On Tue, 6 Jan 2004 15:36:08 -0700, Robert Rolf wrote on Re:
[PIC:] Pic as an i2c slave. Debug bits:

>> I am also thinking of the possibility that the basic
>> compiler I use may mask interrupts when performing certain
>> "special" instructions (or rather macros) such as writing to
>> a LCD display module. This I could find by browsing in the
>> assembler file...
>
>It is quite likely that interrupts are being turned off in
>some routines.

I have browsed the whole assembler file compild fo my "big"
(8k) application, and found no trace of interrupt stuff
(enabling or disabling) by the compiler. This is what I
thought I would find, because that compiler has a special
system for interrupts, that are delayed under the current
basic instruction has been executed; in other words, basic
routines cannot be iterrupted in the immediate sens of the
term.

>Quickest way to find out is to set up a timer interrupt at
>the byte rate you expect from the I2C port and just toggle a bit.
>Any jitter in the width of the pulses will show you just how bad
>the latency is.

Nice and easy to do: I'll test it.

>You could also toggle a 'debug' bit as part of your I2C service
>routine. I found that setting a bit at the start, and clearing
>it just before I returned, gave me a great deal of insight into
>how well my various ISR routines were handling things, and helped
>me add additionally polling points as required.

I also use such methods.

Thank you for these suggestions,

Robert

* Xrobert.soubie@free.frX (veuillez supprimer les "X")
* http://www.astrosurf.com/soubie
* Au royaume des aveugles, les borgnes sont mal vus... - P.Dac

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