Subject:
|
Re: CM-RCX comm (Anyone using Scout->MicroScout/CodePilot ?)
|
Newsgroups:
|
lugnet.robotics
|
Date:
|
Wed, 31 Jan 2001 14:05:58 GMT
|
Original-From:
|
Marco C. <marco@IHATESPAMsoporcel.pt>
|
Viewed:
|
1038 times
|
| |
|
|
At 06:59 31-01-2001 -0600, Steve Baker wrote:
> "Marco C." wrote:
> > Every Wait(10) was correctly measured as a Timer(3)==1, and every Wait(50)
> > as a Timer(3)==5 and so on...
> Well, yes - but then crystal oscillators are quite accurate (but crucially,
> not 100% accurate). You might have to run as long as one or two MILLION
> attempts before you see an error - but you *will* see an error if you do
> it for long enough.
>
> If your code does one test per second (say) and the clocks differ by one
> part per million (which I believe to be a reasonable figure) - then it
> might take as long as 11 days for you to see a problem....or it might happen
> on the very first try.
Yes, I understand.
Lego created VLL for barcode reading (CodePilot, and then MicroScout).
Barcode reading is error prone, so are other forms of serial communication.
Through the use of the VLL Checksum bits and timeouts, one can invalidate
bad VLL sequences, so the danger of a StopAllMotors message being mistaken
by a StartAllMotorsAtFullSpeed is minimized and the mixed pBrick bot
doesn't commit "suicide" by mistake ;) (ok, it can happen anyway...)
The best way to use this lib, is by using a bidirectional communication.
The VLL message sender will wait for a ACK return message, repeating the
message if anything went wrong.
In some situations, I can use a unidirecctional approach.
For instance: RCX sends a VLL message to a CodePilot to open it's claw. The
tip of the finger of the claw has a RCX sensor. RCX knows if CodePilot got
the message by sensing that the claw opened.
Another example: Remote controlled roverbot using a CyberMaster for
navigational and RF comms and RCX for robotic arm control. All actions are
monitored by an operator through a Lego Cam or wireless Xcam. When the
operator commands CyberMaster to send a VLL message to the RCX to rotate an
arm and the operator sees nothing, all it has to do is repeat the command.
Question: Is there anyone here that uses the Scout->CodePilot/MicroScout
comms ? What is the hit/miss rate in this case ?
mc.
|
|
Message is in Reply To:
 | | Re: CM-RCX comm
|
| (...) That's exactly what my common sense made me believe. But various tests I did, using a dump of a Datalog with the timmings measured by the RCX, proved me wrong. Every Wait(10) was correctly measured as a Timer(3)==1, and every Wait(50) as a (...) (23 years ago, 31-Jan-01, to lugnet.robotics)
|
20 Messages in This Thread:
 
 
 
- Entire Thread on One Page:
- Nested:
All | Brief | Compact | Dots
Linear:
All | Brief | Compact
|
|
|
|
