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Plato
01-18-2007, 08:28 AM
So I have been playing around with RF Transmitter & Receiver (#27980 & 27981) for the past few weeks, and hit a rather odd snag...

Transmitter Code:



junk VAR Word(4)
index VAR Nib

junk(0) = 2048
junk(1) = 2054
junk(2) = 2050
junk(3) = 2501

FOR index=0 TO 3
DEBUG ? junk(index)
NEXT

PULSOUT 7, 1200
SEROUT 7, 16468, ["!!", junk.HIGHBYTE(0), junk.LOWBYTE(0), junk.HIGHBYTE(1), junk.LOWBYTE(1),
junk.HIGHBYTE(2), junk.LOWBYTE(2)]


Receiver Code:


junk VAR Word(4)
Main:
SERIN 15, 16468, [WAIT("!!"), junk.HIGHBYTE(0), junk.LOWBYTE(0), junk.HIGHBYTE(1), junk.LOWBYTE(1),
junk.HIGHBYTE(2), junk.LOWBYTE(2)]
DEBUG ? junk(0)
DEBUG ? junk(1)
DEBUG ? junk(2)
GOTO Main


Now here is what has me scratching my head. When I run the code, the debug window on the transmitter shows that the array is filled with the correct values - no problem here.

However, in the debug window for the receiver code, I will get:


junk(0) = 2048
junk(1) = 2055
junk(2) = 0 <-------- THIS IS MY PROBLEM


The junk(2) value is not supposed to be 0. If I change the code to only SEROUT junk(0) and junk(1), then I will get:


junk(0) = 2048
junk(1) = 6 <------------ AGAIN, A PROBLEM


Anyone have any ideas as to why the last transmitted value is junk?

Thanks in advance!!

Mike Green
01-18-2007, 09:27 AM
I can think of two things, neither of which should be happening:
1) There is some delay in the transmitter or receiver that affects the reliability of the last few bits received.
2) The two Stamps have a timing difference so that after several characters, they lose synchronization

Some things to try:
1) Transmit an extra character. $FF has the advantage of leaving the transmitter off after the serial start pulse
2) Reduce the Baud from 9600 to 4800 and see what happens.
I know the transmitter/receiver is supposed to be good to 19.2KB, but the system isn't working.

Franklin
01-18-2007, 10:34 AM
You might also try a CR after the last debug in case you have something in the buffer.

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- Stephen