> Hi Olin,
>
> Some weeks ago, I wrote to the Piclist because I needed help
> about asynchronous interrupt. You said to me that the 18's family
> has 2 levels of interrupt, but unfortunately, there is a bug with
> that feature which have been fixed very recently.
> I've phoned to many dealers, but none can make the difference
> between the bugged one and the fixed one. Eventualy, I haven't
> achieved to get a good PIC, even with huge efforts.
>
> So, let's go to the point. I really am sorry to ask you that, but is
> there a hope you can sell me one or two 18F452 without the bug.
> The company for which I work have an office in California.
> They are Fedex's customer, and I could ask Fedex to go and pick
> the PIC anywhere you want (home, office, ...).
> You will have nothing to do. We can pay you with a bank transfert
> or send you a cheque or anything you want.
>
> The problem is that I am a student and my thesis must be finished
> in one month. Otherwise, I would have waited for the non bugged
> PIC's to be available.

I only received 3 of the rev C0 18F252 parts myself, and I really can't
afford to part with any of them.  One is at a customer, another in a
duplicate circuit here to support the one at the customer, and the third
is being tested right now in a different project.  Also I got these for
free as samples, so it wouldn't be right for me to sell them to someone
else.

It helps to have a good relationship with the people in your local
Microchip office, but I understand that is difficult or impossible for a
student.  If you really can't get any rev C0 18F252 parts, then I think
your best options are:

1  -  Figure out how to use a single interrupt priority level.

2  -  Use one of the newer 18F parts that doesn't have the interrupt
priority bug.  However beware that some of these have other problems in
that they don't work at the full specified speed.  I consider the 18F1320,
for example, to be a 20MHz device until Microchip fixes this problem.

3  -  Use separate PICs to handle different interrupt conditions and have
them all somehow (IIC, SPI ?) talk to a central PIC that collects the
data.

Sorry I couldn't be more helpful.


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