File content as of revision 3:d4736e223540:

//20211018 version
#include "MTi2.h"
#include <stdio.h>
#include "mbed.h"
#include <math.h>
#include <stdlib.h>
#include "PMW3901.h"

#define GRAVITYACCELERATION 9.81f
#define pi 3.14159265358979323846f
//motor
#define maximum_volt 12.0f
#define minimum_volt 0.45f // Need to test for different loads.

#define INPUT_VOLTAGE       12.5f 
#define PWM_FREQUENCY       10.0f   // the default value we set is 20.0 (unit : kHz)
#define PWM_STOP            0.5f    //the pwm dutycycle value is from 0~1 and 0.5 can let motor stop

#define FRICTION_VOLTAGE    0.45f
#define HALL_RESOLUTION     64.0f
#define GEAR_RATIO          56.0f      
#define VOLT_CMD            8.0f    // unit(voltage)

//Common
Serial pc(USBTX,USBRX);
InterruptIn mybutton(USER_BUTTON);
Ticker main_function; //interrupt
DigitalOut led1(LED1);
DigitalOut led2(A4);
DigitalOut led3(A5);

//IMU
SPI spi_MTI(PB_15, PB_14, PB_13);//MOSI MISO SCLK
DigitalOut cs_MTI(PC_4);

//GSS
SPI spi(PC_12,PC_11,PC_10);
DigitalOut cs(PA_4);

//motor
PwmOut pwm1A(D7);
PwmOut pwm1B(D8);
PwmOut pwm2A(D11);
PwmOut pwm2B(A3);

//Common
bool button_state = false;
float dt = 0.01; // sec
//IMU
typedef union{
    uint32_t data1;
    float data2;
}imu_data;

imu_data eul[3];//euler angle
imu_data acc[3];
imu_data gry[3];
//GSS
int GSS_X = 0;
int GSS_Y = 0;

//motor
int readcount = 0;
int RX_flag2 = 0;
char getData[6] = {0,0,0,0,0,0};
short data_received[2] = {0,0};

float command = 0;
float velocityA = 0; //rpm
float velocityB = 0;
float positionA = 0;
float positionB = 0;
short EncoderPositionA;
short EncoderPositionB;
float last_voltA = 0;
float last_voltB = 0;
float errorA = 0;
float error_drA = 0;
float errorB = 0;
float error_drB = 0;
float dutycycle = PWM_STOP;
float VELOCITY_SPEED_A = 0.0;
float VELOCITY_SPEED_B = 0.0;
int pub_count = 0;

//Common
void step_command();

//IMU
void Start_read();

//GSS
void grabData(void);
//void printData(void);
void initializeSensor(void);
void writeRegister(uint8_t addr, uint8_t data);
uint8_t readRegister(uint8_t addr);
void delayus(uint32_t us);

//motor
float PD(float e, float last_e, float last_u, float P, float D);
float PDF(float e, float last_e, float last_u, float P, float D, float F);
void ReadVelocity();
void ReadPosition(float *positionA, float *positionB);
void motor_drive(float voltA, float voltB);
void InitMotor(float pwm_frequency);
void InitEncoder(void);
void control_speed();

void RX_ITR();
void init_UART();

int main(void)
{
    //pc.baud(230400);
    //pc.baud(460800);
    led2 = 1;
    led3 = 1;
    //IMU
    spi_MTI.format(8, 3);
    MTi2_Init();
    //GSS
    spi.format(8, 3);
    initializeSensor();
    //motor
    init_UART();
    InitEncoder();
    InitMotor(PWM_FREQUENCY);
    
    mybutton.fall(&step_command);
    main_function.attach_us(&Start_read,dt*1000000);
    while (1) {
    }

}

void Start_read()                      //interrupt function by TT
{
    //IMU
    ReadData();
    //GSS
    cs = 0;
    grabData();
    cs = 1;
    if(button_state == true){
        pub_count++;
//        VELOCITY_SPEED_A = -10.0f;
//        VELOCITY_SPEED_B = -10.0f;
        ReadVelocity();
        control_speed();
        if (pub_count >= 10){
            //printf("%.3f,%.3f\r\n",velocityA, velocityB);  // velocityA or velocityB
            //printf("CMD %.3f,%.3f\r\n",VELOCITY_SPEED_A, VELOCITY_SPEED_B);
            pub_count = 0;
        }
    }else{
        uint16_t dutycycleA = PWM_STOP *uint16_t(TIM1->ARR);
        uint16_t dutycycleB = PWM_STOP *uint16_t(TIM1->ARR);
        TIM1->CCR1 = dutycycleA;
        TIM1->CCR2 = dutycycleB;
        command = 0;
    }
    if (button_state == true)
    {
        
