File content as of revision 1:c828f7c35fae:

#include "mbed.h"

I2CSlave slave(PB_7,PB_6);


DigitalOut InA1(D12);
DigitalOut InB1(D11);
PwmOut pwm1(D10);

DigitalOut InA2(D9);
DigitalOut InB2(D7);
PwmOut pwm2(D3);

DigitalOut InA3(D1);
DigitalOut InB3(D0);
PwmOut pwm3(D2);

void rec_eve();
void motor(int ch,int power);

int main(){
    wait(0.2);
    slave.address(0x14);
    pwm1.period(0.00052);
    pwm2.period(0.00052);
    pwm3.period(0.00052);
    while (1) {
        if(slave.receive() == I2CSlave::WriteAddressed){
            rec_eve();
        }
    }
}

void rec_eve(){
    char i2c_rec_buf[] = {0,0,0,0,0,0}; 
    slave.read(i2c_rec_buf,6);
    for(int i = 0; i< 6;i++){
        if(i2c_rec_buf[i] == 0){
            motor(i,0);
        }
        else if(i2c_rec_buf[i] == 128 ){
            motor(i,999);
        }
        else if(i2c_rec_buf[i] < 128){
            motor(i,i2c_rec_buf[i]);
        }
        else{
            motor(i,-1*(i2c_rec_buf[i] - 128));
        }
    }
}

void motor(int ch,int power){
    
    switch (ch){
    case 0://right
        if(power == 0){
            InA1 = 0;
            InB1 = 0;
            pwm1 = 0;     
        }
        else if(power == 999){
            InA1 = 1;
            InB1 = 1;
            pwm1 = 1;  
        }
        else if(power < 0){
            InA1 = 0;
            InB1 = 1;
            pwm1 = -1*(float)power/100; 
        }
        else{
            InA1 = 1;
            InB1 = 0;
            pwm1 = (float)power/100; 
        }
        break;
    case 5://back
        if(power == 0){
            InA2 = 0;
            InB2 = 0;
            pwm2 = 0;     
        }
        else if(power == 999){
            InA2 = 1;
            InB2 = 1;
            pwm2 = 1;  
        }
        else if(power < 0){
            InA2 = 0;
            InB2 = 1;
            pwm2 = -1*(float)power/100; 
        }
        else{
            InA2 = 1;
            InB2 = 0;
            pwm2 = (float)power/100; 
        }
        break;
    case 2://left
        if(power == 0){
            InA3 = 0;
            InB3 = 0;
            pwm3 = 0;     
        }
        else if(power == 999){
            InA3 = 1;
            InB3 = 1;
            pwm3 = 1;  
        }
        else if(power < 0){
            InA3 = 0;
            InB3 = 1;
            pwm3 = -1*(float)power/100; 
        }
        else{
            InA3 = 1;
            InB3 = 0;
            pwm3 = (float)power/100; 
        }
        break;
    default:
        break;
    }
}