HID USB on 18F87J50

[ScaleRobotics]

I didn't get very far on the Microchip forum. http://www.microchip.com/forums/tm.a...mpage=1#597082 They wanted me to try the simulator, and see if the simulator thought that should work or not. I couldn't get far enough in Mplab to find out. Though I am not sure how useful that would be. Does a simulator always sim what it should?

[mister_e]

MPSIM worked with PBP 2.x, will try with PBP3. It has to.

And NO a simulator do not always give you the good results, some are worst than others. As a guideline they are usually decent tool or pure toy, not much.

[Darrel Taylor]

What did you try in MPSIM?

I'm finding that it's reversed in MPSIM.
MOVFF and FSR's work, but banked instructions don't.

[mister_e]

I haven't tried this specific PIC yet. I try to stay away of Sims

[Darrel Taylor]

OK, I'm getting closer.
I think I can make USB work on it.

What a screwy chip.

[tumbleweed]

This is all very interesting. Care to share what you've been able to find out so far?

How is this chip different than the others?

[ScaleRobotics]

How is this chip different than the others?

I am sure Darrel will share more.

But one way it is a bit odd, is it shares addresses for SFR's. See: 5.3.5.1 Shared Address SFRs . You have to set the ADSHR bit in the WDTCON register to access the alternate locations.

[Darrel Taylor]

WOW, I've been chasing my tail, and apparently for not.

The MPASM that comes with MPLAB 8.73a was generating incorrect opcodes for the banked instructions.
This was making me think things were happening in the chip that should not have been happening.

The actual silicon in the xxJ50's is not the problem.

There is a new version MPLAB 8.76 which has fixed the errors.
Compile your USB programs using the new assembler, and walla, working USB.

There are other chips that will be affected by the problem, and it's not only USB that will be affected, so it is recommended that everyone with PBP 2.60 or later upgrade MPLAB to a version higher than 8.73a.

[pedja089]

I just recompile CDC from last attempt and it is working. Now just to try HID with VB6.
You save my butt, again

[pedja089]

Maybe is screwy, but it have everything I need for this project, and it's cheep. Thank you