Weird issue with Lab X1

[Charles_Leo]

Robert, do you have an oscilloscope or frequency probe to check the actual clock frequency that's being supplied to the chip? I would start there before pursuing config settings and include files. I wouldn't be surprised, though, if the frequency corrects the instant you touch the pin with a probe.

My gut feeling is that there is an open connection somewhere in the clock multiplier circuity. This could be as simple as a pin on the surface mount chip that was deprived of solder. This has happened occasionally (though not recently, to my knowledge) and all of the X1 boards are visually inspected for this. But... there is always the possibility that one slipped through.

A careful visual inspection with a magnifier might yield a clue. (Picture Sherlock Holmes.)

I received your email, but I wanted to address the issue of included header files publicly. This may help others understand PBP's compilation process.

PBP handles the inclusion of header files automatically. This is why you have to specify the target device when you compile. If you manually include files like 16F877.BAS, 16F877.INC, M16F87X.INC, or P16F877.INC, it will cause errors.

16F877.BAS is a PBP file that specifies memory map info, library files, etc.. It is also used to set up aliases for special compatibility, like PORTL/PORTH for BASIC Stamp. This file is created by melabs and it is always included.

16F877.INC is an Assembly file that holds default configuration fuse settings and specifies the header file for the assembler. If the device is supported by the PM Assembler, the file holds settings for PM and MPASM. Otherwise it holds only settings for MPASM. This file is created by melabs and it is always included.

Assembler header files hold the names and addresses of internal registers, configuration fuse information (including those mysterious labels that are used in config directives), and other stuff like bit names. Some of the MPASM header files are quite large.

M16F87X.INC is the header file for the PM Assembler. It is included automatically if the PM Assembler is used. melabs creates these files.

P16F877.INC is the header file for the MPASM Assembler. It is included automatically if MPASM is used. Microchip creates these files.

[Demon]

Robert, do you have an oscilloscope or frequency probe to check the actual clock frequency that's being supplied to the chip? I would start there before pursuing config settings and include files. I wouldn't be surprised, though, if the frequency corrects the instant you touch the pin with a probe.

My gut feeling is that there is an open connection somewhere in the clock multiplier circuity. This could be as simple as a pin on the surface mount chip that was deprived of solder. This has happened occasionally (though not recently, to my knowledge) and all of the X1 boards are visually inspected for this. But... there is always the possibility that one slipped through.

...

My oscilloscope is not on hand at the moment, and I suspect the same thing will happen.

I have a powerful magnifier somewhere, I'll have to dig it up and inspect the clock circuitry and report back.

Thanks for description of includes, that was pretty much what I had deducted as I fumbled along yesterday.

[Bruce]

It does sound like a bad connection/component in the osc circuit.

How does it act it you insert a long delay at power-up?

Say PAUSE 5000 (or longer) before turning any LEDs on?

[Demon]

I had tried with 3000, 5000 didn't make a difference either.

So I flipped the X1 over (now looking at solder side, LCD at the top end):

- touched the oscillator lead tip on the right, no difference.
- touched the oscillator lead tip on the left, blinking returned to normal pace.

[mackrackit]

Now you know where to use the soldering iron.

[Demon]

Didn't help (didn't have time to try anything else though).

I'm going to dab the legs on the timer IC even if they all look nice and clean. I doubt it will work but I have nothing to lose.

If that doesn't work I'm thinking that maybe the hole for the OSC is not done right, maybe it was supposed to be a via but no signal is going to the top layer.

I'm going to try to remove that 4MHz osc and check the inside of the hole (and continuity if there are pads on both sides). Then solder another one back with longer legs so I can solder both top and bottom.

After that I don't know what else to do except take it skeet shooting next time out.