freemodbus V1.6从机上电死机问题

发布于 2023-03-10 13:28:19 浏览：699 订阅该版

在mbrtu.c文件中的eMBRTUInit初始化函数中调用xMBPortSerialInit开始串口中断后，在调用xMBPortTimersInit前发生了串口中断的话会导致死机，因此时还未调用xMBPortTimersInit初始化"slave timer"定时器，而串口中断处理函数会调用serial_rx_ind函数，最后会导致在"slave timer"定时器未初始化的情况下调用vMBPortTimersEnable去开启"slave timer"定时器而死机。

```c
if( xMBPortSerialInit( ucPort, ulBaudRate, 8, eParity ) != TRUE )
    {
        eStatus = MB_EPORTERR;
    }
    else
    {
        /* If baudrate > 19200 then we should use the fixed timer values
         * t35 = 1750us. Otherwise t35 must be 3.5 times the character time.
         */
        if( ulBaudRate > 19200 )
        {
            usTimerT35_50us = 35;       /* 1800us. */
        }
        else
        {
            /* The timer reload value for a character is given by:
             *
             * ChTimeValue = Ticks_per_1s / ( Baudrate / 11 )
             *             = 11 * Ticks_per_1s / Baudrate
             *             = 220000 / Baudrate
             * The reload for t3.5 is 1.5 times this value and similary
             * for t3.5.
             */
            usTimerT35_50us = ( 7UL * 220000UL ) / ( 2UL * ulBaudRate );
        }
        if( xMBPortTimersInit( ( USHORT ) usTimerT35_50us ) != TRUE )
        {
            eStatus = MB_EPORTERR;
        }
    }
```
我更改为先初始化xMBPortTimersInit后再初始化xMBPortSerialInit后，暂未发现死机现象。

```c
/* If baudrate > 19200 then we should use the fixed timer values
         * t35 = 1750us. Otherwise t35 must be 3.5 times the character time.
         */
        if( ulBaudRate > 19200 )
        {
            usTimerT35_50us = 35;       /* 1800us. */
        }
        else
        {
            /* The timer reload value for a character is given by:
             *
             * ChTimeValue = Ticks_per_1s / ( Baudrate / 11 )
             *             = 11 * Ticks_per_1s / Baudrate
             *             = 220000 / Baudrate
             * The reload for t3.5 is 1.5 times this value and similary
             * for t3.5.
             */
            usTimerT35_50us = ( 7UL * 220000UL ) / ( 2UL * ulBaudRate );
        }
        if( xMBPortTimersInit( ( USHORT ) usTimerT35_50us ) != TRUE )
        {
            eStatus = MB_EPORTERR;
        }
				else if( xMBPortSerialInit( ucPort, ulBaudRate, 8, eParity ) != TRUE )
				{
					eStatus = MB_EPORTERR;
				}			
```