Raspberry Pi picoでSPI接続の気温センサーADT7310を使う

以下、CMakeLists.txt



cmake_minimum_required(VERSION 3.12)

# Pull in PICO SDK (must be before project)
include(/d/pico-sdk/pico/pico-sdk/external/pico_sdk_import.cmake)

project(test_adt7310_usb01_project)
set(CMAKE_C_STANDARD 11)
set(CMAKE_CXX_STANDARD 17)

# Initialize the SDK
pico_sdk_init()
add_executable(test_adt7310_usb01 test_adt7310_usb01.c)
target_link_libraries(test_adt7310_usb01 pico_stdlib hardware_spi)

pico_enable_stdio_usb(test_adt7310_usb01 1)
pico_enable_stdio_uart(test_adt7310_usb01 0)

pico_add_extra_outputs(test_adt7310_usb01)






以下、test_adt7310_usb01.c


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

#define PIN_MISO 16    // GPIO16 (21番ピン)
#define PIN_CS   17    // GPIO17 (22番ピン)
#define PIN_SCK  18    // GPIO18 (24番ピン)
#define PIN_MOSI 19    // GPIO19 (25番ピン)

#define SPI_PORT spi0

static inline void cs_select();
static inline void cs_deselect();
void write_register(uint8_t reg, uint8_t data);
void read_registers(uint8_t reg, uint8_t *buf, uint16_t len);
void loop(void);

int main() {
    stdio_init_all();

    // This example will use SPI0 at 0.5MHz.
    spi_init(SPI_PORT, 125 * 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);

    spi_set_format(SPI_PORT, 8, SPI_CPOL_1, SPI_CPHA_1, SPI_MSB_FIRST);   // SPI MODE3, MSBFIRST

    // ADT7310 ソフトウェアリセット
    uint8_t buf01[4] = {0xff, 0xff, 0xff, 0xff};
    cs_select();
    spi_write_blocking(SPI_PORT, buf01, 4);
    cs_deselect();
    sleep_ms(100);

    while (1) {
        loop();
    }

    return 0;
}

void loop(void) {
    double temp = 0.0;
    int32_t temp_raw = 0;
    uint8_t val[2];

    // 16bit 1-shot
    uint8_t data01 = 0xa0;

    //// 13bit 1-shot
    //uint8_t data01 = 0x20;

    write_register((uint8_t)0x08, data01);

    long long read_wait_time01 = time_us_64();
    sleep_ms(250);

    uint8_t status_reg = 0;
    int count001 = 0;

    while (1) {
        // 10ms待機
        sleep_ms(10);

        // ステータスレジスタの読み込み
        read_registers((uint8_t)0x40, &status_reg, (uint16_t)1);

        if (count001 >= 500) {
            break;
        }
        if ((((int)status_reg >> 7) & 1) == 0) {
            break;
        }
        count001++;
    }

    // ADT7410のステータスレジスタの値の表示
    //printf("status=0x%02x, count001=%d, %lld ms\r\n", (int)status_reg, count001, (time_us_64() - read_wait_time01) / 1000LL);

    sleep_ms(10);

    read_registers((uint8_t)0x50, val, 2);
    temp_raw = (int32_t)(((uint32_t)val[0] << 8) | (uint32_t)val[1]);

    //printf("temp_raw = 0x%08x\r\n", temp_raw);

    // 16bitの計算
    if (temp_raw >= 32768) {
        temp_raw -= 65536;
    }
    temp = temp_raw / 128.0;

    //// 13bitの計算
    //temp_raw = temp_raw >> 3;
    //if (temp_raw >= 4096) {
    //    temp_raw -= 8192;
    //}
    //temp = temp_raw / 16.0;

    printf("Temp    : %.4f degC\r\n", temp);

    sleep_ms(5000);
}

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 write_register(uint8_t reg, uint8_t data) {
    uint8_t buf[2];
    buf[0] = reg;
    buf[1] = data;
    cs_select();
    spi_write_blocking(SPI_PORT, buf, 2);
    cs_deselect();
}

void read_registers(uint8_t reg, uint8_t *buf, uint16_t len) {
    cs_select();
    spi_write_blocking(SPI_PORT, &reg, 1);
    spi_read_blocking(SPI_PORT, 0, buf, len);
    cs_deselect();
}