} + +void initializeGyroscope(void) { + + //Low pass filter bandwidth of 42Hz. + gyroscope.setLpBandwidth(LPFBW_42HZ); + //Internal sample rate of 200Hz. (1kHz / 5). + gyroscope.setSampleRateDivider(4); + +} + +void calibrateGyroscope(void) { + + w_xAccumulator = 0; + w_yAccumulator = 0; + w_zAccumulator = 0; + + //Take a number of readings and average them + //to calculate the gyroscope bias offset. + for (int i = 0; i < CALIBRATION_SAMPLES; i++) { + + w_xAccumulator += gyroscope.getGyroX(); + w_yAccumulator += gyroscope.getGyroY(); + w_zAccumulator += gyroscope.getGyroZ(); + wait(GYRO_RATE); + + } + + //Average the samples. + w_xAccumulator /= CALIBRATION_SAMPLES; + w_yAccumulator /= CALIBRATION_SAMPLES; + w_zAccumulator /= CALIBRATION_SAMPLES; + + w_xBias = w_xAccumulator; + w_yBias = w_yAccumulator; + w_zBias = w_zAccumulator; + + w_xAccumulator = 0; + w_yAccumulator = 0; + w_zAccumulator = 0; + +} + +void sampleGyroscope(void) { + + //Have we taken enough samples? + if (gyroscopeSamples == SAMPLES) { + + //Average the samples, remove the bias, and calculate the angular + //velocity in rad/s. + w_x = toRadians(((w_xAccumulator / SAMPLES) - w_xBias) * GYROSCOPE_GAIN); + w_y = toRadians(((w_yAccumulator / SAMPLES) - w_yBias) * GYROSCOPE_GAIN); + w_z = toRadians(((w_zAccumulator / SAMPLES) - w_zBias) * GYROSCOPE_GAIN); + + w_xAccumulator = 0; + w_yAccumulator = 0; + w_zAccumulator = 0; + gyroscopeSamples = 0; + + } else { + //Take another sample. + w_xAccumulator += gyroscope.getGyroX(); + w_yAccumulator += gyroscope.getGyroY(); + w_zAccumulator += gyroscope.getGyroZ(); + + gyroscopeSamples++; + + } + +} + +void filter(void) { + + //Update the filter variables. + imuFilter.updateFilter(w_y, w_x, w_z, a_y, a_x, a_z); + //Calculate the new Euler angles. + imuFilter.computeEuler(); + +} + +void start() { + + pc.printf("Starting IMU filter test...\n"); + + //Initialize inertial sensors. + initializeAccelerometer(); + calibrateAccelerometer(); + initializeGyroscope(); + calibrateGyroscope(); + + + //Set up timers. + //Accelerometer data rate is 200Hz, so we'll sample at this speed. + accelerometerTicker.attach(&sampleAccelerometer, 0.005); + //Gyroscope data rate is 200Hz, so we'll sample at this speed. + gyroscopeTicker.attach(&sampleGyroscope, 0.005); + //Update the filter variables at the correct rate. + filterTicker.attach(&filter, FILTER_RATE); + + +}