//        printf("%.4f,%.4f,%.4f,%.4f,%.4f,%.4f,%.4f,%.4f,%.4f\r\n",euler[0],euler[1],euler[2],accel_[0],accel_[1],accel_[2],omega[0],omega[1],omega[2]);
//        printf("%.4f,%.4f,%.4f,   %.4f,%.4f,%.4f,   %.4f,%.4f,%.4f,   %.4f,%.4f,%.4f\r\n",euler[0],euler[1],euler[2],   accel[0],accel[1],accel[2],  accel_[0],accel_[1],accel_[2],  accel__[0],accel__[1],accel__[2]);
//        printf("%d,%d\n\r", GSS_X, GSS_Y);
//        printf("%.3f,%.3f\r\n",velocityA, velocityB);  // velocityA or velocityB

        printf("%.3f,%.3f,%d,%d,%.4f,%.4f,%.4f\r\n",velocityA, velocityB, GSS_X, GSS_Y, accel_[0],accel_[1], omega[2]);

//        printf("%.3f,%.3f\r\n",VELOCITY_SPEED_A, VELOCITY_SPEED_B);
//        printf("%.2f,%.2f\r\n",VELOCITY_SPEED_A, VELOCITY_SPEED_B);
    }
}


void step_command(){
    led1 = !led1;
    led2 = !led2;
    led3 = !led3;
    button_state = !button_state;
}
//IMU
void SendOpcode(uint8_t Opcode)
{
//    printf("SendOpcode \r\n");
    FW[0] = spi_MTI.write(Opcode);
    
    for(uint8_t i = 0;i<3;i++){// 3 fillword ?
        FW[i+1] = spi_MTI.write(i);
    }
}

//uint8_t ReadProtInfo(){
//    len = 2;
//    cs_MTI = 0;
//    SendOpcode(ProtInfo);//send opcode
//    for(int i = 0;i<len;i++){//read data
//        buffer[i] = spi_MTI.write(0x00);
//    }
//    cs_MTI = 1;
//    if(FW[0]!=0xFA||FW[1]!=0xFF||FW[2]!=0xFF||FW[3]!=0xFF){
//        printf("Error!!\n");
//    }
//    return buffer[1];
//}

void ConfigureProt(_Bool M,_Bool N,_Bool O,_Bool P)
{
//    printf("ConfigureProt \r\n");
    uint8_t config = (M<<3) | (N<<2) | (O<<1) | (P<<0);
    cs_MTI = 0;
    SendOpcode(ConfigProt);
    spi_MTI.write(config);
    cs_MTI = 1;
}

void PipeStatus(){
//    printf("PipeStatus \r\n");
    len = 4;
    cs_MTI = 0;
    SendOpcode(PipeStat);//send opcode
    for(int i = 0;i<len;i++){//read data
        buffer[i] = spi_MTI.write(0x00);
    }
    cs_MTI = 1;
    notificationSize = buffer[0] | (buffer[1]<<8);
    measurementSize = buffer[2] | (buffer[3]<<8);
    //printf("nSize:%d\r\n",notificationSize);
    //printf("mSize:%d\r\n",measurementSize);
}

