File content as of revision 1:81cca0074c0d:

#include "mbed.h"
#include "BLEPeripheral.h"
#include "motordriver.h"
#include "stdint.h"

//*******************************
// Must define Serial serial and SPI spi
// BLE_RDY and BLE_REQ
//*******************************

Serial serial(USBTX, USBRX);
// The SPI construct, REQN and RDYN IO construct should be modified manually
// It depend on the board you are using and the REQN&RDYN configuration on BLE Shield
SPI spi(p5, p6, p7);
DigitalInOut BLE_RDY(p8);
DigitalInOut BLE_REQ(p9);
DigitalInOut BLE_RST(p10);

// Motor pins
Motor left(p21, p22, p23, 1); // pwm, fwd, rev, has brake feature
Motor right(p26,p25,p24, 1);

// IR sensors
//AnalogIn ir_c(p20); // center
//AnalogIn ir_l(p19); // left
//AnalogIn ir_r(p18); // right

/*----- BLE Utility -------------------------------------------------------------------------*/
// create peripheral instance, see pinouts above
BLEPeripheral            blePeripheral        = BLEPeripheral(&BLE_REQ, &BLE_RDY, &BLE_RST);

// create service
BLEService               uartService          = BLEService("713d0000503e4c75ba943148f18d941e");

// create characteristic
BLECharacteristic    txCharacteristic = BLECharacteristic("713d0002503e4c75ba943148f18d941e", BLENotify, 20);
BLECharacteristic    rxCharacteristic = BLECharacteristic("713d0003503e4c75ba943148f18d941e", BLEWriteWithoutResponse, 20);
/*--------------------------------------------------------------------------------------------*/

// Bluetooth variables
unsigned char buf[16] = {0};
unsigned char len = 0;

// Motor variables
float leftval = 0;
float rightval = 0;

int main()
{
    //serial.baud(9600);
    //serial.printf("Serial begin!\r\n");

    /*----- BLE Utility ---------------------------------------------*/
    // set advertised local name and service UUID
    blePeripheral.setLocalName("BLE Shield");

    blePeripheral.setAdvertisedServiceUuid(uartService.uuid());

    // add service and characteristic
    blePeripheral.addAttribute(uartService);
    blePeripheral.addAttribute(rxCharacteristic);
    blePeripheral.addAttribute(txCharacteristic);

    // begin initialization
    blePeripheral.begin();
    //serial.printf("BLE UART Peripheral begin!\r\n");
    /*---------------------------------------------------------------*/

    while(1) {
        BLECentral central = blePeripheral.central();

        if(central) {
            // central connected to peripheral
            //serial.printf("Connected to central\r\n");

            while (central.connected()) {
                // central still connected to peripheral
                if (rxCharacteristic.written()) {
                    unsigned char len = rxCharacteristic.valueLength();
                    const unsigned char *val = rxCharacteristic.value();

                    // Calculate differential motor values from cartesian joystick coordinates
                    // 0 = north, 1 = south, 2 = east, 3 = west
                    leftval = sqrt(pow((float)val[0]/255,2) + pow((float)val[2]/255,2)) - sqrt(pow((float)val[1]/255,2) + pow((float)val[3]/255,2));
                    rightval = sqrt(pow((float)val[0]/255,2) + pow((float)val[3]/255,2)) - sqrt(pow((float)val[1]/255,2) + pow((float)val[2]/255,2));

                    // Windup compensation
                    if (leftval > 1) leftval = 1;
                    if (leftval < -1) leftval = -1;
                    if (rightval > 1) rightval = 1;
                    if (rightval < -1) rightval = -1;

                    // Set motor speed values
                    left.speed(leftval);
                    right.speed(rightval);

                    //serial.printf("%f,   %f\n", leftval, rightval);
                }
            }
            // central disconnected
            //serial.printf("Disconnected from central\r\n");
        }
    }
}