Problem With Code Terry Can you Help

SailerMan

I was working with Jonny Mac on some code He wrote and I am have a problem getting it to work correctly. I am attaching the code.

Everything runs fine until I Change the pins...

The Unaltered Code block...

Sio             PIN     RD.7  INPUT  TTL    ' I/O to host (10K pull-up)

M2Pwm           PIN     RC.2  OUTPUT
M2InA           PIN     RC.1  OUTPUT
M2InB           PIN     RC.0  OUTPUT

And now my changes to accomidate a circuit board I designed.

Sio             PIN     RD.7  INPUT  TTL    ' I/O to host (10K pull-up)

M2Pwm           PIN     RC.2  OUTPUT
M2InA           PIN     RD.1  OUTPUT
M2InB           PIN     RD.0  OUTPUT

We can't figure out why when M2InA and M2InB are changed to port D pins the program does not transmit serial properly.

Transmit:
  ASM
    MOV   FSR, #serial                          ' (2)
    TEST  txCount                               ' (1)   transmitting now?
    JZ    TX_Done                               ' (2/4) if txCount = 0, no
    DEC   txDivide                              ' (1)   update bit timer
    JNZ   TX_Done                               ' (2/4) time for new bit?
    MOV   txDivide, #Baud1x0                    ' (2)   yes, reload timer
    STC                                         ' (1)   set for stop bit
    RR    txHi                                  ' (1)   rotate TX buf
    RR    txLo                                  ' (1)
    DEC   txCount                               ' (1)   update the bit count
    MOV   W, #$0F                               ' (1)   read TRIS_A
    MOV   M, W                                  ' (1)
    MOV   !RD, W                                ' (1)
    MOV   tmpTris, W                            ' (1)   copy to tmpTris
    MOVB  tmpTris.7, txLo.6                     ' (4)   new bit to tris
    MOV   W, #$1F                               ' (1)   update TRIS_A
    MOV   M, W                                  ' (1)
    MOV   !RD, tmpTris                          ' (1)

TX_Done:
  ENDASM

Can you help?

JonnyMac

Terry,

I can vouch for this the program runs fine until you try to change the status of the RD.1 and RD.0 bits, and this makes absolutely no sense at all.

Peter Verkaik

I don't think the error is this

· PLP_C = %0000_0111
· PLP_D = %1000_0000

but port C and port D have different pullup settings on pins 0 and 1.

regards peter


Post Edited (Peter Verkaik) : 5/28/2009 7:09:54 AM GMT

Bean

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.

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

Bean.

P.S. "MOV !RD,tmpTris" is a 2 cycle instruction "MOV W,tmpTris", "MOV !RD,W"






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Post Edited (Bean (Hitt Consulting)) : 5/28/2009 12:31:29 PM GMT

JonnyMac

Okay, I think I get it now... when the Sio pin is in an input state (reading incoming serial) the output bit can RD.7 can be set to a "1" because of the pull-up and the stop bit ("1" in true mode). D'oh!

Eric, the version attached uses your original connections and I've verified that the code is now talking back (to a Stamp).

Post Edited (JonnyMac) : 5/28/2009 5:03:18 PM GMT

SailerMan

Bean,

Thanks.. for picking though out.

Jon,

Thanks for all of your help and your code. I'll be playing with this when I get home tonight.

Best Regards to Both,
Eric