digital input for pic16f877 on PORT A

pic16f877 porta

hi there..
could anyone help me with my problem ....
im trying to send data on port A of pic16f877
but nothing happens... here is my sample code....



list p=16f877
#include <p16f877.inc>


__CONFIG _CP_OFF & _WDT_OFF & _BODEN_ON & _PWRTE_ON & _XT_OSC & _WRT_ENABLE_ON & _LVP_ON & _DEBUG_OFF & _CPD_OFF






ORG 0x00



start


CLRW


BSF STATUS, RP0


MOVLW 0x06
MOVWF ADCON1
MOVLW 0X00
movwf trisa
BCF STATUS, RP0


LOOP

MOVLW 0XFF
MOVWF PORTA
nop
nop
nop
nop
nop
nop
nop
nop
nop
nop
nop
nop
movlw 0x00
movwf porta
GOTO LOOP
END

..... this is just a simple blinking of the led... just to see if i could really send data to port A

pic16f877 adcon1 digital io

yllongboy said:

hi there..
could anyone help me with my problem ....
im trying to send data on port A of pic16f877
but nothing happens... here is my sample code....

list p=16f877
#include <p16f877.inc>

__CONFIG _CP_OFF & _WDT_OFF & _BODEN_ON & _PWRTE_ON & _XT_OSC & _WRT_ENABLE_ON & _LVP_ON & _DEBUG_OFF & _CPD_OFF

ORG 0x00

start


CLRW


BSF STATUS, RP0


MOVLW 0x06
MOVWF ADCON1
MOVLW 0X00
movwf trisa
BCF STATUS, RP0


LOOP

MOVLW 0XFF
MOVWF PORTA
nop
nop
nop
nop
nop
nop
nop
nop
nop
nop
nop
nop
movlw 0x00
movwf porta
GOTO LOOP
END

Click to expand...

bsf STATUS,RP0 ;set to Bank 1
MOVLF B'00000111',ADCON1 ;setting all AD pins to digital I/O
clrf TRISA ;setting all port a to output


also look at the word start
see others structs to follow namings although it may work its not good practice


also

HS osc is to enable HIGH SPEED crystal >4mhz so if your using
a crystal it will sit and do nothing
__CONFIG _CP_OFF & _WDT_OFF & _BODEN_ON & _PWRTE_ON & _HS_OSC & _WRT_ENABLE_ON & _LVP_ON & _DEBUG_OFF & _CPD_OFF

dont forget to add +5v via a 10k res to the mclr pin or the chip wont boot



**broken link removed**

pic16f877a porta

thank you for the posted rply.....
.... i already followed all the instructions above and it seems that it is still not working.... i could not get any output from port A so as all other ports...
... could somebody help me solve my problem. It would be better if there would be a sample running circuit..
...
thank you...

port 16f877 a-e

Hi,
I think you should try by keeping lvp off if you are note using it .

according to your code off time for yor led is only two or three instruction cycles at 4mhz it amounts to 3 micro seconds. I gus you need atleast 250milliseconds on off time to see a flashing led.
Thanks

adcon1 16f877

yllongboy said:

thank you for the posted rply.....
.... i already followed all the instructions above and it seems that it is still not working.... i could not get any output from port A so as all other ports...
... could somebody help me solve my problem. It would be better if there would be a sample running circuit..
...
thank you...

Click to expand...

http://www.piclist.com/techref/microchip/16F877/flashled.htm

using porta of pic16f877

hi,
If you are using 16F877A all the ports will be in input mode.
you have to change it in out put mode , otherwise your pic may damage.
there are four problems I found in your code.

1, when you are using LVP_ON you have to pull down LVP pin
2, tris command should be in capital letter TRISA
3, port command also should in capital PORTA
4, use some noticable delay between changing ports so that you can identify.

Note: TRY PORTB OR PORTC FIRST THEN MOVE TO PORTA

TRY THIS CODE

good luck

how can set adcon1 to digital input in pic16f877a

thanks for the rply.. can i have a circuit on this one.. i already tried it but it seems that my circuit doesnt work... i think my problem now is on the hardware side..
could anyone post a circuit..
thanks..