/************************************************************************* * Freematics MPU6050 helper class * Distributed under BSD license * Visit http://freematics.com for more information * (C)2016-2018 Stanley Huang *************************************************************************/ #include #include #include "FreematicsBase.h" #include "FreematicsMEMS.h" // Implementation of Sebastian Madgwick's "...efficient orientation filter for... inertial/magnetic sensor arrays" // (see http://www.x-io.co.uk/category/open-source/ for examples and more details) // which fuses acceleration, rotation rate, and magnetic moments to produce a quaternion-based estimate of absolute // device orientation void CQuaterion::MadgwickQuaternionUpdate(float ax, float ay, float az, float gx, float gy, float gz, float mx, float my, float mz) { uint32_t now = millis(); deltat = ((float)(now - lastUpdate)/1000.0f); // set integration time by time elapsed since last filter update lastUpdate = now; float q1 = q[0], q2 = q[1], q3 = q[2], q4 = q[3]; // short name local variable for readability float norm; float hx, hy, _2bx, _2bz; float s1, s2, s3, s4; float qDot1, qDot2, qDot3, qDot4; // Auxiliary variables to avoid repeated arithmetic float _2q1mx; float _2q1my; float _2q1mz; float _2q2mx; float _4bx; float _4bz; float _2q1 = 2.0f * q1; float _2q2 = 2.0f * q2; float _2q3 = 2.0f * q3; float _2q4 = 2.0f * q4; float _2q1q3 = 2.0f * q1 * q3; float _2q3q4 = 2.0f * q3 * q4; float q1q1 = q1 * q1; float q1q2 = q1 * q2; float q1q3 = q1 * q3; float q1q4 = q1 * q4; float q2q2 = q2 * q2; float q2q3 = q2 * q3; float q2q4 = q2 * q4; float q3q3 = q3 * q3; float q3q4 = q3 * q4; float q4q4 = q4 * q4; // Normalise accelerometer measurement norm = sqrtf(ax * ax + ay * ay + az * az); if (norm == 0.0f) return; // handle NaN norm = 1.0f/norm; ax *= norm; ay *= norm; az *= norm; // Normalise magnetometer measurement norm = sqrtf(mx * mx + my * my + mz * mz); if (norm == 0.0f) return; // handle NaN norm = 1.0f/norm; mx *= norm; my *= norm; mz *= norm; // Reference direction of Earth's magnetic field _2q1mx = 2.0f * q1 * mx; _2q1my = 2.0f * q1 * my; _2q1mz = 2.0f * q1 * mz; _2q2mx = 2.0f * q2 * mx; hx = mx * q1q1 - _2q1my * q4 + _2q1mz * q3 + mx * q2q2 + _2q2 * my * q3 + _2q2 * mz * q4 - mx * q3q3 - mx * q4q4; hy = _2q1mx * q4 + my * q1q1 - _2q1mz * q2 + _2q2mx * q3 - my * q2q2 + my * q3q3 + _2q3 * mz * q4 - my * q4q4; _2bx = sqrtf(hx * hx + hy * hy); _2bz = -_2q1mx * q3 + _2q1my * q2 + mz * q1q1 + _2q2mx * q4 - mz * q2q2 + _2q3 * my * q4 - mz * q3q3 + mz * q4q4; _4bx = 2.0f * _2bx; _4bz = 2.0f * _2bz; // Gradient decent algorithm corrective step s1 = -_2q3 * (2.0f * q2q4 - _2q1q3 - ax) + _2q2 * (2.0f * q1q2 + _2q3q4 - ay) - _2bz * q3 * (_2bx * (0.5f - q3q3 - q4q4) + _2bz * (q2q4 - q1q3) - mx) + (-_2bx * q4 + _2bz * q2) * (_2bx * (q2q3 - q1q4) + _2bz * (q1q2 + q3q4) - my) + _2bx * q3 * (_2bx * (q1q3 + q2q4) + _2bz * (0.5f - q2q2 - q3q3) - mz); s2 = _2q4 * (2.0f * q2q4 - _2q1q3 - ax) + _2q1 * (2.0f * q1q2 + _2q3q4 - ay) - 4.0f * q2 * (1.0f - 2.0f * q2q2 - 2.0f * q3q3 - az) + _2bz * q4 * (_2bx * (0.5f - q3q3 - q4q4) + _2bz * (q2q4 - q1q3) - mx) + (_2bx * q3 + _2bz * q1) * (_2bx * (q2q3 - q1q4) + _2bz * (q1q2 + q3q4) - my) + (_2bx * q4 - _4bz * q2) * (_2bx * (q1q3 + q2q4) + _2bz * (0.5f - q2q2 - q3q3) - mz); s3 = -_2q1 * (2.0f * q2q4 - _2q1q3 - ax) + _2q4 * (2.0f * q1q2 + _2q3q4 - ay) - 4.0f * q3 * (1.0f - 2.0f * q2q2 - 2.0f * q3q3 - az) + (-_4bx * q3 - _2bz * q1) * (_2bx * (0.5f - q3q3 - q4q4) + _2bz * (q2q4 - q1q3) - mx) + (_2bx * q2 + _2bz * q4) * (_2bx * (q2q3 - q1q4) + _2bz * (q1q2 + q3q4) - my) + (_2bx * q1 - _4bz * q3) * (_2bx * (q1q3 + q2q4) + _2bz * (0.5f - q2q2 - q3q3) - mz); s4 = _2q2 * (2.0f * q2q4 - _2q1q3 - ax) + _2q3 * (2.0f * q1q2 + _2q3q4 - ay) + (-_4bx * q4 + _2bz * q2) * (_2bx * (0.5f - q3q3 - q4q4) + _2bz * (q2q4 - q1q3) - mx) + (-_2bx * q1 + _2bz * q3) * (_2bx * (q2q3 - q1q4) + _2bz * (q1q2 + q3q4) - my) + _2bx * q2 * (_2bx * (q1q3 + q2q4) + _2bz * (0.5f - q2q2 - q3q3) - mz); norm = sqrtf(s1 * s1 + s2 * s2 + s3 * s3 + s4 * s4); // normalise step magnitude norm = 1.0f/norm; s1 *= norm; s2 *= norm; s3 *= norm; s4 *= norm; // Compute rate of change of quaternion qDot1 = 0.5f * (-q2 * gx - q3 * gy - q4 * gz) - beta * s1; qDot2 = 0.5f * (q1 * gx + q3 * gz - q4 * gy) - beta * s2; qDot3 = 0.5f * (q1 * gy - q2 * gz + q4 * gx) - beta * s3; qDot4 = 0.5f * (q1 * gz + q2 * gy - q3 * gx) - beta * s4; // Integrate to yield quaternion q1 += qDot1 * deltat; q2 += qDot2 * deltat; q3 += qDot3 * deltat; q4 += qDot4 * deltat; norm = sqrtf(q1 * q1 + q2 * q2 + q3 * q3 + q4 * q4); // normalise quaternion norm = 1.0f/norm; q[0] = q1 * norm; q[1] = q2 * norm; q[2] = q3 * norm; q[3] = q4 * norm; } void CQuaterion::getOrientation(ORIENTATION* ori) { ori->yaw = atan2(2.0f * (q[1] * q[2] + q[0] * q[3]), q[0] * q[0] + q[1] * q[1] - q[2] * q[2] - q[3] * q[3]) * 180.0f / PI; ori->pitch = -asin(2.0f * (q[1] * q[3] - q[0] * q[2])) * 180.0f / PI; ori->roll = atan2(2.0f * (q[0] * q[1] + q[2] * q[3]), q[0] * q[0] - q[1] * q[1] - q[2] * q[2] + q[3] * q[3]) * 180.0f / PI; } //============================================================================== //====== Set of useful function to access acceleration. gyroscope, magnetometer, //====== and temperature data //============================================================================== void MPU9250_ACC::readAccelData(int16_t * destination) { uint8_t rawData[6]; // x/y/z accel register data stored here readBytes(ACCEL_XOUT_H, 6, &rawData[0]); // Read the six raw data registers into data array destination[0] = ((int16_t)rawData[0] << 8) | rawData[1] ; // Turn the MSB and LSB into a signed 16-bit value destination[1] = ((int16_t)rawData[2] << 8) | rawData[3] ; destination[2] = ((int16_t)rawData[4] << 8) | rawData[5] ; } void MPU9250_9DOF::readGyroData(int16_t * destination) { uint8_t rawData[6]; // x/y/z gyro register data stored here readBytes(GYRO_XOUT_H, 6, &rawData[0]); // Read the six raw data registers sequentially into data array destination[0] = ((int16_t)rawData[0] << 8) | rawData[1] ; // Turn the MSB and LSB into a signed 16-bit value destination[1] = ((int16_t)rawData[2] << 8) | rawData[3] ; destination[2] = ((int16_t)rawData[4] << 8) | rawData[5] ; } void MPU9250_9DOF::readMagData(int16_t * destination) { if(readByteAK(AK8963_ST1) & 0x01) { // wait for magnetometer data ready bit to be set uint8_t rawData[7]; // x/y/z gyro register data, ST2 register stored here, must read ST2 at end of data acquisition readBytesAK(AK8963_XOUT_L, 7, &rawData[0]); // Read the six raw data and ST2 registers sequentially into data array uint8_t c = rawData[6]; // End data read by reading ST2 register if(!