//void NotificationPipe(){
//    cs_MTI = 0;
//    SendOpcode(NotiPipe);//send opcode
//    for(int i = 0;i<notificationSize;i++){//read data
//        buffer[i] = spi_MTI.write(0x00);
//    }
//    cs_MTI = 1;
//}

void MeasurementPipe(){
//    printf("MeasurementPipe \r\n");
    cs_MTI = 0;
    SendOpcode(MeasPipe);//send opcode
    for(int i = 0;i<measurementSize;i++){//read data
        buffer[i] = spi_MTI.write(0x00);
    }
    cs_MTI = 1;
}

void ControlPipe(){
    cs_MTI = 0;
        SendOpcode(Control);//send opcode
        for(int i = 0;i<ctrl_len;i++){//read data
            buffer[i] = spi_MTI.write(ctrlBuf[i]);
        }
    cs_MTI = 1;
}

void ReadData(){
//    printf("ReadData \r\n");
    PipeStatus();
    wait_us(100);
    MeasurementPipe();
    int len1,len2,len3,data_bytes;
//    printf("Measurement FINISH \r\n");
//    printf("buffer[0] == %d \r\n",buffer[0]);
    if(buffer[0] == 0x36){
//        printf("buffer \r\n");
        if(buffer[2]== 0x20&&buffer[3]== 0x30){//Read Euler Angle
            len1 = buffer[4];
            data_bytes = len1/3;
            for(int j=0;j<3;j++){
                uint32_t temp = (buffer[5+j*data_bytes]<<24) | (buffer[6+j*data_bytes]<<16) | (buffer[7+j*data_bytes]<<8) | (buffer[8+j*data_bytes]);
                eul[j].data1 = temp;
                //euler[j] = lpf(eul[j].data2, euler[j], 13.0f);
                euler[j] = eul[j].data2;
            }
        }
        if(buffer[4+len1+1]== 0x40&&buffer[4+len1+2]== 0x20){
            len2 = buffer[4+len1+3];
            data_bytes = len2/3;
            for(int j=0;j<3;j++){
                uint32_t temp = (buffer[8+len1+j*data_bytes]<<24) | (buffer[9+len1+j*data_bytes]<<16) | (buffer[10+len1+j*data_bytes]<<8) | (buffer[11+len1+j*data_bytes]);
                acc[j].data1 = temp;
                accel[j] = lpf(acc[j].data2, accel[j], 13.0f);
            }
        }
        if(buffer[7+len1+len2+1]== 0x80&&buffer[7+len1+len2+2]==0x20){
            len3 = buffer[7+len1+len2+3];
            data_bytes = len3/3;
            for(int j=0;j<3;j++){
                uint32_t temp = (buffer[11+len1+len2+j*data_bytes]<<24) | (buffer[12+len1+len2+j*data_bytes]<<16) | (buffer[13+len1+len2+j*data_bytes]<<8) | (buffer[14+len1+len2+j*data_bytes]);
                gry[j].data1 = temp;
                omega[j] = lpf(gry[j].data2, omega[j], 13.0f);
            }
        }

    }
    eu[0] = euler[0]/180.0f*pi;
    eu[1] = euler[1]/180.0f*pi;
    eu[2] = 0; //Because euler[2] is not correct, set euler[2] = 0.
    //deal with tilt angle ; *-1 because IMU on robot is 180 degree reverse
    //Use Euler angles Z1X2Y3.
    accel_[0] = (cos(eu[2])*cos(eu[1]))*accel[0] + (cos(eu[2])*sin(eu[1])*sin(eu[0])-cos(eu[0])*sin(eu[2]))*accel[1] + (sin(eu[2])*sin(eu[0])+cos(eu[2])*cos(eu[0])*sin(eu[1]))*accel[2];
    accel_[1] = (cos(eu[1])*sin(eu[2]))*accel[0] + (cos(eu[2])*cos(eu[0])+sin(eu[2])*sin(eu[1])*sin(eu[0]))*accel[1] + (cos(eu[0])*sin(eu[2])*sin(eu[1])-cos(eu[2])*sin(eu[0]))*accel[2];
    accel_[2] = -1.0f*(sin(eu[1]))*accel[0] + (cos(eu[1])*sin(eu[0]))*accel[1] + (cos(eu[1])*cos(eu[0]))*accel[2];
    accel_[0] = accel_[0] * (-1.0f);
    accel_[1] = accel_[1] * (-1.0f);
    
//    accel__[0] = (accel[0] + sin(euler[1]/180.0f*pi) * GRAVITYACCELERATION) / cos(euler[1]/180.0f*pi) * (-1.0f);//deal with gravity * tilt angle ; *-1 because IMU on robot is 180 degree reverse
//    accel__[1] = (accel[1] - sin(euler[0]/180.0f*pi) * GRAVITYACCELERATION) / cos(euler[0]/180.0f*pi) * (-1.0f);
//    accel__[2] = accel[2];
}

void MTi2_Init(){
//    printf("Init \r\n");
    cs_MTI = 1;///???
    ConfigureProt(1,0,0,0);//Configure DRDY
}

float lpf(float input, float output_old, float frequency)
{
    float output = 0;
    output = (output_old + frequency * dt * input) / (1 + frequency * dt);
    return output;
}

