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i need help for PIC16C745

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christina86

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Hi everybody,

I'm using the PIC16C745 microchip to do my final year project
I have encounter some problem.the situation is,
if switch 1 is pressed, LED will light up and when switch 2 is pressed again, the LED will go off. I am using an assembly language ( sofware MPLab version 7.2) to write the code.
I have succesffuly bulit the code to the PIC16C745 chip, but the led fail to on.
Here is my code :
MAIN org 00000030h

Start
clrf PORTB ; clear PORTB output latch
movlw b'00000000' ; Set all pins PORTB as output
MOVWF TRISB ;

ON
btfsc PORTA,4 ; Has S2 been press? (Normally high,goes low when pressed.)
goto ON ; No, go back check again
movlw b'00000001' ; move it from register 1 to w.
movwf PORTB ; move it to PORTB to light up the LED

OFF
btfsc PORTA,5 ; Has key been press? (Normally high, goes low when pressed.)
goto OFF ; No, check again
movlw b'00000000' ; move it from register 1 to w.
movwf PORTB ; OFF the LED

DebounceA
btfss PORTA,4 ; Has key been released?
goto DebounceA ; No, wait again
goto Start ; Loop again
end ; directive indicates end of code

Can anyone help me with the code weather i have done it correctly and how the circuit will look like ?

Thank you so much !
 

cameo_2007

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where have you confugured TRISA as input port?

And look,next time copy here the exact program what you have written in your work space.
 

christina86

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hi cameo_2007 : ) . Thank you so much for replying my post. Uhm, i have just made some amend to the code again. Here is the code :
MAIN org 00000030h

Start
bsf STATUS,RP0 ; select bank1
clrf PORTB ; clear PORTB output latch
movlw b'00000110' ; Set all pins PORTB 1,2 as Input
MOVWF TRISB ;

ON
btfsc PORTB,1 ; Has S2 been press? (Normally high,goes low when pressed.)
goto ON ; No, go back check again
movlw b'00000001' ; move it from register 1 to w.
movwf PORTB ; move it to PORTB to light up the LED

OFF
btfss PORTB,2 ; Has key been press? (Normally high, goes low when pressed.)
goto OFF ; No, check again
movlw b'00000000' ; move it from register 1 to w.
movwf PORTB ; OFF the LED

DebounceA
btfss PORTB,1 ; Has key been released?
goto DebounceA ; No, wait again
goto Start ; Loop again
end ; directive indicates end of code

I use only one port instead to be an input and output. When i build the code inside the PIC16C745, the Led still not turn on. Can you help me to see weather to code i have done correctly. Thank you
 

cameo_2007

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christina86 said:
OFF
btfss PORTB,2 ; Has key been press? (Normally high, goes low when pressed.)
goto OFF ; No, check again
movlw b'00000000' ; move it from register 1 to w.
movwf PORTB ; OFF the LED
you say it becomes low when the switch is presse,then u need to skip "goto OFF",if the bit is clear.rite?
i mean u need to use btfsc??
 

christina86

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Dear Cameo,

Thank you so mush for replying my post. I am totally new to this PIC16C745, i have got the project from my teacher which is totaly new to me, it is nothing related to my course of study. I am in the process of learning. Please give me your guidance.
I have made some changes to the code but it is still not working . Can you help me to check?
The code is :
MAIN org 00000030h

Start
bsf STATUS,RP0 ; select bank1
movlw b'00000110' ; Set pins PORTB 1,2 as Input
movwf TRISB ;
bcf STATUS, RP0 ; go back to Bank 0
ON
btfss PORTB,1 ; ( btfss mean it is set to *1* , they will skip to next instruction
goto ON ; No, go back check again
movlw b'00000001' ; move it from register 1 to w.
movwf PORTB ; move it to PORTB to light up the LED

OFF
btfss PORTB,2 ; Has key been press? (Normally high, goes low when pressed.)
goto OFF ; No, check again
movlw b'00000000' ; move it from register 1 to w.
movwf PORTB ; OFF the LED

end ; directive indicates end of code
Thank you so much . I look forward to hearing from you.
 

penoy_balut

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you have to continously scan the status of your port pins
 

cameo_2007

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christina86 said:
Dear Cameo,

btfss mean it is set to *1* , they will skip to next instruction
btfss means it will skip the very next instruction if th ebit is set 1

for eg:-
btfss PORTB,1
goto ON
movlw b'00000001'

if port B,1 is set "1", it will skip the line "goto ON". and will execute "movlw" instruction.
 

christina86

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Is that mean i do it wrong? Can you tell me wihch is the correct way of doing ? Cameo
 

cameo_2007

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christina86 said:
OFF
btfss PORTB,2
change that to btfsc,and try..still there cud be some more issues.
just check it this in the mean time,let me see the code again.
 

christina86

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thank you cameo, i will change it and see weather it works.
 

christina86

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hi Cameo.

i did change the like what you said . BUt the Led is not turning on.

myCOde is :
list p=16c745 ; list directive to define processor
#include <p16c745.inc> ; processor specific variable definitions

__CONFIG _H4_OSC&_WDT_OFF&_PWRTE_OFF&_CP_OFF
Errorlevel-302;

org 0x00000020

Start


bsf STATUS,RP0 ; select bank1
clrf PORTB ;clear PORTB output latch
clrf PORTA ;clear PORTA output latch
movlw b'00000000' ; Set pins as Output
movwf TRISB

movlw b'00000011' ; Set RA0 and RA1 as Input and the Rest is output
movwf TRISA
bcf STATUS,RP0 ; select bank0

ON
btfsc PORTA,0 ;Has S1 been press? (Normally high,goes low when pressed.)
goto ON
bsf PORTB,0 ;turn on RP0 (LED) only;


OFF
btfsc PORTA,1 ;Has S2 been press? (Normally high,goes low when pressed.)
goto OFF
bcf PORTB,0 ;turn off RP0 (LED) only;

goto Start
end

Can you help me
 

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