Subject:
|
Re: Lego Network Protocol questions
|
Newsgroups:
|
lugnet.robotics
|
Date:
|
Thu, 6 May 1999 16:46:35 GMT
|
Viewed:
|
916 times
|
| |
|
|
Ben Laurie <ben@algroup.co.uk> wrote:
> I'd've thought that collision detection would not be hugely reliable,
> anyway - I'd guess that your own signal would drown out anything else.
> This is a completely untested assumption, though!
This is a possibility I hadn't considered, and it sounds reasonable to
expect to see that effect at some point. I never tested how a second
source affects echo reception, but it seems easy enough to test. If I get
around to testing this I'll share the results.
> > I think something like this is possible on the H8. You might be able to
> > use the rhythm established by the reception of bytes from other RCXs to
> > keep clocks in sync, although the timings would be somewhat coarse grained
> > and you'd have to leave space for whatever the margin of error ended up
> > being.
>
> I'm not sure why you think the timing would be coarse? It only has to be
> fine enough to get you down to the bit level (meaning you waste around
> 10% of the available bandwidth in avoiding overlap), and most UARTs
> sample 16 times per bit, so that should be easy...
Even though the UARTs may sample 16 times per bit, and even though the UART
knows when each bit has arrived, the RCX does not let you get at this
information. So as far as I know you are stuck reading a timer only after
having received each individual byte, not bit. Also, since you have to do
the measurement in an ISR, the timings are not entirely reliable.
-Kekoa
|
|
Message has 1 Reply:
 | | Re: Lego Network Protocol questions
|
| (...) Sure, but you should be able to get the edge of the stop bit(s) to within 1/16th bit+interrupt latency (which I'd guess is tiny in comparison to the bit timing) which gives you the position of any other bit just as accurately (give or take (...) (25 years ago, 6-May-99, to lugnet.robotics)
|
Message is in Reply To:
| | Re: Lego Network Protocol questions
|
| (...) I'd've thought that collision detection would not be hugely reliable, anyway - I'd guess that your own signal would drown out anything else. This is a completely untested assumption, though! (...) I'm not sure why you think the timing would be (...) (25 years ago, 6-May-99, to lugnet.robotics)
|
5 Messages in This Thread:
 
- Entire Thread on One Page:
- Nested:
All | Brief | Compact | Dots
Linear:
All | Brief | Compact
This Message and its Replies on One Page:
- Nested:
All | Brief | Compact | Dots
Linear:
All | Brief | Compact
|
|
|
|
