David Duffy (AVD) wrote:
> I'm trying to implement a simple 433MHz data link between two 16
> series PICs. I need to send 4 bytes (before encoding) across this
> link.

I've done that before a few times.

> I've used the KeeLoq example receiver code (TB045)

I have no idea what that is and don't feel like chasing it down.  You shoul=
d
be able to describe the relevant part in a paragraph or less.

> with a bit time of 800us and 8x sampling.

That's a rather slow bit rate.  By itself that's not necessarily bad, but i=
t
does cause more energy to be used per message than something more typical,
like 10KHz bit rate.  However, if you don't have a hardware data slicer, yo=
u
probably need to keep the bit rate low enough to be able to handle the
sample rate.

One implementation I did of a firmware bit slicer on a dsPIC used a 10KHz
bit rate, sampled at 10x, and used about 85% of the processor by doing that=
..
Obviously that's too much for a PIC 16.  I've done 10KHz bit rate
implementations on PIC 16 and 18, but those had a hardware data slicer.

> On the transmitter side it's a simple bit bang arrangement, using the
> data structure shown in TB045.

Again, I don't know what that is, and it's not clear whether it's relevant
anyway.

> The receiver sets the RxFull flag

What RxFull flag?  This is the first you mentioned it.

> that uses your typical 145027 type encoding.

Not mine.  I don't have a "typical 145027 encoding".

> I can't seem to figure out what's wrong and have been going around in
> circles somewhat.

Then explain what exactly your setup and problem are without relying on
vague references.  Define the parts we need to know.

> Has anyone been down this road before?

Obviously, as there are many instances of small devices that communicate
digitally over 434MHz.


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