(c & 0x08)) { // Check if magnetic sensor overflow set, if not then report data destination[0] = ((int16_t)rawData[1] << 8) | rawData[0] ; // Turn the MSB and LSB into a signed 16-bit value destination[1] = ((int16_t)rawData[3] << 8) | rawData[2] ; // Data stored as little Endian destination[2] = ((int16_t)rawData[5] << 8) | rawData[4] ; } } } int16_t MPU9250_ACC::readTempData() { uint8_t rawData[2]; // x/y/z gyro register data stored here readBytes(TEMP_OUT_H, 2, &rawData[0]); // Read the two raw data registers sequentially into data array return ((int16_t)rawData[0] << 8) | rawData[1]; // Turn the MSB and LSB into a 16-bit value } bool MPU9250_9DOF::initAK8963(float * destination) { if (readByteAK(WHO_AM_I_AK8963) != 0x48) { return false; } // First extract the factory calibration for each magnetometer axis uint8_t rawData[3]; // x/y/z gyro calibration data stored here writeByteAK(AK8963_CNTL, 0x00); // Power down magnetometer delay(10); writeByteAK(AK8963_CNTL, 0x0F); // Enter Fuse ROM access mode delay(10); // Read the x-, y-, and z-axis calibration values /* if (!readBytesAK(AK8963_ASAX, 3, &rawData[0], 3000)) { return false; } */ rawData[0] = readByteAK(AK8963_ASAX); rawData[1] = readByteAK(AK8963_ASAX); rawData[2] = readByteAK(AK8963_ASAX); destination[0] = (float)(rawData[0] - 128)/256. + 1.; // Return x-axis sensitivity adjustment values, etc. destination[1] = (float)(rawData[1] - 128)/256. + 1.; destination[2] = (float)(rawData[2] - 128)/256. + 1.; writeByte(AK8963_CNTL, 0x00); // Power down magnetometer delay(10); // Configure the magnetometer for continuous read and highest resolution // set Mscale bit 4 to 1 (0) to enable 16 (14) bit resolution in CNTL register, // and enable continuous mode data acquisition Mmode (bits [3:0]), 0010 for 8 Hz and 0110 for 100 Hz sample rates writeByte(AK8963_CNTL, MFS_16BITS << 4 | Mmode); // Set magnetometer data resolution and sample ODR delay(10); return true; } // Function which accumulates gyro and accelerometer data after device // initialization. It calculates the average of the at-rest readings and then // loads the resulting offsets into accelerometer and gyro bias registers. void MPU9250_9DOF::calibrateMPU9250(float * gyroBias, float * accelBias) { uint8_t data[12]; // data array to hold accelerometer and gyro x, y, z, data uint16_t ii, packet_count, fifo_count; int32_t gyro_bias[3] = {0, 0, 0}, accel_bias[3] = {0, 0, 0}; // reset device // Write a one to bit 7 reset bit; toggle reset device writeByte(PWR_MGMT_1, 0x80); delay(100); // get stable time source; Auto select clock source to be PLL gyroscope // reference if ready else use the internal oscillator, bits 2:0 = 001 writeByte(PWR_MGMT_1, 0x01); writeByte(PWR_MGMT_2, 0x00); delay(200); // Configure device for bias calculation writeByte(INT_ENABLE, 0x00); // Disable all interrupts writeByte(FIFO_EN, 0x00); // Disable FIFO writeByte(PWR_MGMT_1, 0x00); // Turn on internal clock source writeByte(I2C_MST_CTRL, 0x00); // Disable master writeByte(USER_CTRL, 0x00); // Disable FIFO and I2C master modes writeByte(USER_CTRL, 0x2C); // Reset FIFO and DMP delay(15); // Configure MPU6050 gyro and accelerometer for bias calculation writeByte(CONFIG, 0x01); // Set low-pass filter to 188 Hz writeByte(SMPLRT_DIV, 0x00); // Set sample rate to 1 kHz writeByte(GYRO_CONFIG, 0x00); // Set gyro full-scale to 250 degrees per second, maximum sensitivity writeByte(ACCEL_CONFIG, 0x00); // Set accelerometer full-scale to 2 