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I have a weird problem with the Pin Port-F pin4 (0x10) on PIC18F6520
Whatever the level (0 or 5v voltage) at the input
pin Port-F pin4, the state doesn't change in PortF register.
the bit b4 is always read as 0 .
I used several methods to read it, with Btfsc intruction
or with MOVF Portf,W and test bit b4 in wreg.
In TrisF the Pin is well declared as a input
The analog to digital converter is disabled, Full inputs in logic mode.
the comparator is also disabled.
I verified that all registers implicated are in the good state
with a ICD3 in Step by Step mode.
ADCON0,ADCON1,TRISF,PORTF,CMCON,CVRCON.
I also verified that tere is no short circuit on hardware.
If someone have an idea ?

What value have you set for ADCON1?

jt must be correct. You have ADCON1 lower nibble set to less than 0x06. Since this is the DEFAULT on this register you have to set ADCON1 to 0x06 or higher.

disremy wrote:The analog to digital converter is disabled.
Full inputs in logic mode.
the comparator in also idsabled.
I verified that all registers implicated are in the good state
with a ICD3 in mode Step by Step.
ADCON0,ADCON1,TRISF,PORTF,CMCON,CVRCON.
...

All this states that you THINK you have put the correct value into all of these registers.
As you still have a problem, it is a much better idea to show the actual values in the registers, and/or the code writing to them, so others can independently verify you have done it correctly.

The code is a input driver witch collect the state of several pins on several ports
An extract of the code :

Code: Select all

PIN_FD_BK    EQU     2        ;
PIN_VARDEF  EQU     4        ;

Variables :

INPUTS2      EQU     0x017D    ; Recopie avec mise en forme des entrees
INP_AUX4    EQU     0             ; Set Si Entree Auxiliaire 4 Active Defaut VAR
INP_AUX5    EQU     1             ; Set Si Entree Auxiliaire 5 Active FeedBack


Code:
            MOVLW   00010100B       ;
            MOVWF   TRISF               ;
            CLRF       CMCON            ; Utile Sur les Pic18 A Partir de 40 Broches
            CLRF       CVRCON           ;
;
            MOVLW   0x0F               ; Added code to desactivate the AD
            MOVWF   ADCON1          ; usually not required
            CLRF       ADCON0          ;
            LFSR       1,INPUTS2       ;
            CLRF       INDR1             ;
            LFSR       0,INPUTS         ;
            CLRF       INDR0             ;
;
            BTFSS    PORTE,IN_TOR2      ; Recopie Entree TOR Aux 1
            BSF        INDR0 ,INP_AUX1    ; Le Contact doit etre ferme
;
            BTFSS    PORTE,IN_TOR1      ; Recopie Entree TOR Aux 3
            BSF        INDR0 ,INP_AUX2    ; Le Contact doit etre ferme

            MOVF    PORTF,W                  ;                                   Doesn't work
            BTFSC   WREG ,PIN_VARDEF   ; Recopie Entree PIN_VARDEF       -    -

       ;     BTFSC   PORTF,PIN_VARDEF  ; Recopie Entree PIN_VARDEF   Doesn't work
       ;     BTFSC   PORTE,IN_TOR1       ; Recopie Entree TOR Aux 1     Work Well on PORTE
            BSF        INDR1 ,INP_AUX4      ; Le Contact doit etre Ouvert
;
;
            BTFSC   PORTF,PIN_FD_BK    ; Recopie Entree TOR Aux 4  Work Well !!
            BSF       INDR1 ,INP_AUX5     ; Le Contact doit etre ferme
;
;
            MOVLW   00001011B          ; Added code to restore good state for AD
            MOVWF   ADCON1              ;
            MOVLW   00000001B          ;    
            MOVWF   ADCON0              ;

Use the LATx registers for individual output pin manipulation!

I know that but it is a input problem, not ouput
I always use LATx to ouptut and Portx to input !!!

Sorry for the brain-fart.

Are you able to try a different chip to eliminate the possibility of a bad pin maybe due to ESD damage? When you pull the pin high is it hi-z or does it take significant current. Does the pin work as an output?

Thanks,
I made the test and I have the same behavior on another pic18F6520.
For Esd is a good idea but, the PortF-pin4 is driven by the photo transistor of an optocoupler ...
Several input and output of portF are protected by optocouplers
All other pin of portF work well wathever input or ouput mode.

The Phototransistor collector pin of the optocoupler is pull-up by a 22K resistor to ensure good voltage level on portf-pin4 (4,8V).