跑马灯和ADC+UART已经在前两个程序做好，接下来RS485读取SHT20并通过串口发送出来。

测试SHT20

由此可以知道协议数据为： 01 04 00 01 00 02
通过 在线计算crc modbus.

故发起请求的数据为：01 04 00 01 00 02 20 0b

获取到的数据为: 01 04 04 00 b0 02 6c fb 2e
温度数据为： 00 b0 对应为0x00b0 获取到的温度值为17.6℃
湿度数据为： 02 6c 对应为0x026c 获取到的湿度值为62%。

硬件原理图 + FSP代码配置

前一篇帖子已经将UART口配置成printf做了说明我这里不再做说明。

RS485接口1

通过原理可以知道RS485使用的是UART5串口，对应的管脚是P502(RXD5)和P501(TXD5),P503是RS485收发状态切换，其中低电平表示收，高电平表示发。

FSP代码配置

UART配置

串口5使能。

New Statck->Connectivity->UART(r_sci_uart)来配置UART模块。

DIR配置（GPIO）

修改RS485 Thread

#include "rs485_thread.h"
/* RS485_Thread entry function */
/* pvParameters contains TaskHandle_t */
#include <stdio.h>
void UART4_Init(void);

void UART5_Init(void);
void sht20_process(void);


void UART4_Init(void)
{
    fsp_err_t err = FSP_SUCCESS;

    err = R_SCI_UART_Open(&g_uart4_ctrl, &g_uart4_cfg);
    assert(FSP_SUCCESS == err);
}

volatile bool uart4_send_complete_flag = false;

void uart4_callback(uart_callback_args_t * p_args)
{
    switch (p_args->event)
    {
        case UART_EVENT_RX_CHAR:
        {
            break;
        }
        case UART_EVENT_TX_COMPLETE:
        {
            uart4_send_complete_flag = true;
            break;
        }
        default:
            break;

    }
}

#if defined __GNUC__ && !defined __clang__
int _write(int fd, char *pBuffer, int size);

int _write(int fd, char *pBuffer, int size)
{
    (void)fd;
    R_SCI_UART_Write(&g_uart4_ctrl, (uint8_t *)pBuffer, (uint32_t)size);
    while(uart4_send_complete_flag == false);
    uart4_send_complete_flag = false;
    return size;
}

#else
int fputc(int ch, FILE *f)
{
    (void)f;
    R_SCI_UART_Write(&g_uart4_ctrl, (uint8_t *)&ch, 1);
    while(uart4_send_complete_flag == false);
    uart4_send_complete_flag = false;
    return ch;
}
#endif

void UART5_Init(void)
{
    fsp_err_t err = FSP_SUCCESS;

    err = R_SCI_UART_Open(&g_uart5_ctrl, &g_uart5_cfg);
    assert(FSP_SUCCESS == err);
}
volatile bool uart5_send_complete_flag = false;
volatile bool uart5_recv_complete_flag = false;
void uart5_callback(uart_callback_args_t * p_args)
{
    switch (p_args->event)
    {
        case UART_EVENT_RX_CHAR:
        {
            break;
        }
        case UART_EVENT_RX_COMPLETE:
        {
            uart5_recv_complete_flag = true;
            break;
        }
        case UART_EVENT_TX_COMPLETE:
        {
            uart5_send_complete_flag = true;
            break;
        }
        default:
            break;

    }
}

void sht20_process(void)
{
    uint8_t send_data[] = {0x01, 0x04, 0x00, 0x01, 0x00, 0x02, 0x20, 0x0b};
    uint8_t recv_data[9];
    uint16_t humid = 0;
    uint16_t thermo = 0;
    double humid_value = 0.0;
    double thermo_value = 0.0;
    R_IOPORT_PinWrite(&g_ioport_ctrl, BSP_IO_PORT_05_PIN_03, BSP_IO_LEVEL_HIGH);
    R_SCI_UART_Write(&g_uart5_ctrl, send_data, sizeof send_data);
    uart5_send_complete_flag = false;
    while(!uart5_send_complete_flag)
    {
        ;
    }
    R_IOPORT_PinWrite(&g_ioport_ctrl, BSP_IO_PORT_05_PIN_03, BSP_IO_LEVEL_LOW);
    R_SCI_UART_Read(&g_uart5_ctrl, recv_data, sizeof recv_data);
    uart5_recv_complete_flag = false;
    while(!uart5_recv_complete_flag)
    {
        ;
    }

    thermo  =  (uint16_t)recv_data[3] << 8|recv_data[4];
    humid = (uint16_t)recv_data[5] << 8|recv_data[6];
    humid_value = (double)humid/10.0;
    thermo_value = (double)thermo/10.0;
    printf("thermo: %f, humid: %f\r\n", thermo_value, humid_value);
}


void rs485_thread_entry(void *pvParameters)
{
    FSP_PARAMETER_NOT_USED (pvParameters);

    /* TODO: add your own code here */
    UART4_Init();
    UART5_Init();
    while (1)
    {
        sht20_process();
        vTaskDelay (1000);
    }
}