Hello,

I have been trying to get the flashing led example to work. While I got
things to work successfully (fairly painlessly) with a 16F628, I can not
gotten it to work with a 16F877.. I have a 9V power supply going into a
7805 voltage regulator, producing 5V @ ~200mA (is this ok? the data sheet lists
the high sink / source current as 25 mA..), the positive pin on the 7805
is connected to pins 11 and 32, and ground is connected to 12, and 31 on
the 16F877, and vdd is connected via a 100k resistor to pin 1 (MCLR) (I
tried it without connecting vdd to pin 1 also)... I put a led between rb0
(and rb1) and ground (and tried it with a resistor also), and used
several different programs including:

        LIST    p=16F877                ;tell assembler what chip we are using
        include "P16F877.inc"           ;include the defaults for the chip
        org     0x0000                  ;org sets the origin, 0x0000 for
the 16F628,

        CBLOCK 0x20
Pause_H
Pause_M
Pause_L
        ENDC
                                        ;this is where the program starts running
        movlw   0x07
        movwf   ADCON1                  ;turn off a/d.. also tried without this

        bsf     STATUS,         RP0     ;select bank 1
        movlw   b'00000000'             ;set PortB all outputs
        movwf   TRISB
        movwf   TRISA                   ;set PortA all outputs
        bcf     STATUS,         RP0     ;select bank 0

Led_Loop
        call    OFF
        call    PAUSE
        call    ON
        call    PAUSE
        goto    Led_Loop

ON
        movlw b'00000001'       ; RB0 = on, RB1 = off
        movwf PORTB
        return
;
; LED OFF SUBROUTINE
;
OFF
        movlw b'00000010'       ; RB0 = off, RB1 = on
        movwf PORTB
        return
;
; TIME DELAY SUBROUTINE
;
PAUSE
        clrf Pause_L
        clrf Pause_M
        movlw 3h        ; changing Pause_H, means a coarse
        movwf Pause_H   ; change in time delay
P_Loop  decfsz Pause_L
        goto P_Loop
        decfsz Pause_M
        goto P_Loop
        decfsz Pause_H
        goto P_Loop
        return
        end


I have also tried a really simple program that just movlw b'00000001' to
PORTB and loops over and over, which doesn't light up the led either. I
checked to make sure the led was connected the right way also.

If anyone could point out anything obvious, that would be great!

Also, the config bits are set as follows:
oscillator: rc
watchdog timer: off
power up timer: on
brown out detect: on
low voltage program: disabled
flash program write: enabled
background debug: disabled
Data EE Read Protect: Off
Code Protect: off

I also tried it with watchdog timer on, and/or brown out detect off, power
up timer off..

Nathan

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