Problems with RC2 and RC3

[Christopher4187]

Hi,

I am using a program on a 16F870 where all pins are outputs with the exception of portc.7. I can activate each output one by one and turn them off with no problems. When I try to activate portc.2 and portc.3 with all other outputs active, they only turn others off and I can't understand why. Said differntly, they work fine by themselves but when combined with other outputs, the operation is not what was expected. Can anyone shed some light on this?

[sougata]

Hi,

Please post the code otherwise it is difficult to understand your exact problem.

[Christopher4187]

Ok, I don't like to post the code because it's not written very well and I am not an expert but maybe someone can help me. Here is the code:

@ DEVICE PIC16F870, HS_OSC, WDT_OFF, PWRT_ON, BOD_ON, LVP_OFF , DEBUG_OFF, PROTECT_OFF

DEFINE OSC 20
DEFINE HSER_BAUD 2400
DEFINE HSER_RCSTA 90h
DEFINE HSER_TXSTA 20h
DEFINE HSER_CLROERR 1
ADCON1=7
b1 var WORD 'first of 4 vars to store verified good data
b2 var WORD
b3 var WORD
b4 var WORD
in1 var WORD 'first of 4 vars to store incoming data
in2 var WORD
in3 var WORD
in4 var WORD
start var byte 'first incoming byte - should be zero
sum var WORD 'incoming checksum from the sending PIC
datasum var WORD 'used to add values of 4 incoming data bytes
errorflag var bit 'flag to indicate bad data (1 = bad or untested data)


TRISA = %00000000
TRISC = %10000000
TRISB = %00000000
TRISD = %00000000
pause 100

PORTB.0=0
PORTB.1=0
PORTB.2=0
PORTB.3=0
PORTB.4=0
PORTB.5=0
PORTB.6=0
PORTB.7=0
PORTA.0=0
PORTA.1=0
PORTA.2=0
PORTA.3=0
PORTA.4=0
PORTA.5=0
PORTA.6=0
PORTA.7=0
PORTC.0=0
PORTC.1=0
PORTC.2=0
PORTC.3=0
PORTC.4=0
PORTC.5=0
PORTC.6=0






mainloop:
IF RCSTA.1 = 1 THEN 'if USART overrun error flag OERR is set...
RCSTA.4 = 0 'clear and then set CREN bit to recover
RCSTA.4 = 1
in1 = RCREG 'read data to clear out RCREG
IF PIR1.5 = 1 THEN in1 = RCREG 'clear possible 2nd byte in RCREG
ENDIF

WHILE PIR1.5 = 0 'stay here until USART receives data

'LOW portc.3 'portc.3 has diagnostic LED
WEND


'HIGH portc.3 'data in RCREG; turn on diagnostic LED

errorflag = 1
GOSUB getdata

IF errorflag = 0 THEN 'only updates relays if data judged to be good


if b1=0 and b2=1 and b3=11 THEN GOSUB ONN1
if b1=0 and b2=1 and b3=12 THEN GOSUB OFF1
if b1=0 and b2=2 and b3=11 THEN GOSUB ONN2
if b1=0 and b2=2 and b3=12 THEN GOSUB OFF2
if b1=0 and b2=3 and b3=11 THEN GOSUB ONN4
if b1=0 and b2=3 and b3=12 THEN GOSUB OFF4
if b1=0 and b2=4 and b3=11 THEN GOSUB ONN3
if b1=0 and b2=4 and b3=12 THEN GOSUB OFF3
if b1=0 and b2=5 and b3=11 THEN GOSUB ONN5
if b1=0 and b2=5 and b3=12 THEN GOSUB OFF5
if b1=0 and b2=6 and b3=11 THEN GOSUB ONN6
if b1=0 and b2=6 and b3=12 THEN GOSUB OFF6
if b1=0 and b2=7 and b3=11 THEN GOSUB ONN7
if b1=0 and b2=7 and b3=12 THEN GOSUB OFF7
if b1=0 and b2=8 and b3=11 THEN GOSUB ONN8
if b1=0 and b2=8 and b3=12 THEN GOSUB OFF8
if b1=0 and b2=9 and b3=11 THEN GOSUB ONN0
if b1=0 and b2=9 and b3=12 THEN GOSUB OFF0
if b1=1 and b2=0 and b3=11 THEN GOSUB ONN9
if b1=1 and b2=0 and b3=12 THEN GOSUB OFF9
if b1=1 and b2=1 and b3=11 THEN GOSUB ONN11
if b1=1 and b2=1 and b3=12 THEN GOSUB OFF11
if b1=1 and b2=2 and b3=11 THEN GOSUB ONN13
if b1=1 and b2=2 and b3=12 THEN GOSUB OFF13
if b1=1 and b2=3 and b3=11 THEN GOSUB ONN12
if b1=1 and b2=3 and b3=12 THEN GOSUB OFF12
if b1=1 and b2=4 and b3=11 THEN GOSUB ONN14
if b1=1 and b2=4 and b3=12 THEN GOSUB OFF14
if b1=1 and b2=5 and b3=11 THEN GOSUB ONN16
if b1=1 and b2=5 and b3=12 THEN GOSUB OFF16
if b1=1 and b2=6 and b3=11 THEN GOSUB ONN15
if b1=1 and b2=6 and b3=12 THEN GOSUB OFF15
if b1=9 and b2=9 and b3=11 then gosub allon
if b1=9 and b2=9 and b3=12 then gosub alloff
ENDIF