g, maximum sensitivity uint16_t gyrosensitivity = 131; // = 131 LSB/degrees/sec uint16_t accelsensitivity = 16384; // = 16384 LSB/g // Configure FIFO to capture accelerometer and gyro data for bias calculation writeByte(USER_CTRL, 0x40); // Enable FIFO writeByte(FIFO_EN, 0x78); // Enable gyro and accelerometer sensors for FIFO (max size 512 bytes in MPU-9150) delay(40); // accumulate 40 samples in 40 milliseconds = 480 bytes // At end of sample accumulation, turn off FIFO sensor read writeByte(FIFO_EN, 0x00); // Disable gyro and accelerometer sensors for FIFO readBytes(FIFO_COUNTH, 2, &data[0]); // read FIFO sample count fifo_count = ((uint16_t)data[0] << 8) | data[1]; packet_count = fifo_count/12;// How many sets of full gyro and accelerometer data for averaging for (ii = 0; ii < packet_count; ii++) { int16_t accel_temp[3] = {0, 0, 0}, gyro_temp[3] = {0, 0, 0}; readBytes(FIFO_R_W, 12, &data[0]); // read data for averaging accel_temp[0] = (int16_t) (((int16_t)data[0] << 8) | data[1] ); // Form signed 16-bit integer for each sample in FIFO accel_temp[1] = (int16_t) (((int16_t)data[2] << 8) | data[3] ); accel_temp[2] = (int16_t) (((int16_t)data[4] << 8) | data[5] ); gyro_temp[0] = (int16_t) (((int16_t)data[6] << 8) | data[7] ); gyro_temp[1] = (int16_t) (((int16_t)data[8] << 8) | data[9] ); gyro_temp[2] = (int16_t) (((int16_t)data[10] << 8) | data[11]); accel_bias[0] += (int32_t) accel_temp[0]; // Sum individual signed 16-bit biases to get accumulated signed 32-bit biases accel_bias[1] += (int32_t) accel_temp[1]; accel_bias[2] += (int32_t) accel_temp[2]; gyro_bias[0] += (int32_t) gyro_temp[0]; gyro_bias[1] += (int32_t) gyro_temp[1]; gyro_bias[2] += (int32_t) gyro_temp[2]; } accel_bias[0] /= (int32_t) packet_count; // Normalize sums to get average count biases accel_bias[1] /= (int32_t) packet_count; accel_bias[2] /= (int32_t) packet_count; gyro_bias[0] /= (int32_t) packet_count; gyro_bias[1] /= (int32_t) packet_count; gyro_bias[2] /= (int32_t) packet_count; if(accel_bias[2] > 0L) {accel_bias[2] -= (int32_t) accelsensitivity;} // Remove gravity from the z-axis accelerometer bias calculation else {accel_bias[2] += (int32_t) accelsensitivity;} // Construct the gyro biases for push to the hardware gyro bias registers, which are reset to zero upon device startup data[0] = (-gyro_bias[0]/4 >> 8) & 0xFF; // Divide by 4 to get 32.9 LSB per deg/s to conform to expected bias input format data[1] = (-gyro_bias[0]/4) & 0xFF; // Biases are additive, so change sign on calculated average gyro biases data[2] = (-gyro_bias[1]/4 >> 8) & 0xFF; data[3] = (-gyro_bias[1]/4) & 0xFF; data[4] = (-gyro_bias[2]/4 >> 8) & 0xFF; data[5] = (-gyro_bias[2]/4) & 0xFF; // Push gyro biases to hardware registers writeByte(XG_OFFSET_H, data[0]); writeByte(XG_OFFSET_L, data[1]); writeByte(YG_OFFSET_H, data[2]); writeByte(YG_OFFSET_L, data[3]); writeByte(ZG_OFFSET_H, data[4]); writeByte(ZG_OFFSET_L, data[5]); // Output scaled gyro biases for display in the main program gyroBias[0] = (float) gyro_bias[0]/(float) gyrosensitivity; gyroBias[1] = (float) gyro_bias[1]/(float) gyrosensitivity; gyroBias[2] = (float) gyro_bias[2]/(float) gyrosensitivity; // Construct the accelerometer biases for push to the hardware accelerometer bias registers. These registers contain // factory trim values which must be added to the calculated accelerometer biases; on boot up these registers will