Hi all
I trying to build a receiver with a pass code, a simple one .
The transmitter sends the code , and the receiver has dip switches to put the code .
I stuck on dip switches, how to put data from the switches? please help
here is a part of the code ,where I need help .

receive
btfss PIR1,RCIF; check for received data
goto receive
movf RCREG,W
ANDLW 0x0F ; mask out 4 upper bits
CALL CHK
BTFSS STATUS, Z ;
GOTO receive; keep recieving
PASS
BSF PORTA,7 ; pass ok
GOTO PASS
;--------------------------------
CHK
XORLW B'00000101' ; PASSCODE
RETURN

How put data from from the switches to PASSCODE
I have the switches on PORTA 0,1,2,3
Thank you

 

There are plenty of examples out there for inputting data from key pad etc, check out Nigel Goodwin Tutorial for one.
Max.

 

There are plenty of examples out there for inputting data from key pad etc, check out Nigel Goodwin Tutorial for one.
Max.

Thank you , but I need help , can not figure it out . I think I am missing just a line .

 

movf PORTA, w
andlw 0x0F
movwf PASSCODE

 

movf PORTA, w
andlw 0x0F
movwf PASSCODE

thank you , maybe I didnt explain it correctly .
RCREG,W has 8 bit info , the first 4 is the pass code .
so I masked the 4 upper bits , and now I need to check if the code from transmitter match the dip switches on the receiver .
so I am using XOR instruction to check . the question is how to put data from the switches to this line XORLW B'0000xxxx ;

CHK
XORLW B'0000xxxx ; PASSCODE
RETURN

 

hi Gag,
Think what the Op code XORLW means,, literal ?

E

EDIT:
http://microcontrollerslab.com/pic-microcontroller-assembly-language/

 

The code I gave takes the input from the switches on RA3:RA0 and puts it in PASSCODE.

 

The code I gave takes the input from the switches on RA3:RA0 and puts it in PASSCODE.

how I XOR passcode with RCREG,W , to see if it matches ?

 

movf PASSCODE, w
xorwf RCREG, w

 

movf PASSCODE, w
xorwf RCREG, w

thanks I will try right now

Here is how I put it together , doesnt work ...

receive
btfss PIR1,RCIF; check for received data
goto receive
movf RCREG,W
ANDLW 0x0F ; mask out 4 upper bits
CALL CHK
xorwf RCREG,W
BTFSS STATUS, Z ;
GOTO receive; keep recieving
PASS
BSF PORTA,7 ; pass ok
GOTO PASS
;--------------------------------
CHK
movf PORTA, w; READ SWITCHES
andlw 0x0F
movwf PASSCODE
movf PASSCODE,W

RETURN

 

Delete the four marked lines and three new ones:

receive
btfss PIR1,RCIF; check for received data
goto receive
movf RCREG,W <= delete this line
ANDLW 0x0F ; mask out 4 upper bits <= delete this line
CALL CHK
xorwf RCREG,W <= delete this line

; add these lines
movf RCREG, w
andlw 0x0F
xorwf PASSCODE
;
BTFSS STATUS, Z ;
GOTO receive; keep recieving
PASS
BSF PORTA,7 ; pass ok
GOTO PASS
;--------------------------------
CHK
movf PORTA, w; READ SWITCHES
andlw 0x0F
movwf PASSCODE
movf PASSCODE,W <= delete this line

RETURN

 

hi Gag,
Think what the Op code XORLW means,, literal ?

E

EDIT:
http://microcontrollerslab.com/pic-microcontroller-assembly-language/

THANK YOU

AlbertHall
Thank you very much for help !
You gave me the idea , I modified your code and it did work .thanks again

Delete the four marked lines and three new ones:

receive
btfss PIR1,RCIF; check for received data
goto receive
movf RCREG,W <= delete this line
ANDLW 0x0F ; mask out 4 upper bits <= delete this line
CALL CHK
xorwf RCREG,W <= delete this line


; add these lines
movf RCREG, w
andlw 0x0F
xorwf PASSCODE
;
BTFSS STATUS, Z ;
GOTO receive; keep recieving
PASS
BSF PORTA,7 ; pass ok
GOTO PASS
;--------------------------------
CHK
movf PORTA, w; READ SWITCHES
andlw 0x0F
movwf PASSCODE
movf PASSCODE,W <= delete this line

RETURN

thanks I will try this part too

I tried this part and it works too .Great help, thanks

 

Now the tricky question. Do you understand why it didn't work and why it does now?

 

Now the tricky question. Do you understand why it didn't work and why it does now?

sure I do ,
when it didnt work , I modified it in my way , it did work too ,
but I think I am going to use your version .

I see you dont mind to help , some people here just point on Google search , which means no help