//GSS

uint8_t readRegister(uint8_t addr) {
    wait_us(10);                                //tswr

    cs = 0;
    addr = addr & 0x7F;                         //Set MSB to 0 to indicate read operation

    spi.write(addr);
    
    wait_us(35);

    uint8_t data_read = spi.write(0U);
    
    wait_us(1);                             //tsclk-ncs
    cs = 1;
    wait_us(20);                            //tsclk-ncs
    return data_read;                           //Returns 8-bit data from register
}

//=========================================================================
void writeRegister(uint8_t addr, uint8_t data) {
    cs = 0;
    addr = addr | 0x80;             //Set MSB to 1 to indicate write operation

    spi.write(addr);
    
    spi.write(data);

    wait_us(25);                            //tsclk-ncs
    cs = 1;
    wait_us(1);                             //tsclk-ncs
}

//=========================================================================
void initializeSensor(void) {
    writeRegister(0x7F, 0x00);
    writeRegister(0x55, 0x01);
    writeRegister(0x50, 0x07);
    writeRegister(0x7F, 0x0E);
    writeRegister(0x43, 0x10);

    if (readRegister(0x67) & 0x40)
        writeRegister(0x48, 0x04);
    else
        writeRegister(0x48, 0x02);

    writeRegister(0x7F, 0x00);
    writeRegister(0x51, 0x7B);
    writeRegister(0x50, 0x00);
    writeRegister(0x55, 0x00);
    writeRegister(0x7F, 0x0E);

    if (readRegister(0x73) == 0x00) {
        writeRegister(0x7F, 0x00);
        writeRegister(0x61, 0xAD);
        writeRegister(0x51, 0x70);
        writeRegister(0x7F, 0x0E);

        if (readRegister(0x70) <= 28)
            writeRegister(0x70, readRegister(0x70) + 14);
        else
            writeRegister(0x70, readRegister(0x70) + 11);

        writeRegister(0x71, readRegister(0x71) * 45 / 100);
    }

    writeRegister(0x7F, 0x00);
    writeRegister(0x61, 0xAD);
    writeRegister(0x7F, 0x03);
    writeRegister(0x40, 0x00);
    writeRegister(0x7F, 0x05);
    writeRegister(0x41, 0xB3);
    writeRegister(0x43, 0xF1);
    writeRegister(0x45, 0x14);
    writeRegister(0x5B, 0x32);
    writeRegister(0x5F, 0x34);
    writeRegister(0x7B, 0x08);
    writeRegister(0x7F, 0x06);
    writeRegister(0x44, 0x1B);
    writeRegister(0x40, 0xBF);
    writeRegister(0x4E, 0x3F);
    writeRegister(0x7F, 0x06);
    writeRegister(0x44, 0x1B);
    writeRegister(0x40, 0xBF);
    writeRegister(0x4E, 0x3F);
    writeRegister(0x7F, 0x08);
    writeRegister(0x65, 0x20);
    writeRegister(0x6A, 0x18);
    writeRegister(0x7F, 0x09);
    writeRegister(0x4F, 0xAF);
    writeRegister(0x5F, 0x40);
    writeRegister(0x48, 0x80);
    writeRegister(0x49, 0x80);
    writeRegister(0x57, 0x77);
    writeRegister(0x60, 0x78);
    writeRegister(0x61, 0x78);
    writeRegister(0x62, 0x08);
    writeRegister(0x63, 0x50);
    writeRegister(0x7F, 0x0A);
    writeRegister(0x45, 0x60);
    writeRegister(0x7F, 0x00);
    writeRegister(0x4D, 0x11);
    writeRegister(0x55, 0x80);
    writeRegister(0x74, 0x21);
    writeRegister(0x75, 0x1F);
    writeRegister(0x4A, 0x78);
    writeRegister(0x4B, 0x78);
    writeRegister(0x44, 0x08);
    writeRegister(0x45, 0x50);
    writeRegister(0x64, 0xFF);
    writeRegister(0x65, 0x1F);
    writeRegister(0x7F, 0x14);
    writeRegister(0x65, 0x67);
    writeRegister(0x66, 0x08);
    writeRegister(0x63, 0x70);
    writeRegister(0x7F, 0x15);
    writeRegister(0x48, 0x48);
    writeRegister(0x7F, 0x07);
    writeRegister(0x41, 0x0D);
    writeRegister(0x43, 0x14);
    writeRegister(0x4B, 0x0E);
    writeRegister(0x45, 0x0F);
    writeRegister(0x44, 0x42);
    writeRegister(0x4C, 0x80);
    writeRegister(0x7F, 0x10);
    writeRegister(0x5B, 0x02);
    writeRegister(0x7F, 0x07);
    writeRegister(0x40, 0x41);
    writeRegister(0x70, 0x00);

