Thread: programming help: part deux
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Unread 23-06-2002, 22:46
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#0047 (ChiefDelphi)
  
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Re: programming help: part deux
Posted by Rick Berube.

Engineer on team #121, Rhode Warriors, from Middletown H.S..

Posted on 1/23/2000 9:03 AM MST


In Reply to: programming help: part deux posted by Jon on 1/23/2000 1:44 AM MST:



: Does anyone know of a way to read only 1 input instead of all of them at once?
: i need to sample a sensor a lot and don't care for the rest...
: thanks,
: jon 190

Jon,
I don't think you can read just a bit. The data you want is only accessible to your PBasic program via the SERIN statement. The Master CPU is the one that has access to that data. It reads all the sensor data on the RC and then serializes the data to the Stamp IISX. An interesting experiment however, would be to see how fast the Master CPU can update the data. We know that the interface supports at least a 40 Hz update rate based on the specifications. Can it go faster? Perhaps, but you may also read stale data (that is, the Master CPU may update that data at a lesser periodic rate than you are polling at).

You can certainly minimize the time for the SERIN statement by not reading as many bytes. According to my calculations, theorectically it takes ~160 uS to receive each byte (@ 62500 baud). Keep in mind however, that this one SERIN statement also brings in all your playerstation data, so there will be practical liimitations to what you can remove from the data stream. Also, I believe once the initialization section of code runs, the format of the data stream is etched in stone until the next reset of the RC.

Perhaps a call to Innovation First is on order ot answer this question.

Regards,

Rick



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