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Setting S0RIR

Elliot Chisholm

Hi,

After receiving a command on the serial port I want to disable all interrupts and then wait for the serial port to receive a byte. The following code shows what I am doing.

IEN = 0 ;
_nop_() ;
_nop_() ;

while( !S0RIR ) ;
rxbyte = ( uint8_t ) S0TBUF ;
S0RIR = 0 ;

It appears that I never pass the while loop. Does disabling the serial rx interrupt stop S0RIR being set ? Any ideas ?

I am using a ST10F168.

Cheers

Elliot

Parents
  • 0 in reply to Mik Kleshov 

    while( !S0RIR & !S0EIR ) ;
    ... can be confusing.

    And quite probably generates more code if efficiency is a concern. The only time you would want the bitwise-AND versus the logical-AND in this context is when you need the side effects of evaluating the second operand (which is extremely unlikely to be the case here).

Reply
  • 0 in reply to Mik Kleshov 

    while( !S0RIR & !S0EIR ) ;
    ... can be confusing.

    And quite probably generates more code if efficiency is a concern. The only time you would want the bitwise-AND versus the logical-AND in this context is when you need the side effects of evaluating the second operand (which is extremely unlikely to be the case here).

Children
  • 0 in reply to Dan Henry

    Hi Again

    This code works at 9600 baud but seems to have problems at higher rates and is contrary to the manual.

    uint8_t GetByte( void )
{
	uint8_t rx_char ;

	while( !S0EIR && !S0RIR ) ;

	rx_char = ( uint8_t ) S0RBUF ;
        S0RIR = 0 ;
	S0EIR = 0 ;

	return rx_char ;
}

    but this code cause a reset

    uint8_t GetByte( void )
{
	uint8_t rx_char ;

	while( !S0RIR ) ;

	rx_char = ( uint8_t ) S0RBUF ;
        S0RIR = 0 ;

	return rx_char ;
}

    I am not using a watchdog and have no interrupts. Has anyone any theories on what might be happening ? This is driving me mad.

    Cheers

    Elliot

  • 0 in reply to Elliot Chisholm

    Well, without an in-circuit debugger you can never be sure what's going on. Besides, hardware problems is always a possibility (floating NMI pin, for example.)
    Set up debugging with Monitor166. Even if there is no external RAM in your target hardware, you should be able to debug small pieces of code with 6Kbyte of XRAM.

    Good luck!
    - mike

  • 0 in reply to Mik Kleshov

    Servicing my non-running watchdog timer means that the code now works fine.

        while( !S0RIR )
    {
        _srvwdt_() ;
    }

    rx_char = ( uint8_t ) S0RBUF ;
    S0RIR = 0 ;
    Maybe a hardware problem ? Thanks for your help.

    Cheers


    Elliot

  • 0 in reply to Elliot Chisholm

    The watchdog timer is running unless you stop it before an EINIT or SRVWDT instruction.

    Sauli