File content as of revision 0:36cebc939c49:

#include "mbed.h"
#include "rtos.h"

#define SPI_SPEED   (10000000)

BusOut Leds(PA_8, PB_10, PB_4, PB_5);
BusIn Switches(PA_0, PA_1, PA_4, PB_0, PC_1, PC_0);

SPI SpiM(PA_7, PA_6, PA_5); // mosi, miso, sclk
DigitalOut SpiMCs(PB_6);

uint8_t prevSendVal = 0x00;

int main()
{
    printf("\r\n\nNucleo rtos SPI Master Test..\r\n");
    
    // LED Check
    for (int i = 0; i <  5; i++) {
        Leds.write(0x0f);
        Thread::wait(100);
        Leds.write(0x00);
        Thread::wait(100);
    }
    
    // Setup Switches
    Switches.mode(PullUp);
    /*
    while(1) {
        printf("%x\r\n", ~Switches.read() &0x3f);
        Thread::wait(100);
    }
    */
    
    // Setup SPI
    SpiMCs = 1;
    SpiM.format(8, 0);
    SpiM.frequency(SPI_SPEED);
    
    for (;;) {
        uint8_t sendVal = ~Switches.read();
        
        if (prevSendVal != sendVal) {
            SpiMCs = 0;
            uint8_t receivedVal = SpiM.write(sendVal);
            SpiMCs = 1;
            
            prevSendVal = sendVal;
            
            Leds.write(receivedVal & 0x0f);
        }
    }
}