Weird issue with Lab X1

[mackrackit]

Might want to turn LVP off, I do not think you are using it.

I keep going back to hat fancy OSC thing. The 877 is pretty straight forward. Has to be the OSC acting up to cause a change in speed. Power cycling causing a clitch? And somehow the programmer is resetting it?

[Demon]

LVP OFF is the first thing I tried, no diffference.

[Demon]

I unplug the USB cable to the programmer or disconnect the programmer completely from the Lab X1, touch the oscillator and the timing returns to normal speed!

Ok, so what can be the causes of something like this? This goes into capacitance stuff and that's over my head.

[mackrackit]

Being I just learned about that OSC and have not pulled the data sheet I do not know.

But...

I will make an assumption that this board was in storage since you say you have been out of this for awhile. Look for loose/broken connections and corrosion/tin whiskers.

Maybe put it under a heat lamp for a bit.

[Demon]

Can't see anything wrong with it. I emailed MeLabs support, hopefully they can figure this out.

I paid over $200 for this puppy, I finally get around to using it and it's acting funky.

At least the USB programmer was a nice step up from the serial programmer, but darn, this hobby doesn't come cheap.

[Acetronics2]

Hi, Robert

Could you verify which is your Osc setting ON THE CHIP by re-reading it ...

I suppose for some reason there's no CONFIG Writing and you run your default RC osc ...
( option to tick somewhere for programmer ??? - MPLAB Has ! )

For your Missing link to Antoon gadgets ...

just try this one : http://www.sentex.ca/~mec1995/index.htm ...

Alain

[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.

[Bruce]

Are you using your U2 USB programmer to power the Lab-X1?