#include <stdio.h>
#include <stdint.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <linux/spi/spidev.h>

#define SPI_DEVICE "/dev/spidev1.0"

int main() {

    system("config-pin P2_25 spi");
    system("config-pin P2_27 spi");
    system("config-pin P2_29 spi_sclk");
    system("config-pin P2_31 spi_cs");
    system("echo out > /sys/class/gpio/gpio19/direction"); //CS pin
    
    int spi_fd;
    uint8_t tx_buffer[2] = {0x01, 0x02}; // Example data to send
    uint8_t rx_buffer[2] = {0};          // Buffer to store received data

    // Open SPI device
    spi_fd = open(SPI_DEVICE, O_RDWR);
    if (spi_fd < 0) {
        perror("Error opening SPI device");
        return 1;
    }
    
    int gpio_fd;
    gpio_fd = open("/sys/class/gpio/gpio19/value", O_WRONLY);
    if (gpio_fd < 0) {
        perror("Error opening CS GPIO");
        close(spi_fd);
        return 1;
    }
    // Pull CS pin high (inactive)
    write(gpio_fd, "1", 1);
    close(gpio_fd);

    // Configure SPI mode, speed, etc.
    // For example, set SPI mode to 0, maximum speed 1MHz
    uint8_t spi_mode = SPI_MODE_0;
    uint32_t spi_speed = 1000000; // 1MHz
    if (ioctl(spi_fd, SPI_IOC_WR_MODE, &spi_mode) < 0 ||
        ioctl(spi_fd, SPI_IOC_WR_MAX_SPEED_HZ, &spi_speed) < 0) {
        perror("Error setting SPI parameters");
        close(spi_fd);
        return 1;
    }

    // Pull CS pin low to select the device
    gpio_fd = open("/sys/class/gpio/gpio19/value", O_WRONLY);
    if (gpio_fd < 0) {
        perror("Error opening CS GPIO");
        close(spi_fd);
        return 1;
    }
    // Pull CS pin low (active)
    write(gpio_fd, "0", 1);
    close(gpio_fd);

    // Transfer data over SPI
    if (write(spi_fd, tx_buffer, sizeof(tx_buffer)) != sizeof(tx_buffer)) {
        perror("Error writing to SPI device");
        close(spi_fd);
        return 1;
    }
    if (read(spi_fd, rx_buffer, sizeof(rx_buffer)) != sizeof(rx_buffer)) {
        perror("Error reading from SPI device");
        close(spi_fd);
        return 1;
    }

    // Pull CS pin high to deselect the device
    gpio_fd = open("/sys/class/gpio/gpio19/value", O_WRONLY);
    if (gpio_fd < 0) {
        perror("Error opening CS GPIO");
        close(spi_fd);
        return 1;
    }
    // Pull CS pin high (inactive)
    write(gpio_fd, "1", 1);
    close(gpio_fd);

    // Print received data
    printf("Received data: 0x%02X, 0x%02X\n", rx_buffer[0], rx_buffer[1]);

    // Close SPI device
    close(spi_fd);

    return 0;
}