goto mainloop:


getdata:
IF RCSTA.1 = 1 THEN xfer 'USART overflow error - bad data
HSERIN 40, xfer, [start, in1, in2, in3, sum]
IF start <> 0 THEN xfer 'if first byte isn't 0 assume bad data
datasum = in1 + in2 + in3 'add the 4 bytes and compare to sum
IF datasum = sum THEN errorflag = 0 'if compare is good, assume good data
xfer:
IF errorflag = 0 THEN
B1 = in1
b2 = in2
b3 = in3


ENDIF
RETURN

ONN1:
HIGH PORTB.7
goto mainloop
OFF1:
LOW PORTB.7
GOTO MAINLOOP

ONN2:
HIGH PORTB.3
goto mainloop
OFF2:
LOW PORTB.3
GOTO MAINLOOP

ONN3:
HIGH PORTB.4
goto mainloop
OFF3:
LOW PORTB.4
GOTO MAINLOOP

ONN4:
HIGH PORTA.3
goto mainloop
OFF4:
LOW PORTA.3
GOTO MAINLOOP

ONN5:
HIGH PORTB.5
goto mainloop
OFF5:
LOW PORTB.5
GOTO MAINLOOP

ONN6:
HIGH PORTA.2
goto mainloop
OFF6:
LOW PORTA.2
GOTO MAINLOOP

ONN7:
HIGH PORTC.2
goto mainloop
OFF7:
LOW PORTC.2
GOTO MAINLOOP

ONN8:
HIGH PORTC.3
goto mainloop
OFF8:
LOW PORTC.3
GOTO MAINLOOP:

ONN9:
HIGH PORTC.1
GOTO MAINLOOP
OFF9:
LOW PORTC.1
goto mainloop

ONN0:
HIGH PORTC.0
GOTO MAINLOOP
OFF0:
LOW PORTC.0
goto mainloop

ONN11:
HIGH PORTA.5
GOTO MAINLOOP
OFF11:
LOW PORTA.5
goto mainloop

ONN12:
HIGH PORTB.1
GOTO MAINLOOP
OFF12:
LOW PORTB.1
goto mainloop

ONN13:
HIGH PORTB.0
GOTO MAINLOOP
OFF13:
LOW PORTB.0
goto mainloop

ONN14:
HIGH PORTC.5
GOTO MAINLOOP
OFF14:
LOW PORTC.5
goto mainloop

ONN15:
HIGH PORTB.2
GOTO MAINLOOP
OFF15:
LOW PORTB.2
goto mainloop

ONN16:
HIGH PORTC.4
GOTO MAINLOOP
OFF16:
LOW PORTC.4
goto mainloop

alloff:
LOW PORTA.2
LOW portc.4
LOW portb.2
LOW portc.5
LOW portb.0
LOW portb.1
LOW PORTB.5
LOW porta.5
LOW portc.0
LOW portc.1
LOW portc.2
LOW portc.3
LOW porta.3
LOW portb.3
LOW portb.4
LOW portb.7
goto mainloop

allon:

PORTB.0=1
PORTB.1=1
PORTB.2=1
PORTB.3=1
PORTB.4=1
PORTB.5=1
PORTB.6=1
PORTB.7=1
PORTA.0=1
PORTA.1=1
PORTA.2=1
PORTA.3=1
PORTA.4=1
PORTA.5=1
PORTA.6=1
PORTA.7=1
PORTC.0=1
PORTC.1=1
PORTC.2=1
PORTC.3=1
PORTC.4=1
PORTC.5=1
PORTC.6=1

goto mainloop

[mister_e]

O.k, there's few thing to be removed first..


mainloop:
IF RCSTA.1 = 1 THEN 'if USART overrun error flag OERR is set...
RCSTA.4 = 0 'clear and then set CREN bit to recover
RCSTA.4 = 1
in1 = RCREG 'read data to clear out RCREG
IF PIR1.5 = 1 THEN in1 = RCREG 'clear possible 2nd byte in RCREG
ENDIF


DEFINE HSER_CLROERR 1 do this for you. Remove those line.



