File content as of revision 1:e9dd53326ba1:

/**********************************************************************
* Copyright (C) 2016 Maxim Integrated Products, Inc., All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL MAXIM INTEGRATED BE LIABLE FOR ANY CLAIM, DAMAGES
* OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*
* Except as contained in this notice, the name of Maxim Integrated
* Products, Inc. shall not be used except as stated in the Maxim Integrated
* Products, Inc. Branding Policy.
*
* The mere transfer of this software does not imply any licenses
* of trade secrets, proprietary technology, copyrights, patents,
* trademarks, maskwork rights, or any other form of intellectual
* property whatsoever. Maxim Integrated Products, Inc. retains all
* ownership rights.
**********************************************************************/


/*References
*
* Circuit Cellar Issue 316 November 2016
* BalanceBot: A Self-Balancing, Two-Wheeled Robot
*
* Reading a IMU Without Kalman: The Complementary Filter
* http://www.pieter-jan.com/node/11
*
*/


#include "mbed.h"
#include "max32630fthr.h"
#include "bmi160.h"


//Setup interrupt in from imu
InterruptIn imuIntIn(P3_6);
bool drdy = false;
void imuISR()
{
    drdy = true;
}


//Setup start/stop button
DigitalIn startStopBtn(P2_3, PullUp);
InterruptIn startStop(P2_3);
bool start = false;
void startStopISR()
{
    if(start)
    {
        start = false;
    }
    else
    {
        start = true;
    }
}


int main()
{
    MAX32630FTHR pegasus;
    pegasus.init(MAX32630FTHR::VIO_3V3);
    
    static const float MAX_PULSEWIDTH_US = 40.0F;
    static const float MIN_PULSEWIDTH_US = -40.0F;
    
    static const bool FORWARD = 0;
    static const bool REVERSE = 1;
       
    //Setup left motor(from driver seat)
    DigitalOut leftDir(P5_6, FORWARD);
    PwmOut leftPwm(P4_0);
    leftPwm.period_us(40);
    leftPwm.pulsewidth_us(0);
    
    //Make sure P4_2 and P4_3 are Hi-Z
    DigitalIn p42_hiZ(P4_2, PullNone);
    DigitalIn p43_hiZ(P4_3, PullNone);
    
    //Setup right motor(from driver seat)
    DigitalOut rightDir(P5_4, FORWARD);
    PwmOut rightPwm(P5_5);
    rightPwm.period_us(40);
    rightPwm.pulsewidth_us(0);
    
    //Turn off RGB LEDs
    DigitalOut rLED(LED1, LED_OFF);
    DigitalOut gLED(LED2, LED_OFF);
    DigitalOut bLED(LED3, LED_OFF);
    
    //Setup I2C bus for IMU
    I2C i2cBus(P5_7, P6_0);
    i2cBus.frequency(400000);
    
    //Get IMU instance and configure it
    BMI160_I2C imu(i2cBus, BMI160_I2C::I2C_ADRS_SDO_LO);
    
    uint32_t failures = 0;
    
    BMI160::AccConfig accConfig;
    BMI160::AccConfig accConfigRead;
    accConfig.range = BMI160::SENS_2G;
    accConfig.us = BMI160::ACC_US_OFF;
    accConfig.bwp = BMI160::ACC_BWP_2;
    accConfig.odr = BMI160::ACC_ODR_12;
    if(imu.setSensorConfig(accConfig) == BMI160::RTN_NO_ERROR)
    {
        if(imu.getSensorConfig(accConfigRead) == BMI160::RTN_NO_ERROR)
        {
            if((accConfig.range != accConfigRead.range) ||
                    (accConfig.us != accConfigRead.us) ||
                    (accConfig.bwp != accConfigRead.bwp) ||
                    (accConfig.odr != accConfigRead.odr)) 
            {
                printf("ACC read data desn't equal set data\n\n");
                printf("ACC Set Range = %d\n", accConfig.range);
                printf("ACC Set UnderSampling = %d\n", accConfig.us);
                printf("ACC Set BandWidthParam = %d\n", accConfig.bwp);
                printf("ACC Set OutputDataRate = %d\n\n", accConfig.odr);
                printf("ACC Read Range = %d\n", accConfigRead.range);
                printf("ACC Read UnderSampling = %d\n", accConfigRead.us);
                printf("ACC Read BandWidthParam = %d\n", accConfigRead.bwp);
                printf("ACC Read OutputDataRate = %d\n\n", accConfigRead.odr);
                failures++;
            }
             
        }
        else
        {
             printf("Failed to read back accelerometer configuration\n");
             failures++;
        }
    }
    else
    {
        printf("Failed to set accelerometer configuration\n");
        failures++;
    }
    
