GPS Interfacing
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Posts: 46,084
Mike-
It's reasonably safe to assume your GPS is sending its serial data
LSB first. That's a pretty universal standard and it's what your
Stamp (and virtually every other async serial device) expects to see.
A high start bit and low stop bit mean it's transmitting in what your
Stamp understands as "non-inverted" mode. BS2SX/4800/non-inverted
translates to Baudmode 500 if I read the chart right.
Try:
SERIN 1,500,[noparse][[/noparse]name]
Steve
It's reasonably safe to assume your GPS is sending its serial data
LSB first. That's a pretty universal standard and it's what your
Stamp (and virtually every other async serial device) expects to see.
A high start bit and low stop bit mean it's transmitting in what your
Stamp understands as "non-inverted" mode. BS2SX/4800/non-inverted
translates to Baudmode 500 if I read the chart right.
Try:
SERIN 1,500,[noparse][[/noparse]name]
Steve
Comments
it with a Garmin Emap GPS device for a college design
project. I am having difficulty getting the stamp to
correctly interpret the incoming serial data from the
GPS.
I'm using the Simple text output, with 4800 baud.
I'm trying to use the Serin command, but so far the
Stamp isn't correctly interpreting the data. I have
put it on the oscilloscope, and it appears that the
GPS is sending out, for every ascii character: One
Start bit, which is high, eight data bits, LSB first,
and then a low stop bit. I have found that i can get
the correct ascii data by taking the data bits of
character, reversing their order, and then inverting
them. Here is the command I have used to accept the
data:
serin 1, 16468, [noparse][[/noparse]name]
I think i can take care of the inversion by
changing the 16468, I'm not too worried about that
part, but i don't have any idea how to get the bits in
the correct order. (MSB first) I've looked in the
manuals but I can't seem to find any serin modifiers
that toggle that. Furthermore, I don't think I can
use the shiftout function, because I don't have anyway
to clock the data out of the GPS. If anyone has any
ideas, I would be EXTREMELY grateful! Thank you!
Mike Irvine
P.S. I believe that the data coming out of the GPS is
MSB first. My memory could be wrong, and it could be
that the data out of the GPS is LSB and the chip is
reading MSB. Either way, it's backwards. Thanks
again!
value = value REV 8
Regards
ECO
Original Message
From: <mjirvine@m...>
To: <basicstamps@yahoogroups.com>
Sent: lundi 5 f