    wait_ms(10);

    writeRegister(0x32, 0x44);
    writeRegister(0x7F, 0x07);
    writeRegister(0x40, 0x40);
    writeRegister(0x7F, 0x06);
    writeRegister(0x62, 0xF0);
    writeRegister(0x63, 0x00);
    writeRegister(0x7F, 0x0D);
    writeRegister(0x48, 0xC0);
    writeRegister(0x6F, 0xD5);
    writeRegister(0x7F, 0x00);
    writeRegister(0x5B, 0xA0);
    writeRegister(0x4E, 0xA8);
    writeRegister(0x5A, 0x50);
    writeRegister(0x40, 0x80);

    wait_ms(250);

    writeRegister(0x7F, 0x14);
    writeRegister(0x6F, 0x1C);
    writeRegister(0x7F, 0x00);

}
void grabData(void) {
    static int totalX = 0;
    static int totalY = 0;
    uint8_t check = 0;
    if(button_state == true){
        check = readRegister(0x02) & 0x80;
        if (check) {
            deltaX_low = readRegister(0x03);        //Grabs data from the proper registers.
            deltaX_high = (readRegister(0x04) << 8) & 0xFF00; //Grabs data and shifts it to make space to be combined with lower bits.
            deltaY_low = readRegister(0x05);
            deltaY_high = (readRegister(0x06) << 8) & 0xFF00;
    
            deltaY = deltaX_high | deltaX_low;      //Combines the low and high bits.
            deltaX = deltaY_high | deltaY_low;
            totalX += deltaX;
            totalY += deltaY;

        }
        GSS_X = totalX;
        GSS_Y = totalY;
    }
}

//motor
void ReadVelocity(){
    /*
    The velocity is calculated by follow :
    velocity = EncoderPosition /Encoder CPR (Counts per round) /gear ratio *2pi /dt
    unit : rad/sec
    */
    
    EncoderPositionA = TIM2->CNT ;
    EncoderPositionB = TIM3->CNT ;
    TIM2->CNT = 0;
    TIM3->CNT = 0;
    // rad/s
    velocityA = EncoderPositionA /HALL_RESOLUTION /GEAR_RATIO /dt *60;
    velocityB = EncoderPositionB /HALL_RESOLUTION /GEAR_RATIO /dt *60;
    // RPM
//    *velocityA = EncoderPositionA /64.0 /56.0 /dt *60.0;
//    *velocityB = EncoderPositionB /64.0 /56.0 /dt *60.0;
}


void motor_drive(float voltA, float voltB){
    // Input voltage is in range -12.5V ~ 12.5V
    if(abs(voltA) <= minimum_volt){
        if(voltA > 0){ voltA = minimum_volt; }
        else{ voltA = -minimum_volt; }
    }
    if(abs(voltB) <= minimum_volt){
        if(voltB > 0){ voltB = minimum_volt; }
        else{ voltB = -minimum_volt; }
    }
    
