初めてのRaspberry Pi Pico ㉑ C言語 12ビットADC MCP3208

/**
 * Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

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

#define PIN_MISO 4
#define PIN_CS   5
#define PIN_SCK  2
#define PIN_MOSI 3

#define SPI_PORT spi0
static float Vref = 3.30;


static inline void cs_select() {
    asm volatile("nop \n nop \n nop");
    gpio_put(PIN_CS, 0);  // Active low
    asm volatile("nop \n nop \n nop");
}

static inline void cs_deselect() {
    asm volatile("nop \n nop \n nop");
    gpio_put(PIN_CS, 1);
    asm volatile("nop \n nop \n nop");
}

void setup_SPI(){
    // This example will use SPI0 at 0.5MHz.
    spi_init(SPI_PORT, 500 * 1000);
    gpio_set_function(PIN_MISO, GPIO_FUNC_SPI);
    gpio_set_function(PIN_SCK, GPIO_FUNC_SPI);
    gpio_set_function(PIN_MOSI, GPIO_FUNC_SPI);

    // Chip select is active-low, so we'll initialise it to a driven-high state
    gpio_init(PIN_CS);
    gpio_set_dir(PIN_CS, GPIO_OUT);
    gpio_put(PIN_CS, 1);
}

int readADC(uint8_t ch){
    uint8_t writeData[] = {0b00000110, 0x00, 0xff};
    switch(ch){
      case 0:
        writeData[0] = 0b00000110;
        writeData[1] = 0b00000000; 
      break;
      case 1:
        writeData[0] = 0b00000110;
        writeData[1] = 0b01000000; 
      break;
      case 2:
        writeData[0] = 0b00000110;
        writeData[1] = 0b10000000; 
      break;
      case 3:
        writeData[0] = 0b00000110;
        writeData[1] = 0b11000000; 
      break;
      case 4:
        writeData[0] = 0b00000111;
        writeData[1] = 0b00000000; 
      break;
      case 5:
        writeData[0] = 0b00000111;
        writeData[1] = 0b01000000; 
      break;
      case 6:
        writeData[0] = 0b00000111;
        writeData[1] = 0b10000000; 
      break;
      case 7:
        writeData[0] = 0b00000111;
        writeData[1] = 0b11000000; 
    }
    // printf("\n %0b %0b %0b\n",writeData[0],writeData[1],writeData[2]);
    uint8_t buffer[3];
    cs_select();
    sleep_ms(1);
    spi_write_read_blocking(SPI_PORT, writeData, buffer, 3);
    sleep_ms(1);
    cs_deselect();

    return (buffer[1] & 0x0f) << 8 | buffer[2];
}

int main() {
    stdio_init_all();

    printf("\nHello, MCP3208 Reading raw data from registers via SPI...\n");

    setup_SPI();

    for (uint8_t i=0; i<8; i++){
        printf("ch%d is %.4fV\n", i, Vref * readADC(i) / 4096);
    }
    return 0;
}