rc_spi_loopback.c

/**
 * @example    rc_spi_loopback.c
 *
 * This is a test to check read and write operation of the SPI1 bus. For this
 * example to work, connect the MISO and MOSI wires of one of the included 6-pin
 * JST-SH pigtails and plug into either SPI1 socket. The test strings this
 * programs transmits out the MOSI channel will loop back in the MISO channel
 * and be read.
 */

#include <stdio.h>
#include <string.h>
#include <rc/spi.h>

// change these for your platform
// on BB this is equivilant to RC_BB_SPI1_SS1
#define BUS             1
#define SLAVE           0


#define BUS_MODE        SPI_MODE_0
#define SPI_SPEED       24000000

int main()
{
        char* test_str = "Hello World";

        // get number of bytes in test string, add 1 for the terminating null
        // character which strlen omits
        int bytes = strlen(test_str)+1;

        char buf[32];   // read buffer
        int ret;        // return value

        printf("Make sure the MISO and MOSI lines are connected with\n");
        printf("a loopback jumper which is necessary for this test.\n");
        printf("Testing SPI \n\n");
        if(rc_spi_init_auto_slave(BUS, SLAVE, BUS_MODE, SPI_SPEED)){
                return -1;
        }

        // attempt a string send/receive transfer
        printf("transfer test:\n");
        printf("Sending %d bytes: %s\n", bytes, test_str);
        ret = rc_spi_transfer(BUS, SLAVE, (uint8_t*)test_str, bytes, (uint8_t*)buf);
        if(ret<0){
                printf("send failed\n");
                rc_spi_close(SLAVE);
                return -1;
        }
        else printf("Received %d bytes: %s\n",ret, buf);\


        rc_spi_close(BUS);
        return 0;
}