    // Convet volt to pwm
    uint16_t dutycycleA = (0.5f - 0.5f *voltA /INPUT_VOLTAGE) *uint16_t(TIM1->ARR);
    uint16_t dutycycleB = (0.5f - 0.5f *voltB /INPUT_VOLTAGE) *uint16_t(TIM1->ARR);
    TIM1->CCR1 = dutycycleA;
    TIM1->CCR2 = dutycycleB;
}


void control_speed(){
    float voltA;
    float voltB;
    // if receive 0 command than reset every thing
    if(VELOCITY_SPEED_A == 0 && VELOCITY_SPEED_B == 0)
    {
        velocityA = 0;
        velocityB = 0;
        last_voltA = 0;
        last_voltB = 0;
        errorA = 0;
        error_drA = 0;
        errorB = 0;
        error_drB = 0;
    }
    errorA = (VELOCITY_SPEED_A - velocityA);//(command from TX2 - read from odometry)
    voltA = last_voltA + 0.4f*errorA - 0.35f*error_drA;
    error_drA = errorA;
    last_voltA = voltA;
    if(abs(voltA) > INPUT_VOLTAGE){
        if(voltA > 0){voltA = INPUT_VOLTAGE;}
        else{voltA = -INPUT_VOLTAGE;}    
    }
    
    errorB = (VELOCITY_SPEED_B - velocityB);
    voltB = last_voltB + 0.4f*errorB - 0.35f*error_drB;
    error_drB = errorB;
    last_voltB = voltB;
    if(abs(voltB) > INPUT_VOLTAGE){
        if(voltB > 0){voltB = INPUT_VOLTAGE;}
        else{voltB = -INPUT_VOLTAGE;}    
    }
    
    motor_drive(voltA, voltB);

    //printf("%.3f, %.3f, %.3f\r\n",error1, last_error, voltA);
}


void InitEncoder(void) {
    // Hardware Quadrature Encoder AB for Nucleo F446RE
    // Output on debug port to host PC @ 9600 baud

    /* Connections
    PA_0 = Encoder1 A
    PA_1 = Encoder1 B
    PB_5 = Encoder2 A
    PB_4 = Encoder2 B
    */
    
    // configure GPIO PA0, PA1, PB5 & PB4 as inputs for Encoder
    RCC->AHB1ENR |= 0x00000003;  // Enable clock for GPIOA & GPIOB
 
    GPIOA->MODER   |= GPIO_MODER_MODER0_1 | GPIO_MODER_MODER1_1 ;           // PA0 & PA1 as Alternate Function  /*!< GPIO port mode register,               Address offset: 0x00      */
    GPIOA->PUPDR   |= GPIO_PUPDR_PUPDR0_0 | GPIO_PUPDR_PUPDR1_0 ;           // Pull Down                        /*!< GPIO port pull-up/pull-down register,  Address offset: 0x0C      */
    GPIOA->AFR[0]  |= 0x00000011 ;                                          // AF1 for PA0 & PA1                /*!< GPIO alternate function registers,     Address offset: 0x20-0x24 */
    GPIOA->AFR[1]  |= 0x00000000 ;                                          //                                  /*!< GPIO alternate function registers,     Address offset: 0x20-0x24 */
   
 
    GPIOB->MODER   |= GPIO_MODER_MODER4_1 | GPIO_MODER_MODER5_1 ;           // PB5 & PB4 as Alternate Function  /*!< GPIO port mode register,               Address offset: 0x00      */
    GPIOB->PUPDR   |= GPIO_PUPDR_PUPDR4_0 | GPIO_PUPDR_PUPDR5_0 ;           // Pull Down                        /*!< GPIO port pull-up/pull-down register,  Address offset: 0x0C      */
    GPIOB->AFR[0]  |= 0x00220000 ;                                          // AF2 for PB5 & PB4                /*!< GPIO alternate function registers,     Address offset: 0x20-0x24 */
    GPIOB->AFR[1]  |= 0x00000000 ;                                          //                                  /*!< GPIO alternate function registers,     Address offset: 0x20-0x24 */
   
    // configure TIM2 & TIM3 as Encoder input
    RCC->APB1ENR |= 0x00000003;  // Enable clock for TIM2 & TIM3

    TIM2->CR1   = 0x0001;     // CEN(Counter ENable)='1'     < TIM control register 1  
    TIM2->SMCR  = 0x0003;     // SMS='011' (Encoder mode 3)  < TIM slave mode control register
    TIM2->CCMR1 = 0xF1F1;     // CC1S='01' CC2S='01'         < TIM capture/compare mode register 1
    TIM2->CCMR2 = 0x0000;     //                             < TIM capture/compare mode register 2
    TIM2->CCER  = 0x0011;     // CC1P CC2P                   < TIM capture/compare enable register
    TIM2->PSC   = 0x0000;     // Prescaler = (0+1)           < TIM prescaler
    TIM2->ARR   = 0xffffffff; // reload at 0xfffffff         < TIM auto-reload register
  