WHILE PIR1.5 = 0 'stay here until USART receives data
'LOW portc.3 'portc.3 has diagnostic LED
WEND

'HIGH portc.3 'data in RCREG; turn on diagnostic LED


While your program do nothing usefull there, simply remove those line and replace it simply for HSERIN.



if b1=0 and b2=1 and b3=11 THEN GOSUB ONN1
.
.
.


Should be writen like..


if (b1=0) and (b2=1) and (b3=11) THEN GOSUB ONN1




ONN1:
HIGH PORTB.7
goto mainloop


You jump to ONN1 with a gosub, it must be terminated with a RETURN to avoid stack overflow. Replace GOTO MAINLOOP by a simple RETURN.

Multiple PORTA.0=0, PORTA.1=0, ... can be replace with a single line. In your example you set all PORTA bit to zero. It's working sure, but you can still use PORTA=0. Same for all PORTx to 1. Can be replace with PORTx=%11111111, PORTx=$FF or PORTx=255.

Personnaly i would change it to something different..., let's try something.


TRISA = %00000000
TRISB = %00000000
TRISC = %10000000
ADCON1 = 7

PORTx var byte
PORTbit var byte
BitState var byte

PORTA = 0
PORTB = 0
PORTC = 0

mainloop:
hserin 500,mainloop,[PORTx,DEC1 portbit, DEC1 bitstate]
select case portx
case "A"
PORTA.0(PORTBIT)=BITSTATE
CASE "B"
PORTB.0(PORTBIT)=BITSTATE
CASE "C"
PORTC.0(PORTBIT)=BITSTATE
END SELECT
GOTO MAINLOOP

With few chunk around it may be something to play with

EDIT: also, there's no PORTD on the F870.. no warning or error using PM? I don't know how it's handle by PM but for sure, this will return you an error message when using MPASM...

@Darrel,
Yet another reason :D

[Christopher4187]

I have experimented more with trying to have all outputs on at the same time. Configured different ways, I have problems with portc.0, portc.1, portc.2 and portc.3. Has anyone ever tried to activate all ports on a 16F870, 876, 876A and been able to do it. Like I said, one by one they work fine but when I turn on all ports, I have difficulties with the ones mentioned above. I have tried 10 different PIC's so I am pretty sure it's not a hardware problem, there must be something in the software that needs to be changed.

Chris

[paul borgmeier]

What do you have connected to your port pins (e.g., LEDs, floating, etc.)?

Have you tried something like this to test PORTC?

For X = 0 to 255
PORTC = X
Pause 500
NEXT X

Paul Borgmeier
Salt Lake City, Utah
USA

[Christopher4187]

That works. The problem is when you have all ports activated (porta, portb, portc), there are issues with only portc. Like I said before, all outputs work on portc by themselves but when combines with other outputs, portc.0 through portc.3 has problems. Any more suggestions? Can someone else try to activate all ports on a 16F870, 876, 876A and see if it works?

Thanks,

Chris

[mister_e]

maybe you reach the maximum current source of your PIC. How about if you trade your LEDs to 1-10K resistors???

[Christopher4187]

The outputs are going to a ULN2003A and while I haven't measured it, the datasheet for the ULN2003A says it requires 1.2mA per pin.....this is well below the 200mA maximum by the PIC. The PIC is supplying roughly 19.2mA to activate the outputs.

[paul borgmeier]

...Like I said before, all outputs work on portc by themselves but when combines with other outputs, portc.0 through portc.3 has problems.

Call me slow, but I still do not understand. My suggested code in post #6 does activate combined pins of PORTC. If that worked, then I would try this:

PORTA = 255
pause 1000
PORTB = 255
pause
For X = 0 to 15
PORTC = X
Pause 100
NEXT X
Pause 10000
end

and see if it is still weird.

I was suspecting R-M-W issues as hinted in my subject line of post #6. Your code is full of R-M-W opportunity where the code above is not. If you still get weird results, you can rule out R-M-W issues. If your problem goes away, then it could be R-M-W.

My question about what you had connected was exactly where Steve went – possibly to much current but it seems you have ruled that out.

Paul Borgmeier
Salt Lake City, Utah
USA

[Christopher4187]

Paul,

I have located something abnormal. I took off all of the ULN2003A's from the board and I can get all of the outputs activated at the same time. Maybe current is the issue but it will require further investigation to determine where the problem exactly is.

Thanks,

Chris

[Christopher4187]

I have located the problem. On the ULN2003A (the one for PORTC), the negative pin was not soldered.....I must have overlooked it. When the ULN was trying to draw more current, it wasn't able to because of the high resistance between ground and the negative pin. Thanks to all who helped.

Chris