Mity CPU Platforms » MitySOM-5CSX Altera Cyclone V

#include <stdint.h>

#include <unistd.h>

#include <stdio.h>

#include <stdlib.h>

#include <getopt.h>

#include <fcntl.h>

#include <sys/ioctl.h>

#include <linux/types.h>

#include <linux/spi/spidev.h>

#include <iostream>

#include <chrono>

// ... test framework, etc.

const size_t SPI_BUFFER_SIZE = 4;

uint16_t spi_tx_buffer[SPI_BUFFER_SIZE];

uint16_t spi_rx_buffer[SPI_BUFFER_SIZE];

struct spi_ioc_transfer xfer[1];

int spi_init()

{

    int file;

    uint8_t mode, lsb, bits;

    uint32_t speed;

    if ((file = open("/dev/spidev32766.0", O_RDWR)) < 0)

    {

        printf("Failed to open the bus.");

        return -1;

    }

// ... mode reading and writing

    printf("file: spi mode %d, %d bits %sper word, %d Hz max\n", mode, bits, lsb ? "(lsb first) " : "", speed);

    memset(xfer, 0, sizeof(spi_ioc_transfer));

    xfer[0].tx_buf = (unsigned long)spi_tx_buffer;

    xfer[0].len = 20;       // Length of command to write

    xfer[0].cs_change = 1;  // Do NOT Keep CS activated

    xfer[0].delay_usecs = 0;

    xfer[0].speed_hz = 100000;

    xfer[0].bits_per_word = 16;

    return file;

}

uint16_t* spi_read(int file)

{

    int status;

    memset(spi_tx_buffer, 0, sizeof spi_tx_buffer);

    memset(spi_rx_buffer, 0, sizeof spi_rx_buffer);

    spi_tx_buffer[0] = 0x8330;

    xfer[0].tx_buf = (unsigned long)spi_tx_buffer;

    xfer[0].len = 2; // Length of command to write/read

    xfer[0].rx_buf = (unsigned long)spi_rx_buffer;

    status = ioctl(file, SPI_IOC_MESSAGE(1), xfer);

    if (status < 0)

    {

        perror("SPI_IOC_MESSAGE");

    }

    // Allow way more than enough time for transfer to occur

    sleep(1);

    printf("rx: ");

    for (uint16_t i = 0; i < SPI_BUFFER_SIZE; i++)

    {

        printf("%04X ", spi_rx_buffer[i]);

    }

    printf("\n");

    return spi_rx_buffer;

}

void main()

{

    int spidev_fd = spi_init();

    if (spidev_fd < 0)

    {

        printf("Failed to open!");

        return;

    }

    // Timeout after 10 seconds

    std::cout << "STARTING SPI" << std::endl;

    auto timeout_time = std::chrono::high_resolution_clock::now() + std::chrono::seconds(10);

    while (std::chrono::high_resolution_clock::now() < timeout_time)

    {

        spi_read(spidev_fd); //reading the address 0xE60E

        std::cout << "BUFFER: " << spi_rx_buffer << std::endl;

        usleep(100000);

    }

    close(spidev_fd);

}