In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bean wrote:

I'm not sure if this is the problem, but I suspect it is.

Try adding a "CLRB Sio" after the "MOV !RD,tmpTris" in the transmit routine.

Try this program below to show the cause of this problem.

 


[code]
DEVICE SX28, OSCXT1 
FREQ 10_000_000 
 

  

OUT1 PIN RB.0 OUTPUT PULLUP 
OUT2 PIN RB.1 OUTPUT PULLUP 

PROGRAM Start NOSTARTUP 
 

  

Start: 
  OUTPUT OUT1 ' Make OUT1 an output 
  OUT1 = 0 ' Set OUT1 output latch to low 
  INPUT OUT1 ' Make OUT1 an input (pullup will make OUT1 high) 
 

  

  OUT2 = 0 ' Here is what causes the problem. 
           ' To make OUT2 low, the controller reads the WHOLE port, when it does this OUT1 will read as high because of the pullup. 
           ' Now it sets the OUT2 bit to zero, and writes the WHOLE port back (this causes OUT1 output latch to be set to a 1) 
 

  

  OUTPUT OUT1 ' When we make OUT1 an output, it is high now. 
END 
[/code]
Bean.

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