Hi,
I have a pic18F4520 in one application with the porta configured as:

clrf PORTA
clrf LATA
movlw    0x07
movwf    ADCON1        ; Disable analog inputs and
movwf    CMCON        ; comparators
movlw    b'11000000'    ; All outputs
movwf    TRISA

The pic is connected to a xc95144 cpld with all inputs in high impedance. The cpld is not affecting the pic because I removed it to check.

Now, when I set up porta,2  everything is OK, when I set up porta,3 the pin RA3 goes high, but for no reasons RA2 resets!
bsf        PORTA,2            ; set pin RA2, "this works OK"
bsf        PORTA,3            ; set pin RA3,  "this also works OK, but RA2 gets reseted!"

If I invert the order, that is RA3 and then RA2, the result is the same. If I write to both at once then everything is OK, but I don't want to do that because I would have to read the port first and save the contents.

movlw   b'11110100'    ; set pin RA2 only
movwf    PORTA
movlw    b'11111100'    ; now, set pin RA3 and keep RA2 high fro previous state
movwf    PORTA            ; This works, most likely because I'm updating the complete contents of the port.

I remember many years ago I read somewhere about inadvertently changing port contents, but I can't remember where. This most probably is some stupid mistake I'm doing, but I don't seem to catch it up. Any ideas?


      
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