pressure_rig_16.cpp

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

using namespace std; 

float VREF = 5.0; 
float RES = pow(2,12); 
float G = 1.0; 
float B = 0.06; 
float A = 8.15; 


int send_pressure(float p, const uint cs_pin, spi_inst_t *spi, uint16_t number) 
{
    int bytes; 
    uint16_t settings = 0x7; // 0111
    settings = settings << 12;

    float vout = ((p - B) / A); 
    
    float dac_float = (vout / 5.0) * 4096.0;
    uint16_t dac_val = static_cast<uint16_t>(dac_float);

    printf("Sending data to DAC \n"); 
    printf("Expected VOUT %f\n",vout); 
    printf("Expected message 0x%X\n", dac_val); 

    uint16_t new_message_16bit = settings | dac_val; 
    const uint16_t* src = &new_message_16bit; 

    gpio_put(cs_pin, 0); 
    bytes = spi_write16_blocking(spi, src, 1); 
    gpio_put(cs_pin, 1); 

    return 0; 
}

int read_pressure(const uint cs_pin, spi_inst_t *spi)
{
    uint8_t buffer[2]; 
    //uint16_t buffers[2];  
    uint16_t value; 
    uint16_t *dst = &value; 
    int half_word; 
    uint16_t result; 
    const float conversion_factor = 3.3f / (1 << 12);

    {
        gpio_put(cs_pin, 0); 
        //sleep_ms (2 * 1000);
        half_word = spi_read16_blocking(spi, 0, dst, 1);
        printf("Half Word Returned: %d", half_word); 
        // sleep_ms (2 * 1000);
        // printf("IS SPI Busy: %d \n", spi_is_busy(spi));
        // printf("Buffer 1 = %d ", buffer[0]);
        // printf("Buffer 1 = 0x%x \n", buffer[0]);
        // printf("Buffer 2 = %d ", buffer[1]);
        // printf("Buffer 2 = 0x%x \n", buffer[1]);
        printf("Buffer 2 = %d ", value);
        printf("Buffer 2 = 0x%x \n", value);
        gpio_put(cs_pin, 1); 
        printf("Voltage = %f \n",(value * conversion_factor));

        //need to drop the first bit from buffer[0]
        // result = (buffer[0] >> 1); //buffer is now 4 bits 
        // result = (buffer[0] << 8) | (buffer[1]); 
        // //concatenate both buffers to get the full 12 bit result from the mcp3301 
        // printf("Result = 0x%x \n",result); 
        // printf("Result = %d \n",result);
        printf("Voltage = %f \n",(value * conversion_factor));
        // printf("\n"); 
    }
    return 0; 
}

int main ()
{
    // MOSI TX
    // MISO RX
    int val; 
    uint16_t value = 0x88;
    
    const uint sck_pin = 2;   //CLOCK PIN
    const uint mosi_pin = 3;  //MOSI TX 
    const uint miso_pin = 4;  //MISO RX
    uint cs_pin = 1;  //GP5 
    const uint cs_pin_dac = 8; //GP8 can be made into a chip select
    spi_inst_t *spi = spi0;

    stdio_init_all(); //Initialize all pins 
    sleep_ms(8500);
    printf("SPI protocal begin \n"); 

    // Setup SPI on Pico
    spi_init(spi, 90000); 
    sleep_ms(10000); 


    spi_set_format(spi0,               // SPI instance
                16,                   // Number of bits per transfer
                SPI_CPOL_1,          // Polarity (CPOL)
                SPI_CPHA_1,         // Phase (CPHA)
                SPI_MSB_FIRST);



    // Initalize Pins
    gpio_set_function(miso_pin,GPIO_FUNC_SPI);
    gpio_set_function(mosi_pin,GPIO_FUNC_SPI);
    gpio_set_function(sck_pin,GPIO_FUNC_SPI); 

    gpio_init(cs_pin); 
    gpio_set_dir(cs_pin, GPIO_OUT);
    gpio_put(cs_pin, 1); 

    gpio_init(cs_pin_dac); 
    gpio_set_dir(cs_pin_dac, GPIO_OUT); 
    gpio_put(cs_pin_dac,1); 

    // has to run in a loop
    while(1)
    {
        send_pressure(5.8,cs_pin_dac,spi,value);
        sleep_ms(1000);
    }
    return 0; 
}