    BMI160::GyroConfig gyroConfig;
    BMI160::GyroConfig gyroConfigRead;
    gyroConfig.range = BMI160::DPS_2000;
    gyroConfig.bwp = BMI160::GYRO_BWP_2;
    gyroConfig.odr = BMI160::GYRO_ODR_12;
    if(imu.setSensorConfig(gyroConfig) == BMI160::RTN_NO_ERROR)
    {
        if(imu.getSensorConfig(gyroConfigRead) == BMI160::RTN_NO_ERROR)
        {
            if((gyroConfig.range != gyroConfigRead.range) ||
                    (gyroConfig.bwp != gyroConfigRead.bwp) ||
                    (gyroConfig.odr != gyroConfigRead.odr)) 
            {
                printf("GYRO read data desn't equal set data\n\n");
                printf("GYRO Set Range = %d\n", gyroConfig.range);
                printf("GYRO Set BandWidthParam = %d\n", gyroConfig.bwp);
                printf("GYRO Set OutputDataRate = %d\n\n", gyroConfig.odr);
                printf("GYRO Read Range = %d\n", gyroConfigRead.range);
                printf("GYRO Read BandWidthParam = %d\n", gyroConfigRead.bwp);
                printf("GYRO Read OutputDataRate = %d\n\n", gyroConfigRead.odr);
                failures++;
            }
            
        } 
        else
        {
            printf("Failed to read back gyroscope configuration\n");
            failures++;
        }
    }
    else
    {
        printf("Failed to set gyroscope configuration\n");
        failures++;
    }
    
    //Power up sensors in normal mode
    if(imu.setSensorPowerMode(BMI160::GYRO, BMI160::NORMAL) != BMI160::RTN_NO_ERROR)
    {
        printf("Failed to set gyroscope power mode\n");
        failures++;
    }
    
    wait(0.1);
    
    if(imu.setSensorPowerMode(BMI160::ACC, BMI160::NORMAL) != BMI160::RTN_NO_ERROR)
    {
        printf("Failed to set accelerometer power mode\n");
        failures++;
    }
    
    if(failures == 0)
    {
        printf("ACC Range = %d\n", accConfig.range);
        printf("ACC UnderSampling = %d\n", accConfig.us);
        printf("ACC BandWidthParam = %d\n", accConfig.bwp);
        printf("ACC OutputDataRate = %d\n\n", accConfig.odr);
        printf("GYRO Range = %d\n", gyroConfig.range);
        printf("GYRO BandWidthParam = %d\n", gyroConfig.bwp);
        printf("GYRO OutputDataRate = %d\n\n", gyroConfig.odr);
        wait(1.0);
        
        //Sensor data vars
        BMI160::SensorData accData;
        BMI160::SensorData gyroData;
        BMI160::SensorTime sensorTime;
        
        //Complementary Filter vars, filter weight K
        static const float K = 0.9993F;
        float thetaGyro = 0.0F;
        float thetaAcc = 0.0F;
        float pitch = 0.0F;
        
        //PID coefficients
        static const float DT = 0.000625F;
        static const float KP = 4.25F;
        static const float KI = (8.0F * DT);
        static const float KD = (0.04F / DT);
        float setPoint = 0.0F;
        
        //Control loop vars
        float currentError, previousError;
        float integral = 0.0F;
        float derivative = 0.0F;
        float pulseWidth;
        
        //Enable data ready interrupt from imu for constant loop timming
        imu.writeRegister(BMI160::INT_EN_1, 0x10); 
        //Active High PushPull output on INT1
        imu.writeRegister(BMI160::INT_OUT_CTRL, 0x0A); 
        //Map data ready interrupt to INT1
        imu.writeRegister(BMI160::INT_MAP_1, 0x80); 
        //Tie INT1 to callback fx
        imuIntIn.rise(&imuISR);
        
        //Tie SW2 to callback fx
        startStop.fall(&startStopISR);
        
        //control loop timming indicator
        DigitalOut loopPulse(P5_3, 0);
        
        //Count for averaging setPoint offset, 2 seconds of data
        uint32_t offsetCount = 0;
        
        while(1)
        {
            rLED = LED_ON;
            gLED = LED_ON;
            pitch = 0.0F;
            setPoint = 0.0F;
            rightPwm.pulsewidth_us(0);
            leftPwm.pulsewidth_us(0);
            start = false;
            drdy = false;
            
            while(offsetCount < 3200)
            {
                if(drdy)
                {
                    //Clear data ready flag
                    drdy = false;
                    
