Subject:
|
Re: Need Masses of Technical Info
|
Newsgroups:
|
lugnet.robotics
|
Date:
|
Tue, 12 Jun 2001 06:16:53 GMT
|
Viewed:
|
447 times
|
| |
|
|
Sean Watson <SeanWatson@ec.rr.com> wrote:
> communication FROM the RCX TO the IR Tower/PC (as opposed to the other way
> around)
RCX->PC is difficult because of the tower hardware. The tower shuts off a
few seconds after it completes transmission to save power. Messages from
the RCX that arrive during or after the shut off are truncated or not
received. The tower works best in request/reply mode where the PC requests
something and the RCX replies to it. In request/reply mode, a good
practical cap on the max number of data bytes to transfer from RCX to PC in
one go is 256 (does not include header, complements, or checksum). Larger
sizes might work, but I know 256 works. When grabbing the ROM image, I
distinctly remember having to reduce the size to avoid losing data to the
tower shutting off. I ended up using the 256 size.
> communication from RCX to RCX
This is not a problem, but if you use the standard firmware you are limited
to one byte transfers. If you roll your own code to do this you can do
pretty arbitrary stuff modulo general reliability of IR communication,
which can be flaky depending on your lighting environment, orientation of
RCXs, etc. I think LegOS might include some useful general IR code, but I
am not sure.
> and how the H8 chip talks to the RAM included in the RCX (not the RAM in the
> H8, but the 32K of external RAM, I was not able to figure this out from the
> Hitachi manual)
If I remember correctly one or more pins are hardwired to tell the H8 to
expect a memory to be attached to it. I/O ports 1, 2, and 3, and parts of
port 4 are therefore dedicated to accessing the external RAM. The RAM is
memory mapped into the H8 address space. There should be a diagram in the
H8 docs that shows the various memory maps. One of those is the right one.
Since I don't have the docs in front of me I can't tell you which it is,
but you should be able to figure it out.
-Kekoa
|
|
Message has 1 Reply:
 | | Re: Need Masses of Technical Info
|
| (...) After you get some data, like 768 bytes or something, send another signal from the PC. The RCX waits for this, and then sends another 768 bytes. This should keep the tower on for the right amount of time. Also, be careful of sending too much (...) (23 years ago, 12-Jun-01, to lugnet.robotics)
|
Message is in Reply To:
| | Need Masses of Technical Info
|
| I am a student at the University of North Carolina at Wilmington. I am doing undergraduate research on Neural Networking and Artificial Intelligence, and the Mindstorms have become my choice of implementation. Even though I have found a vast amount (...) (23 years ago, 12-Jun-01, to lugnet.robotics)
|
4 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
|
|
|
|
