Can some one help me solve this as i am banging my head ,its just a simple 1hz led flasher on pin RA0,

i have built the asm file, programmed it and put the pic in the circuit board, all that happens is all the pins are at 2v op,with 2.6v ac signal , except the supply pins at 5volts .

Is there some thing in the programme i have done wrong or are my pics faulty??

;This is to flash an led on pin ra0 at 1hz



LIST p=16F88 ;tell assembler what chip we are using
#include <P16F88.inc> ;include the defaults for the chip
;set up config register

__CONFIG _CONFIG1, _CP_OFF & _CCP1_RB0 & _DEBUG_OFF & _WRT_PROTECT_OFF & _CPD_OFF & _LVP_OFF & _BODEN_OFF & _MCLR_OFF & _PWRTE_ON & _WDT_OFF & _INTRC_IO
__CONFIG _CONFIG2, _IESO_OFF & _FCMEN_OFF

org 0x0000 ;org sets the origin, 0x0000 for the 16F88,
;this is where the program starts running
goto Loop

cblock 0x20
d1
d2
d3
endc
bsf STATUS, RP0 ;select bank 1
movlw b'01110110' ;set osc to 8mhz
movwf OSCCON
movlw b'11000110' ;set up prescaler to 128 on Tmr0
movwf OPTION_REG

movlw b'00000000' ;set PortA all outputs
movwf TRISA
movlw b'11111111'
movwf TRISB ;set PortB all inputs
bcf STATUS, RP0 ;select bank 0
clrf PORTA ;clear portA
clrf PORTB

Loop
bsf PORTA,0
;set bit 0 on
call Delay
;
bcf PORTA,0
call Delay ;set bit0 off
goto Loop ;go back and do it again
Delay

;delay of 500msec at 8mhz clock
;999997 cycles
movlw 0x08
movwf d1
movlw 0x2F
movwf d2
movlw 0x03
movwf d3
Delay_0
decfsz d1, f
goto $+2
decfsz d2, f
goto $+2
decfsz d3, f
goto Delay_0
;3 cycles
goto $+1
nop

return
end

 

You need to write 00h to ANSEL to make it a digital port.
From 5.1 in the data book:

BANKSEL ANSEL ; Select Bank of ANSEL
MOVLW 0x00 ; Configure all pins
MOVWF ANSEL ; as digital inputs

 

Even this simple bit wont work, all it does it put led on portB 4& 5

all i get is 2v dc on the pins except the supply which is at 5v.


LIST p=16F88 ; list directive to define processor
#INCLUDE <P16F88.INC> ; processor specific variable definitions
;------------------------------------------------------------------------------
;
; CONFIGURATION WORD SETUP
;
; The 'CONFIG' directive is used to embed the configuration word within the
; .asm file. The lables following the directive are located in the respective
; .inc file. See the data sheet for additional information on configuration
; word settings.
;
;------------------------------------------------------------------------------
__CONFIG _CONFIG1, _CP_OFF & _CCP1_RB0 & _DEBUG_OFF & _WRT_PROTECT_OFF & _CPD_OFF & _LVP_OFF & _BODEN_OFF & _MCLR_ON & _PWRTE_ON & _WDT_OFF & _INTRC_IO
__CONFIG _CONFIG2, _IESO_OFF & _FCMEN_OFF
;------------------------------------------------------------------------------
;

RESET ORG 0x0000 ; processor reset vector
PAGESEL START
GOTO START ; go to beginning of program

bsf STATUS, RP0 ;select bank 1


movlw 0x0
movwf TRISB ;set PortB all outputs
bcf STATUS, RP0 ;select bank 0

;------------------------------------------------------------------------------
; USER INTERRUPT SERVICE ROUTINE GOES HERE
;------------------------------------------------------------------------------

;------------------------------------------------------------------------------
; MAIN PROGRAM
;------------------------------------------------------------------------------
START

bsf PORTB,4
bsf PORTB,5
END

 

You need a loop to stop the processor from continuing to run through the rest of program memory, which may be blank, or contain part of a previous program. After a short period it will probably be back at the start of program memory again. The END statement does not stop the processor.

 

I cant even get an output to go high on any port A or B so what is wrong in the setup??

 

This one has MCLR_ON, have you put a 10K resistor from the MCLR pin to 5V?

 

I don't think you have mentioned what type of programmer you are using. Some may require you to put the configuration in the uploading program. If you are programming by ICSP then the default setting may be to hold the device in reset. A picture of the setup might help us find the problem.

 

I am using a pickit2, and have never used it before so i dont even know if its working correctly, if you have an asm file that i can try for the 16f88 , just to make an led come on, any port will do so i can see if its the programmer,
as i'm loosing the will to live!!

 

As Markd77 says, you have to pullup the MCLR pin.
Can you post a circuit schematic?

 

If it says "verified OK" or something like that then it's working fine.
I haven't got any F88 test files.
How are you connecting the programmer and powering the PIC?
I'd suggest for now, programming, then removing the programmer and powering the PIC with a decent power supply. 3 AA batteries is a good supply.
I'm going to be unavailable for a couple of hours.

 

I have fixed the problem, it was the pics, so binned them, and gone onto the 16f628a and all is well and flashing ...