                    //Read feedback sensors
                    imu.getGyroAccXYZandSensorTime(accData, gyroData, sensorTime, accConfig.range, gyroConfig.range);
                    
                    //Feedback Block, Complementary filter
                    //Prediction estimate
                    thetaGyro = (pitch + (gyroData.xAxis.scaled * DT));
                    //Measurement estimate
                    thetaAcc = ((180.0F/3.14F) * atan(accData.yAxis.scaled/accData.zAxis.scaled));
                    //Feedback, Pitch estimate in degrees
                    pitch = ((K * thetaGyro) + ((1.0F - K) * thetaAcc));
                    
                    //Accumalate pitch measurements
                    setPoint += pitch;
                    offsetCount++;
                }
            }
            
            //Clear count for next time
            offsetCount = 0;
            
            //Average measurements
            setPoint = setPoint/3200.0F;
            
            printf("setPoint = %5.2f\n\n", setPoint);
            
            while(!start)
            {
                rLED = LED_ON;
                gLED = LED_ON;
                wait(0.25);
                rLED = LED_OFF;
                gLED = LED_OFF;
                wait(0.25);
            }
            
            while(start && (pitch > -30.0F) && (pitch < 30.0F))
            {
                rLED = LED_OFF;
                gLED = LED_ON;
                if(drdy)
                {
                    //Start, following takes ~456us on MAX32630FTHR with 400KHz I2C bus
                    //At 1600Hz ODR, ~73% of loop time is active doing something
                    loopPulse = !loopPulse;
                    
                    //Clear data ready flag
                    drdy = false;
                    
                    //Read feedback sensors
                    imu.getGyroAccXYZandSensorTime(accData, gyroData, sensorTime, accConfig.range, gyroConfig.range);
                    
                    //Feedback Block, Complementary filter
                    //Prediction estimate
                    thetaGyro = (pitch + (gyroData.xAxis.scaled * DT));
                    //Measurement estimate
                    thetaAcc = ((180.0F/3.14F) * atan(accData.yAxis.scaled/accData.zAxis.scaled));
                    //Feedback, Pitch estimate in degrees
                    pitch = ((K * thetaGyro) + ((1.0F - K) * thetaAcc));
                    
                    //PID Block
                    //Error signal
                    currentError = (setPoint - pitch);
                    
                    //Integral term, dt is included in KI
                    //If statement addresses integral windup
                    if(currentError == 0.0F)
                    {
                        integral = 0.0F;
                    }
                    else if(((currentError < 0.0F) && (previousError > 0.0F)) || 
                           ((currentError > 0.0F) && (previousError < 0.0F)))
                    {
                        integral = 0.0F;
                    }
                    else
                    {
                        integral = (integral + currentError);
                    }
                    
                    //Derivative term, dt is included in KD
                    derivative = (currentError - previousError);
                    
                    //Set right/left pulsewidth
                    //Just balance for now, so both left/right are the same
                    pulseWidth = ((KP * currentError) + (KI * integral) + (KD * derivative));
                    
                    //printf("Pulsewidth = %f\n\n", pulseWidth);
                    
                    //Clamp to maximum duty cycle and check for forward/reverse 
                    //based on sign of error signal (negation of pitch since setPoint = 0)
                    if(pulseWidth > MAX_PULSEWIDTH_US)
                    {
                        rightDir = FORWARD;
                        leftDir = FORWARD;
                        rightPwm.pulsewidth_us(40);
                        leftPwm.pulsewidth_us(40);
                    }
                    else if(pulseWidth < MIN_PULSEWIDTH_US)
                    {
                        rightDir = REVERSE;
                        leftDir = REVERSE;
                        rightPwm.pulsewidth_us(40);
                        leftPwm.pulsewidth_us(40);
                    }
                    else
                    {
                        if(pulseWidth < 0.0F)
                        {
                            rightDir = REVERSE;
                            leftDir = REVERSE;
                            pulseWidth = (1 - pulseWidth);
                            rightPwm.pulsewidth_us(static_cast<uint32_t>(pulseWidth));
                            leftPwm.pulsewidth_us(static_cast<uint32_t>(pulseWidth));
                        }
                        else
                        {
                            rightDir = FORWARD;
                            leftDir = FORWARD;
                            rightPwm.pulsewidth_us(static_cast<uint32_t>(pulseWidth));
                            leftPwm.pulsewidth_us(static_cast<uint32_t>(pulseWidth));
                        }
                    }
                    
                    //save current error for next loop
                    previousError = currentError;
                    
                    //Stop
                    loopPulse = !loopPulse;
                }
            }
        }
    }
    else
    {
        while(1)
        {
            rLED = !rLED;
            wait(0.25);
        }
    }
}