Hello All:
After 6 hours I am stumped....I can't get PORTB to behave normally. I have whittlerd down my prg to bare basics and still can't solve it.
Here is the code, nothing else is happening.
Code:
banksel ANSEL
clrf ANSELH
clrf ANSEL
banksel TRISA
clrf TRISB
clrf TRISA
bsf TRISB,4
test;
clrf STATUS
clrf PORTB
bsf PORTB,5; no go, port b5 remains low, seems to behave like an input , scoping the pin picks up noise if nearby pins switch.
movlw b'00100000'
movwf PORTB ;no go either ,but triggering PORTB5, B3 and B2 (b'00101100') will allow B5 to set. WHY????!!
goto $
The circuit is attached, although I don't see any interaction to cause this. I have changed the MCU already, both behave the same and both are new.
I did that as well, cleared T1CON. no change so took it off b4 I posted to keep it simple.
Hard to figure.
I am going to dismantle this circuit board slowly, isolating pin by pin, perhaps there is some type of electrical problem. Just guessing now.
EDIT: Well it was an elec. problem. A short on an RB5 pullup resistor bridging to RB2. But the short was apparently >50ohm which defeated the DMM continuity test, no beep. However it was enough to cause electrical interactions between RB2 & 5 so that unless they were both at the same state an indeterminate result could obtain on both of them.