【瑞萨RA6E2】ADC 电压温度计

本文介绍了瑞萨 RA-Eco-RA6E2-64PIN-V1.0 开发板由 ADC 采集芯片温度和电压数据并串口打印，实现 ADC 电压温度计的项目设计。

项目介绍

瑞萨 RA6E2 Eco 开发板结合 ADC 温度传感器和ADC功能实现电压和温度测量的项目设计。

• 硬件连接：RA6E2开发板串口接线、ADC引脚通道接线；
• 流程图：代码和项目流程；
• 工程代码：ADC 配置和主程序；
• 效果演示：串口打印ADC电压和温度。

硬件连接

• 使用 Type-C 数据线连接开发板和电脑，用以串口通信；
• 使用 J-LINK 调试器连接板载 SWD 调试端口；
• 使用杜邦线连接 P000 引脚，用以测试 ADC 采样电压；

流程图

工程创建

• 打开 e^2^ studio 软件；
• 依次点击 文件 - 新建 - 瑞萨 C/C++ 项目 - Renesas RA ；
• 依次进行工程命名，路径设置，FSP版本，目标开发板选择，Device 选择 R7FA6E2BB3CFM ，工具链选择 GNU ARM Embedded ，调试器选择 J-Link ；
• 完成工程创建 ；

串口配置

• 进入 FSP 配置界面，打开 Pins 标签页，根据原理图或开发板丝印，将 P109 和 P110 引脚分别配置为 TXD9 和 RXD9 串口模式；

  

• 新建串口通信堆栈 New Stack - Connectivity - UART (r_sci_uart) ；

• 串口属性配置

  

• 进入 BSP 标签页，配置 RA Common 属性

  

ADC 配置

• 进入 Stacks 堆栈标签页，新建 ADC 堆栈 New Stack - Analog - ADC (r_adc) ；
• 选中 ADC 堆栈，进入属性选项；
• Input 选项下勾选 Channel 0 和 Temperature Sensor 选项；
• 中断配置 - Interrupts - Callback 值修改为 adc_callback - 优先级设置为 Priority 2 ；
• 引脚 Pins 开启 AN000 对应 P000 引脚；

• 配置完成后，点击 Generate Project Content 按钮，生成工程代码；
• 右键项目，构建工程，确保 0 报错。

代码

包括关键执行代码和官方示例代码。

关键代码

在项目文件目录中，打开 src/hal_entry.c 文件，添加如下关键代码

#include "hal_data.h"
#include <stdio.h>

fsp_err_t err = FSP_SUCCESS;
volatile bool uart_send_complete_flag = false;
void user_uart_callback (uart_callback_args_t * p_args)
{
    if(p_args->event == UART_EVENT_TX_COMPLETE)
    {
        uart_send_complete_flag = true;
    }
}

/*------------- UART redirection printf -------------*/
#ifdef __GNUC__
    #define PUTCHAR_PROTOTYPE int __io_putchar(int ch)
#else

#endif

PUTCHAR_PROTOTYPE
{
        err = R_SCI_UART_Write(&g_uart9_ctrl, (uint8_t *)&ch, 1);
        if(FSP_SUCCESS != err) __BKPT();
        while(uart_send_complete_flag == false){}
        uart_send_complete_flag = false;
        return ch;
}

int _write(int fd,char *pBuffer,int size)
{
    for(int i=0;i<size;i++)
    {
        __io_putchar(*pBuffer++);
    }
    return size;
}

/*------------- ADC callback -------------*/
volatile bool scan_complete_flag = false;
void adc_callback (adc_callback_args_t * p_args)
{
    FSP_PARAMETER_NOT_USED(p_args);
    scan_complete_flag = true;
}

/******************
 * ADC Temperature
 * （详见 https://renesas.github.io/fsp/group___a_d_c.html ）
 *******************/
/* 官方例程常数 */
#define VCC_UV           (3300000UL)   /* 3.3 V → μV */
#define RES_SHIFT        (12U)         /* 12-bit ADC */
#define REF_TEMP         (127)         /* 校准点 127 ℃ */
#define SLOPE_UV_PER_C   (4000L)       /* 4 mV/℃ → 4000 μV/℃ */