    TIM2->CNT = 0x0000;  //reset the counter before we use it
 
    TIM3->CR1   = 0x0001;     // CEN(Counter ENable)='1'     < TIM control register 1    
    TIM3->SMCR  = 0x0003;     // SMS='011' (Encoder mode 3)  < TIM slave mode control register
    TIM3->CCMR1 = 0xF1F1;     // CC1S='01' CC2S='01'         < TIM capture/compare mode register 1
    TIM3->CCMR2 = 0x0000;     //                             < TIM capture/compare mode register 2
    TIM3->CCER  = 0x0011;     // CC1P CC2P                   < TIM capture/compare enable register
    TIM3->PSC   = 0x0000;     // Prescaler = (0+1)           < TIM prescaler
    TIM3->ARR   = 0xffffffff; // reload at 0xfffffff         < TIM auto-reload register
  
    TIM3->CNT = 0x0000;  //reset the counter before we use it
}


void InitMotor(float pwm_frequency){
    uint16_t reload = 90000000 /int(pwm_frequency * 1000) - 1;
    uint16_t stop   = 90000000 /int(pwm_frequency * 1000) /2 - 1;
    
    TIM1->CR1   &= (~0x0001);   // Set counter disable in Control Register 1 at initial
    TIM1->PSC    = 1U;          // Prescaler system clock (1 + PSC) for Timer 1
    TIM1->ARR    = reload;      // Set auto-reload, the pwm freq is (system clk /(1+PSC) /ARR)
    TIM1->CCMR1 |= 0x0808;      // Not necessary
    TIM1->CCER  |= 0x0055;      // Enable complementary mode for channel 1, channel 2
    TIM1->BDTR  |= 0x0C00;      // Set off-state selection
    TIM1->EGR    = 0x0001;      // Update generation
    TIM1->CR1   |= 0x0001;      // Counter enable
/*
    pc.printf("CR1 : %d\r",uint16_t(TIM1->CR1));
    pc.printf("PSC : %d\r",uint16_t(TIM1->PSC));
    pc.printf("ARR : %d\r",uint16_t(TIM1->ARR));
    pc.printf("CCMR1 : %x\r",TIM1->CCMR1);
    pc.printf("CCER : %x\r",TIM1->CCER);
    pc.printf("BDTR : %x\r",TIM1->BDTR);
    pc.printf("EGR : %x\r",TIM1->EGR);
    pc.printf("stop : %d\r",stop);
*/
    TIM1->CCR1 = stop;
    TIM1->CCR2 = stop;
    
//    bool cc1ne_bit = (TIM1->CCER >> 2) & 0x0001;
//    pc.printf("CC1NE bit : %d\r",cc1ne_bit);
}


void init_UART()
{
    pc.baud(460800);  // baud rate閮剔9600
    pc.attach(&RX_ITR, Serial::RxIrq);  // Attach a function(RX_ITR) to call whenever a serial interrupt is generated.
}


void RX_ITR()
{
    while(pc.readable()) {
        char uart_read;
        uart_read = pc.getc();
        if(uart_read == 115) {
            RX_flag2 = 1;
            readcount = 0;
            getData[5] = 0;
        } 
        if(RX_flag2 == 1) {
            getData[readcount] = uart_read;
            readcount++;
            if(readcount >= 6 & getData[5] == 101) {
                readcount = 0;
                RX_flag2 = 0;               
                ///code for decoding///
                data_received[0] = (getData[2] << 8) | getData[1];
                data_received[1] = (getData[4] << 8) | getData[3];    
//                VELOCITY_SPEED_A = data_received[0]/100;
//                VELOCITY_SPEED_B = data_received[1]/100;
                VELOCITY_SPEED_A = (float)data_received[0]/100.0f;
                VELOCITY_SPEED_B = (float)data_received[1]/100.0f;
                ///////////////////////
            }
        } 
    }
}