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Subject: 
Re: legOS (-> Interdisciplinary Learning?)
Newsgroups: 
lugnet.robotics
Date: 
Tue, 1 Dec 1998 21:40:32 GMT
Original-From: 
Tim McSweeney <TIM@AMS.CO.stopspamNZ>
Viewed: 
2622 times
  
A simpler way to look at this is to say a message consists of 8 bits (hece
0-255)

Bit 1 = team 0=prey 1=predator   (High Bit)
Bit 2 = state, 0=mobile 1=active
Bit 3 = light
Bit 4 = Touch
Bit 5 = Compound RCX
Bit 6 = Inquire/Respond
Bits 7 and 8 = bot number (0 to 3)  (Low Bit)

I can't remember if the RCX has bitwise operations and I'm at work so I
can't go looking it up but the easy way to test it is to do a logical and of
the message with a bit mask and check for equality with 0

For example if we want to test of the message we recieved has a light sensor
w do

if (msg AND 00100000) equals 0  then it's has a light sensor else it doesn't

The bot number is extracted by

(msg and 00000011) which should give you an 8 bit integer number in the
range 0 to 3





Note: this is a bit kack handed, it's more traditional to use a one bit to
represent the presence of something rather than absence but that's up to
you.


Cheers
Tim
-----------------------------------------------------------------------
int main(int _,int __){int i[3]={0xFE101010,0xFE1010FE,0xFE929282};if(_
==1)for(_=0,__=0;(__<4);_=(_+1>=24)?++__+0*putchar('\n'):_+1){putchar(
main(_+2,__)?(main(_+2,__+1)?' ':'_'):' ');main(_+2,__)&&!main(_+3,__)?
putchar('/')+0x0*_++:0;}else return((_>=26)||(__>=4))?0:i[(_-2)/8]>>(3-
__)*8>>(_-2)%8&0x1;}
-----------------------------------------------------------------------






X = the IR send number.

X <= 128 indicates that the RCX is on 'team one' (or,
alternately, 'prey').
X > 128 indicates 'team two', or 'predator'. X = X - 128.

X <= 64 indicates that the RCX is mobile/in motion.
X > 64 indicates that the RCX is stationary. X = X - 64.

X <= 32 indicates that the RCX has (one or more) light sensors.
X > 32 indicates that the RCX has no light sensor. X = X - 32.

X <= 16 indicates that the RCX has (one or more) touch sensors.
X > 16 indicates that the RCX has no touch sensors. X = X - 16.

X = 8 indicates that the RCX is attached to a bot with more
than one RCX.
X > 8 indicates that the RCX is solo. X = X - 8.

X <= 4 indicates that the RCX is inquiring/pinging.
X > 4 indicates that the RCX is answering/responding. X = X - 4.

This leaves us with X equal to 1 through 4. We use this last number to
distinguish bots on a team (obviously, in this example, there
could be a max
of 4 bots on a team).

So, to sum up this overblown and excessive data transfer:

A bot sends the code 236. X = 236.
236 > 128. The bot is on team 2 (a predator). 236 - 128 = 108.
108 > 64. The bot is stationary (perhaps a venus fly-trap).
108 - 64 = 44.
44 > 32. The bot has no light sensor. 44 - 32 = 12.
12 <= 16. The bot has one or more touch sensors. 12 - 0 = 12.
12 > 8. The bot only has one RCX. 12 - 8 = 4.
4 <= 4. The bot is sending the message as a 'ping', or
question. 4 - 0 = 4.

X now equals 4. This means the bot is bot #4 on the predator team.

So, you've got a stationary predator without light sensors,
but with touch
sensors, running on a single RCX, that is requesting
information from the
world in general (perhaps another predator, upon hearing
this, will respond
with an 'answer' to inform Predator #4 that it is in the
vicinity -- or,
upon hearing this request, a prey bot might use a flashing
light (being
aware that Predator #4 has no light sensors) to notify its
teammates of its
location.) A little far-fetched, but with enough forethought,
a lot can be
achieved using communication this basic.

Simplistic, yes, but it shows that you can jam a lot of data into one
number. And sending a sequence of IR transmissions is also a
fairly easy
process, to allow you a much more complex string of data.

Of course, we've already contemplated bots that purposefully
lie... which,
in my mind, is getting quite a bit too close to human for
comfort. Could the
polygraph sensor be far behind?

-- Tom Pierce








Stefano







+-----------------------------------------------------------+
| Stefano Franchi                                           |
|                                                           |
| Department of Philosophy    Phone: Off:  (650) 723-2192   |
| Stanford University                Home: (650) 497-2812   |
| Stanford, CA 94305          Fax:         (415) 723-0985   |
| USA                                                       |
|                                                           |
| e-mail: franchi@csli.stanford.edu                         |
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