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 Robotics / RCX / NQC / 144
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Subject: 
Re: Tasks vs. program slots
Newsgroups: 
lugnet.robotics.rcx.nqc
Date: 
Sat, 18 Sep 1999 06:14:51 GMT
Viewed: 
2187 times
  
Hello Dave,

First, let me thank you for NQC ... you've made my RCX playing
tremendously more rewarding.

I've been wanting to use a Sharp IR receiver to demodulate the signal
from a LEGO remote control, and then a PIC to decode the rx output
for use by an external controller (not the RCX).  Would you please
give me a little more of an explanation of the remote's transmitted
signal ... comm protocol, timing, etc.  My lack of knowledge is
keeping me from making any sense out of what I see on the 'scope
coming out of the Sharp IR receiver.

Thanks,
- Nick -

Dave Baum wrote:
[snip]
The remote control always sends the same sort of packet:

d2 xx yy

where xxyy is a sixteen bit bit-field indicating what features should be
activated:

xxyy
0001 Message 1
0002 Message 2
0004 Message 3
0008 Motor A Forward
0010 Motor B Forward
0020 Motor C Forward
0040 Motor A Backward
0080 Motor B Backward
0100 Motor C Backward
0200 Run Program 1
0400 Run Program 2
0800 Run Program 3
1000 Run Program 4
2000 Run Program 5
4000 Stop Program
8000 Beep

These can be ORed together.  I don't know if all combinations are legal,
but you can certainly combine the motor options together.

The remote sends multiple copies of the packet while the button is held
down, then sends a d20000 when the button is released.

Unfortunately, I think these codes are ignored when encountered within a
program.  I tried the one to run program 5 from within an NQC program:

asm { 0xd2, 0x20, 0x00 };

It had no effect.

Dave Baum



Message has 1 Reply:
  Re: Tasks vs. program slots
 
(...) What exactly does the Sharp IR receiver do? If it uses Sharp's ASK modulation, then you may have a problem. Ideally, what you want is something like a phototransistor to a good preamp, followed by a bandpass around 38kHz, then some sort of (...) (25 years ago, 18-Sep-99, to lugnet.robotics.rcx.nqc)

Message is in Reply To:
  Re: Tasks vs. program slots
 
(...) The remote control always sends the same sort of packet: d2 xx yy where xxyy is a sixteen bit bit-field indicating what features should be activated: xxyy 0001 Message 1 0002 Message 2 0004 Message 3 0008 Motor A Forward 0010 Motor B Forward (...) (25 years ago, 18-Sep-99, to lugnet.robotics.rcx.nqc)

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