AVR-Chat

On Tue, Jul 28, 2009 at 10:22:37AM -0400, David VanHorn wrote:
> > As you said, "poorly written", as it is not clear whether the 30 mS
> > timer starts with the first byte, or is a watchdog which flushes the
> > buffer after 30 mS of inactivity.
> 
> Right.. Sometimes with these products, all you can do is try it and
> see. I suspect it is an inactivity timer, but it could just as well be
> the other one.

Then again they say nothing about synchronization between radios. There
may be a window which they always alternate back and forth no matter
whether one has data or not so that each only has one opportunity to
transmit every 30 mS. This results in yet another color to the real time
performance of this radio system.

I successfully used an Aerocomm radio purchased via Mouser.com on a
project. Had a minor problem with my data frame being split between
radio packets. The Visual Basic program on the PC end couldn't handle a
pause in the middle of a data frame. The VB code made no sense to me so
I "fixed" the embedded end. The Aerocomm module had an output pin which
indicated start of RF frame, so I simply wrote my data packets
immediately after being signaled by the radio. In retrospect that is
what I should have been doing in the first place.

Did not have any "real time" requirement above, only requirement was to
get the data from the robot to a disk file. Commands to the robot were
on the reverse channel and only had to be timely as the robot was not
being steered remotely. Basically only speed, direction, start, and stop
were sent.

-- 
David Kelly N4HHE, dkelly@HiWAAY.net
========================================================================
Whom computers would destroy, they must first drive mad.