#include <stdio.h>
#include "pico/stdlib.h"
#include "hardware/spi.h"

// Define MAX31865 SPI commands
#define READ_REGISTER   0x00
#define WRITE_REGISTER  0x80

// Define MAX31865 registers
#define CONFIG_REGISTER 0x00
#define RTD_MSB_REGISTER 0x01
#define RTD_LSB_REGISTER 0x02

// Function to read 16-bit value from MAX31865 register
uint16_t readRegister(spi_inst_t *spi, uint8_t reg) {
    uint8_t tx_data[2] = {READ_REGISTER | reg, 0};
    uint8_t rx_data[2] = {0};

    spi_write_read_blocking(spi, tx_data, rx_data, 2);

    return ((rx_data[0] << 8) | rx_data[1]);
}

// Function to initialize MAX31865
void initMAX31865(spi_inst_t *spi) {
    // Set configuration register (2-wire mode)
    uint16_t config = 0x0000; // Example configuration, change as needed
    uint8_t tx_data[2] = {(uint8_t)(WRITE_REGISTER | CONFIG_REGISTER), (uint8_t)(config >> 8), (uint8_t)config};
    spi_write_blocking(spi, tx_data, 3);
}

// Function to read temperature from MAX31865
float readTemperature(spi_inst_t *spi) {
    uint16_t rtd = readRegister(spi, RTD_MSB_REGISTER);
    return ((float)rtd / 32.0); // Example conversion, adjust for your sensor
}

int main() {
    stdio_init_all();

    // Initialize SPI0 with a baud rate of 500kHz, using GPIO 4, 5, and 6 for MISO, MOSI, and SCLK respectively
    spi_init(spi0, 500 * 1000);
    gpio_set_function(8, GPIO_FUNC_SPI);
    gpio_set_function(7, GPIO_FUNC_SPI);
    gpio_set_function(6, GPIO_FUNC_SPI);

    // Set up CS pin for MAX31865 (Example: GPIO 7)
    gpio_init(9);
    gpio_set_dir(9, GPIO_OUT);
    gpio_put(9, 1); // Set CS pin high initially

    initMAX31865(spi0); // Initialize MAX31865

    while (true) {
        float temperature = readTemperature(spi0); // Read temperature
        printf("Temperature: %.2f degrees Celsius\n", temperature);
        sleep_ms(1000); // Wait for 1 second
    }

    return 0;
}