hold // non-zero values. In addition, bit 0 of the lower byte must be preserved since it is used for temperature // compensation calculations. Accelerometer bias registers expect bias input as 2048 LSB per g, so that // the accelerometer biases calculated above must be divided by 8. int32_t accel_bias_reg[3] = {0, 0, 0}; // A place to hold the factory accelerometer trim biases readBytes(XA_OFFSET_H, 2, &data[0]); // Read factory accelerometer trim values accel_bias_reg[0] = (int32_t) (((int16_t)data[0] << 8) | data[1]); readBytes(YA_OFFSET_H, 2, &data[0]); accel_bias_reg[1] = (int32_t) (((int16_t)data[0] << 8) | data[1]); readBytes(ZA_OFFSET_H, 2, &data[0]); accel_bias_reg[2] = (int32_t) (((int16_t)data[0] << 8) | data[1]); uint32_t mask = 1uL; // Define mask for temperature compensation bit 0 of lower byte of accelerometer bias registers uint8_t mask_bit[3] = {0, 0, 0}; // Define array to hold mask bit for each accelerometer bias axis for(ii = 0; ii < 3; ii++) { if((accel_bias_reg[ii] & mask)) mask_bit[ii] = 0x01; // If temperature compensation bit is set, record that fact in mask_bit } // Construct total accelerometer bias, including calculated average accelerometer bias from above accel_bias_reg[0] -= (accel_bias[0]/8); // Subtract calculated averaged accelerometer bias scaled to 2048 LSB/g (16 g full scale) accel_bias_reg[1] -= (accel_bias[1]/8); accel_bias_reg[2] -= (accel_bias[2]/8); data[0] = (accel_bias_reg[0] >> 8) & 0xFF; data[1] = (accel_bias_reg[0]) & 0xFF; data[1] = data[1] | mask_bit[0]; // preserve temperature compensation bit when writing back to accelerometer bias registers data[2] = (accel_bias_reg[1] >> 8) & 0xFF; data[3] = (accel_bias_reg[1]) & 0xFF; data[3] = data[3] | mask_bit[1]; // preserve temperature compensation bit when writing back to accelerometer bias registers data[4] = (accel_bias_reg[2] >> 8) & 0xFF; data[5] = (accel_bias_reg[2]) & 0xFF; data[5] = data[5] | mask_bit[2]; // preserve temperature compensation bit when writing back to accelerometer bias registers // Apparently this is not working for the acceleration biases in the MPU-9250 // Are we handling the temperature correction bit properly? // Push accelerometer biases to hardware registers writeByte(XA_OFFSET_H, data[0]); writeByte(XA_OFFSET_L, data[1]); writeByte(YA_OFFSET_H, data[2]); writeByte(YA_OFFSET_L, data[3]); writeByte(ZA_OFFSET_H, data[4]); writeByte(ZA_OFFSET_L, data[5]); // Output scaled accelerometer biases for display in the main program accelBias[0] = (float)accel_bias[0]/(float)accelsensitivity; accelBias[1] = (float)accel_bias[1]/(float)accelsensitivity; accelBias[2] = (float)accel_bias[2]/(float)accelsensitivity; } // Accelerometer and gyroscope self test; check calibration wrt factory settings void MPU9250_9DOF::MPU9250SelfTest(float * destination) // Should return percent deviation from factory trim values, +/- 14 or less deviation is a pass { uint8_t rawData[6] = {0, 0, 0, 0, 0, 0}; uint8_t selfTest[6]; int16_t gAvg[3], aAvg[3], aSTAvg[3], gSTAvg[3]; float factoryTrim[6]; uint8_t FS = 0; writeByte(SMPLRT_DIV, 0x00); // Set gyro sample rate to 1 kHz writeByte(CONFIG, 0x02); // Set gyro sample rate to 1 kHz and DLPF to 92 Hz writeByte(GYRO_CONFIG, 1<MadgwickQuaternionUpdate(acc[0], acc[1], acc[2], gyr[0]*PI/180.0f, gyr[1]*PI/180.0f, gyr[2]*PI/180.0f, mag[0], mag[1], mag[2]); quaterion->getOrientation(ori); } return true; }