Andy Jancura wrote:

> >O.K. So I'm reading the "B" version note,
> >Where is the "A" note?
> >Who has "B" version chips, and what do I have since I bought them months
> >ago
> >and they have neither A or B markings.
>
> Thomas, chip versions A,B etc. are usual used as marks for new chip layout,
> redesign or technology. They are marked on the chip package, like 16F84 and
> 16F84A. So far I know, at the time are available only the first versions of
> 18Cxx2.
>

DigiKey now says they have the "A" version.

>
> Errata sheets revision A,B are written after chip testing, both HW and SW.
> And all errors are then reported with possible corrections and work around.
> Let see the Atmel AVR errata, for some chips you find versions F,G,H and so.
> The last one contains summary of all previous.
>
> ...
>
> >I have discovered if you have in interrupt happen while using a MOVFF,
> >It may NOT complete the 2 part of the instruction,  and when you return
> >from interrupt
> >You get bogus results...
>
> Probably if more interrupts running simultaneously, one with higher priority
> as the other one.
>

Not at all!  I'm using 16C compatability, ONE level of interrupt.

> >
> >As Murphy would have it, I'm doing table lookups for a JUMP table and the
> >PC get some
> >pseudo-random value!
> >No, I'm not using MOVFF something, PCL.  That's been pointed out as a
> >no-no.
> >I am using MOVFF something, WREG, which is specifically encouraged in the
> >MOVFF
> >instruction manual.  Well the value in WREG get clobbered by interupts...
> >sometimes.
>
> I think MOVFF fs, fd is primary used for data exchange between two registers
> without affecting any status bits. This is usual needed  when you need to
> transfer some variables to locals and so. Not to transfer to W register.

From the manual!

"Either source or destination can be WREG..."

>
> When you need data to be in W reg. you must use the usual way with
>
> MOVF fs,W,source_bank
>
> If jump table is needed you cann't use MOVFF for this jumping, expect the
> case of fixed address stored in ram:
>
> Pointer_High, Pointer_Low - targed 16 bit address where to jump stored in
> ram
>
> MOVFF Pointer_High, PCLATH - this transfers only 8 bit from Pointer_High
> MOVF  Pointer_Low,W,bank_sel - cann't use PCL, then get it via W
> MOVWF PCL,bank_0 - jump
>
> If your addresses are in Program Space, you must use the TBLRD instructionin
> to get the 8 data
>
> set TBLPTR to point to adress of jump
>
> TBLRD*+
> MOVFF TBLATH, PCLATH

AND this is where it FAILS!!!
If you get an interrupt at this instruction, it will NOT complete correctly.

>
> TBLRD*
> MOVF TBLATH,W,bank_0 - again cann't use PCL as target in movff
> MOVWF PCL,bank_0
>
> >I didn't trust the RETFIE FAST to restore W, so I added my own
> >save/restore in the
> >interrupt service routine.  Didn't help either way.
>
> Did you tried to run with only one interrupt and correct disabled all other.
> Then did you setup the interrupt compatibility mode bit?
>
> Andrej
>
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  |  __O    Thomas C. Sefranek  tcs@cmcorp.com
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