pic first build test board not running

[Jumper]

Try to turn on only one (or all) at the same time and leave them on. Toggle pins on the same port rapidy after each other can give RMW (read modify write) problems when running the pic at 20 MHz.

So all on or one, but leave the blink blink for step 2

/me

[comwarrior]

here is the program i threw together in about 2 mins just for a test sequence...

Define  OSC				20
Define CONF_WORD = 0x3F72

ALLDIGITAL
TrisA	=	%00000000					'Set everything on port A as output
TrisB	=	%00000000					'Set everything on port B as output
TrisC	=	%00000000					'Set everything on port C as output
TrisD	=	%00000000					'Set everything on port D as output
TrisE	=	%00000000

main:
low 0
low 1
low 2
low 3
low 4
low 5
low 6
low 7

High 0
pause 500
Low 0
high 1
pause 500
low 1
high 2
pause 500
low 2
high 3
pause 500
low 3
high 4
pause 500
low 4
high 5
pause 500
low 5
high 6
pause 500
low 6
high 7
pause 500
Low 7
high 6
pause 500
low 6
high 5
pause 500
low 5
high 4
pause 500
low 4
high 3
pause 500
low 3
high 2
pause 500
low 2
high 1
pause 500
low 1

goto main
END

Reprogramming to turn all on and enter nop loop

[Melanie]

1. The 877A has multiple Ground and Power pins, make sure you have them all connected.

2. You did remember to do something meaningful with the MCLR pin?

3. Whilst you have defined OSC 20 for your program, you need to set HS OSC in the PIC Configuration Fuses. Whilst your program compiles wihout error, it didn't do much for the CONFIG Fuse settings for my programmer which remained at XT OSC.

4. I don't recall what the default Brown-Out is for that PIC (again my programmer reported it ENABLED by Default)... you might need to turn it OFF to run at 4.3v.

[comwarrior]

jumper:
I threw this code in and compiled it...

Define  OSC				20
Define CONF_WORD = 0x3F72

main:
TrisB	=	%00000000					'Set everything on port B as output
PORTB = 255
goto main

oshon pic simulator reports all LED's on port B light up...
again, nothing on my test board...

Mel:
I'm using WinPIC800 and JDM programmer...
I'm loading the program and then clicking on settings and selecting HS under OSC...
Please correct me if i've wrong, but i thaught the CONF_WORD set the OCS type?

Thanks

[comwarrior]

when i re-read the chip into an empty winpic800 with default fuse options it reads the program and fuse settings in which it the fuse setting and switched to HS... so, i'm 99% sure it's setting the chip to HS... unless you want to tell me diferent...

[sinoteq]

Defines must be in capital letters DEFINE OSC 20.

Make sure MCLR is pulled up to VDD.

Make sure BOR is off.

I would take away the Conf_Word and set the config manually in my programmer. Just to make sure it is the correct setting, I have never seen your way of using a Define this way.

[comwarrior]

it seems i have some sort of oscilator problem...

it could be a bad solder joint or something like that... but it once lit all 8 LED's and then once i disconnected the power it refused to work again...
so i rebuilt the circuit on a small piece of plugboard and used a salvaged 1.4MHz crystal... wouldn't mind so much, but the pair of 20MHz crystals i've got spacifically to do the job are brand new...
The second crystal is allready in my proper build board...

I don't need the timing acuracy of an xtal but the speed will be required, has anyone got a formula for using RC? or is that not advisable at such speeds?

Thanks to everyone