PIC16F87 pins seem to be getting crossed over

[mackrackit]

If might help if you showed your code. Even if the code is not the problem

[The Master]

Ok, Ive made a really basic version to save you looking through hundreds of lines of code. It uses the power LED to show the output (inverted) and the status LED to show the value sent by serial. My laptop sends 1 and 0 alternately.

'^Define_Chip: PIC16F87

'Define the oscillator (20MHz)
DEFINE OSC 20

'Set the tris registers
TRISA=%00001000
TRISB=%11000101

CMCON=7
CVRCON=0
CCP1CON=0

'Serial port settings
RCSTA.7=1	'Enable the serial port
RCSTA.4=1	'Enable synchronous mode
TXSTA.5=1	'Enable transmit
TXSTA.2=1	'Enable high baud rate

'SPBRG=10	'Baud: 115200, Error: -1.36%
SPBRG=64	'Baud: 19200, Error: 0.16%

bTemp VAR BYTE

'Define output pins
pSmoke1 VAR PORTA.2
pSmoke2 VAR PORTA.4
pSmoke3 VAR PORTB.1
pSmoke4 VAR PORTB.3

pPower VAR PORTA.0
pStatus VAR PORTA.1

pData VAR PORTB.4	'Switches between Master and Slave

'Define input pins
iSmoke1 VAR PORTA.3
iSmoke2 VAR PORTB.0
iSmoke3 VAR PORTB.7
iSmoke4 VAR PORTB.6

'Check that input pins are set to inputs
INPUT iSmoke1
INPUT iSmoke2
INPUT iSmoke3
INPUT iSmoke4

'Make sure all of the outputs are off
LOW pSmoke1
LOW pSmoke2
LOW pSmoke3
LOW pSmoke4

LOW pPower
LOW pStatus

LOW pData

'BEGIN: Main loop
loop:
	
	'Check if serial data has arrived
	IF PIR1.5=1 THEN
		
		bTemp=RCREG
		
		pStatus=bTemp.0
	ENDIF
	
	pPower=~iSmoke4
GOTO loop

In this example grounding the input pin makes the power LED light up as expected. When i send the alternating serial values then the status LED toggles as it should. When ground the input _and_ send serial data then the status light never comes on. Something i didnt notice before is that if the status light is already on then grounding the input turns it off. That would suggest that the grounding causes a blank byte to appear in the UART buffer.

[Archangel]

PortB.6 has analog functions. You need to properly set your ADCON0, ADCON1, and ANSEL to turn those off for digital operation.

[The Master]

I tried that but i keep getting compile errors on all 3 lines saying "Symbol not previously defined"

Edit: Ive had a look in the datasheet and it seems they should exist. Im not sure why im getting an error. The correct chip is selected

[Melanie]

Just quickly tried to compile your example with v2.46 without error.

It would suggest that if these three lines...

CMCON=7
CVRCON=0
CCP1CON=0

...are causing you problems, then you have NOT got the correct chip selected somewhere...

And it goes to say that you have default Analog functions still enabled on your PIC.

It's always a good idea to EXPLICITY define the start of your program with the chips CONFIG parameters along with the chip you are using... example...

	@ DEVICE pic10F206, WDT_OFF
		' Watchdog Timer Disabled
	@ DEVICE pic10F206, MCLR_OFF
		' Master Clear Options Internal
	@ DEVICE pic10F206, PROTECT_OFF
		' Code Protection Disabled

...because if, further down the line, you inadvertantly start to compile for the wrong chip, you end up with a whole heap of errors pointing you to the fact that you've done something wrong (or have the wrong chip selected somewhere).

[The Master]

I never got the fuses to work from within the code. It seems like theres a few ways of doing it and i never found the right one. I did read an example somewhere that said to change an include file. Heres the line in that file

__config _CONFIG1, _HS_OSC & _WDT_OFF & _LVP_OFF & _CP_OFF


CMCON, CVRCON and CCP1CON are working fine. The 3 that dont work are ADCON0, ADCON1, and ANSEL. The datasheet says they should exist and i found them defined in PIC14EXT.BAS which aparently gets included for the PIC16F87. As you can see from my code the chip is defined correctly. That line gets picked up by an app i wrote that handles the compiling. Just to be on the safe side i went back to MCS and tried to compile as ive done in the past (16F87 is selected) and it still wont compile.

[Melanie]

The Datasheet is shared between the F87 and F88. Those Registers don't exist in the F87 (first paragraph of section 12).