/* 获取ADC通道温度 */
static int32_t get_temperature_c(void)
{
    /* 1. 启动 ADC 并等待完成 */
    R_ADC_ScanStart(&g_adc0_ctrl);
    adc_status_t status = { .state = ADC_STATE_SCAN_IN_PROGRESS };
    while (status.state == ADC_STATE_SCAN_IN_PROGRESS)
    {
        R_ADC_StatusGet(&g_adc0_ctrl, &status);
    }

    /* 2. 读温度通道原始码值 */
    uint16_t raw;
    R_ADC_Read(&g_adc0_ctrl, ADC_CHANNEL_TEMPERATURE, &raw);

    /* 3. 取 127 ℃ 校准码值（TSCDR） */
    adc_info_t info;
    R_ADC_InfoGet(&g_adc0_ctrl, &info);
    int32_t cal127 = (int32_t)info.calibration_data;

    /* 4. 官方公式（单位 μV） */
    int32_t v1_uv   = (VCC_UV >> RES_SHIFT) * cal127;   /* 127 ℃ 对应电压 */
    int32_t vs_uv   = (VCC_UV >> RES_SHIFT) * raw;      /* 当前电压 */
    int32_t temp_c  = (vs_uv - v1_uv) / SLOPE_UV_PER_C + REF_TEMP;

    return temp_c;
}

/* 获取ADC原始数值和转换电压 */
static void get_adc_voltage(uint16_t *p_raw, float *p_volt)
{
    uint16_t adc_raw;
    /* 1. 启动 ADC 并等待完成 */
    R_ADC_ScanStart(&g_adc0_ctrl);
    adc_status_t status = { .state = ADC_STATE_SCAN_IN_PROGRESS };
    while (status.state == ADC_STATE_SCAN_IN_PROGRESS)
    {
        R_ADC_StatusGet(&g_adc0_ctrl, &status);
    }

    /* 2. 读adc通道原始码值 */
    err = R_ADC_Read(&g_adc0_ctrl, ADC_CHANNEL_0, &adc_raw);
    assert(FSP_SUCCESS == err);

    /* 3. ADC 电压转换 */
    float volt = (float)(adc_raw/4095.0)*3.3;

    /* 4. 返回数据 */
    *p_raw  = adc_raw;
    *p_volt = volt;
}

void hal_entry(void)
{
    /* TODO: add your own code here */
    err = R_SCI_UART_Open(&g_uart9_ctrl, &g_uart9_cfg);
    assert(FSP_SUCCESS == err);
    /* Initializes the module. */
    err = R_ADC_Open(&g_adc0_ctrl, &g_adc0_cfg);
    assert(FSP_SUCCESS == err);
    /* Enable temperature sensor. */
    err = R_ADC_ScanCfg(&g_adc0_ctrl, &g_adc0_channel_cfg);
    assert(FSP_SUCCESS == err);

    while (1)
    {
        int32_t temp_c = get_temperature_c();
        uint16_t adc_raw;
        float    volt;
        get_adc_voltage(&adc_raw, &volt);

        /* JSON 输出 */
        printf("{\"adc\": %u, \"volt\": %.3f, \"temp\": %ld}\r\n",adc_raw,volt,temp_c);
        R_BSP_SoftwareDelay(1000, BSP_DELAY_UNITS_MILLISECONDS);
    }
#if BSP_TZ_SECURE_BUILD
    /* Enter non-secure code */
    R_BSP_NonSecureEnter();
#endif
}

• 保存文件，右键项目 - 构建项目；
• 右键项目 - 调试项目 - 上传固件至开发板。

Demo 代码

有关 FSP 中 ADC 函数使用的官方示例代码如下，详见：RA Flexible Software Package Documentation: ADC (r_adc)

#define ADC_EXAMPLE_CALIBRATION_DATA_RA6M1               (0x7D5)
#define ADC_EXAMPLE_VCC_MICROVOLT                        (3300000)
#define ADC_EXAMPLE_TEMPERATURE_RESOLUTION               (12U)
#define ADC_EXAMPLE_REFERENCE_CALIBRATION_TEMPERATURE    (127)
void adc_temperature_example (void)
{
    /* The following example calculates the temperature using the data provided in the section
     * See "Preparation for Using the Temperature Sensor" in the TSN secton of the relevant hardware manual. */
    fsp_err_t err = FSP_SUCCESS;
    /* Initializes the module. */
    err = R_ADC_Open(&g_adc0_ctrl, &g_adc0_cfg);
    /* Handle any errors. This function should be defined by the user. */
    assert(FSP_SUCCESS == err);
    /* Enable temperature sensor. */
    err = R_ADC_ScanCfg(&g_adc0_ctrl, &g_adc0_channel_cfg);
    assert(FSP_SUCCESS == err);
    /* In software trigger mode, start a scan by calling R_ADC_ScanStart(). In other modes, enable external
     * triggers by calling R_ADC_ScanStart(). */
    (void) R_ADC_ScanStart(&g_adc0_ctrl);
    /* Wait for conversion to complete. */
    adc_status_t status;
    status.state = ADC_STATE_SCAN_IN_PROGRESS;
    while (ADC_STATE_SCAN_IN_PROGRESS == status.state)
    {
        (void) R_ADC_StatusGet(&g_adc0_ctrl, &status);
    }
    /* Read converted data. */
    uint16_t temperature_conversion_result;
    err = R_ADC_Read(&g_adc0_ctrl, ADC_CHANNEL_TEMPERATURE, &temperature_conversion_result);
    assert(FSP_SUCCESS == err);
    /* If the MCU does not provide calibration data, use the value in the hardware manual or determine it
     * experimentally. */
    /* Get Calibration data from the MCU if available. */
    int32_t    reference_calibration_data;
    adc_info_t adc_info;
    (void) R_ADC_InfoGet(&g_adc0_ctrl, &adc_info);
    reference_calibration_data = (int32_t) adc_info.calibration_data;
    /* NOTE: The slope of the temperature sensor varies from sensor to sensor. Renesas recommends calculating
     * the slope of the temperature sensor experimentally.
     *
     * This example uses the typical slope provided in Table "TSN characteristics"
     * in the relevant hardware manual. */
    int32_t slope_uv_per_c = BSP_FEATURE_TSN_SLOPE;
    /* Formula for calculating temperature copied from section "Preparation for Using the Temperature Sensor"
     * of the relevant hardware manual:
     *
     * In this MCU, the TSCDR register stores the temperature value (CAL127) of the temperature sensor measured
     * under the condition Ta = Tj = 127 C and AVCC0 = 3.3 V. By using this value as the sample measurement result
     * at the first point, preparation before using the temperature sensor can be omitted.
     *
     * If V1 is calculated from CAL127,
     * V1 = 3.3 * CAL127 / 4096 [V]
     *
     * Using this, the measured temperature can be calculated according to the following formula.
     *
     * T = (Vs - V1) / Slope + 127 [C]
     * T: Measured temperature (C)
     * Vs: Voltage output by the temperature sensor when the temperature is measured (V)
     * V1: Voltage output by the temperature sensor when Ta = Tj = 127 C and AVCC0 = 3.3 V (V)
     * Slope: Temperature slope given in Table 52.38 / 1000 (V/C)
     */
    int32_t v1_uv = (ADC_EXAMPLE_VCC_MICROVOLT >> ADC_EXAMPLE_TEMPERATURE_RESOLUTION) *
                    reference_calibration_data;
    int32_t vs_uv = (ADC_EXAMPLE_VCC_MICROVOLT >> ADC_EXAMPLE_TEMPERATURE_RESOLUTION) *
                    temperature_conversion_result;
    int32_t temperature_c = (vs_uv - v1_uv) / slope_uv_per_c + ADC_EXAMPLE_REFERENCE_CALIBRATION_TEMPERATURE;
    /* Expect room temperature, break if temperature is outside the range of 20 C to 25 C. */
    if ((temperature_c < 20) || (temperature_c > 25))
    {
        __BKPT(0);
    }
}

详见：RA Flexible Software Package Documentation: ADC (r_adc)

效果

• TypeC - USB 数据线连接开发板串口和电脑；
• 打开串口调试助手，配置对应的波特率等参数；
• 打开串口，即可接收芯片发送的 ADC 数值、电压和温度信息；

将 P000 引脚分别连接 3.3V 和 GND ，输出对应的电压值

总结

本文介绍了瑞萨 RA-Eco-RA6E2-64PIN-V1.0 开发板由 ADC 采集芯片温度和 P000 电压数据，并串口打印实现ADC温度计和电压测量的项目设计，为该产品在物联网领域的开发设计和快速应用提供了参考。