2P serin to scratchpad (was Garmin GPS III+ interface)
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> The biggest problem you will likely encounter is that reading a
> single and entire NMEA sentence on the BS2SX is very hard. The
> BS2P has the ability to input directly to the scratch pad ram using
> serin, as done in the sample code from the Parallax site. That
> command is not available on the 2SX.
Hey Chris,
Can you point me to a link that shows that example of using serin
directly to scratchpad memory? I searched their site but couldn't
find it.
The project I'm working on is talking to the diagnostic connector on
a GM car. The ALDL line is 8192/8/1/N TTL and the data stream I want
to capture is almost 70 bytes long, also there is no flow control at
all. I've got a BS2 and it just can't keep up using serin to read a
few bytes at a time. By the time I get to the next serin command,
I've lost several bytes.
The initial project was to simply control two electric cooling fans
and A/C cut-off based on the ALDL data for speed, water temp, RPM,
throttle position. Once I had that working I want to add an LCD
display to show real-time readings and trouble-code display/clearing.
I looks like I have 3 options now.
The first option is to use something like a MAX3100 with my BS2 and
hope the 8 byte FIFO is enough. I think this could be a problem
since the shiftin can only transfer 16kbps. I'm not sure if I could
read and process a few bytes before the buffer overflowed.
The second option is to use the Javelin stamp which looks like it
will easily do everything I want plus more.
The third option is the one Chris just pointed out. Use the 2P and
let serin write the datasream directly into scratchpad where I can
parse it a lot more easily, plus the added speed and memory size
means I can add all the features I would probably ever need.
The price difference between the BS2P and the Javelin is only $10 and
cost isn't a major issue.
At the moment I'm leaning towards option 2 because it seems to be a
pretty powerful chip. I know this isn't the Javelin forum but can
anyone give me some advantages/disadvantages of the 2P vs Javelin.
Is there a simpler solution I have overlooked or any other
suggestions?
Thanks,
Joe
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> single and entire NMEA sentence on the BS2SX is very hard. The
> BS2P has the ability to input directly to the scratch pad ram using
> serin, as done in the sample code from the Parallax site. That
> command is not available on the 2SX.
Hey Chris,
Can you point me to a link that shows that example of using serin
directly to scratchpad memory? I searched their site but couldn't
find it.
The project I'm working on is talking to the diagnostic connector on
a GM car. The ALDL line is 8192/8/1/N TTL and the data stream I want
to capture is almost 70 bytes long, also there is no flow control at
all. I've got a BS2 and it just can't keep up using serin to read a
few bytes at a time. By the time I get to the next serin command,
I've lost several bytes.
The initial project was to simply control two electric cooling fans
and A/C cut-off based on the ALDL data for speed, water temp, RPM,
throttle position. Once I had that working I want to add an LCD
display to show real-time readings and trouble-code display/clearing.
I looks like I have 3 options now.
The first option is to use something like a MAX3100 with my BS2 and
hope the 8 byte FIFO is enough. I think this could be a problem
since the shiftin can only transfer 16kbps. I'm not sure if I could
read and process a few bytes before the buffer overflowed.
The second option is to use the Javelin stamp which looks like it
will easily do everything I want plus more.
The third option is the one Chris just pointed out. Use the 2P and
let serin write the datasream directly into scratchpad where I can
parse it a lot more easily, plus the added speed and memory size
means I can add all the features I would probably ever need.
The price difference between the BS2P and the Javelin is only $10 and
cost isn't a major issue.
At the moment I'm leaning towards option 2 because it seems to be a
pretty powerful chip. I know this isn't the Javelin forum but can
anyone give me some advantages/disadvantages of the 2P vs Javelin.
Is there a simpler solution I have overlooked or any other
suggestions?
Thanks,
Joe
__________________________________________________
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Comments
http://www.parallaxinc.com/html_files/resources/resources.htm
It is the datalogging and GPS project.
If you look at the serin command you will find something like STRSP, which
is the almost totally undocumented feature that lets you write from serin
directly to scratchpad ram. I am not certain how many bytes you can do, but
I think it is only about 60. Somewhere in the documentation it tells you
what the highest number is used for and you have one less to work with.
If there is a common preable or sequence for the data stream I solved my
problem by doing two waitfor "XXX" serin commands. The first serin read the
beginning of the string, stored it etc. the second serin skipped over the
part that I read in the first serin and read the last part of the string.
This works if the data string has some structure and you know with some
certainty that the same information will occur in about the same place in
each string.
I don't know anything about Javelin.
Original Message
From: Joe Sass [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=0zOGuymi7MLGFFmS_ekMWtdiDACK-70pBwM7q5m-ztkAsYAxdqAJ8E6_I5lUJTYKozcMDcIy5D0]joesass@y...[/url
Sent: Monday, August 26, 2002 11:25 AM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Re: 2P serin to scratchpad (was Garmin GPS III+
interface)
> The biggest problem you will likely encounter is that reading a
> single and entire NMEA sentence on the BS2SX is very hard. The
> BS2P has the ability to input directly to the scratch pad ram using
> serin, as done in the sample code from the Parallax site. That
> command is not available on the 2SX.
Hey Chris,
Can you point me to a link that shows that example of using serin
directly to scratchpad memory? I searched their site but couldn't
find it.
The project I'm working on is talking to the diagnostic connector on
a GM car. The ALDL line is 8192/8/1/N TTL and the data stream I want
to capture is almost 70 bytes long, also there is no flow control at
all. I've got a BS2 and it just can't keep up using serin to read a
few bytes at a time. By the time I get to the next serin command,
I've lost several bytes.
The initial project was to simply control two electric cooling fans
and A/C cut-off based on the ALDL data for speed, water temp, RPM,
throttle position. Once I had that working I want to add an LCD
display to show real-time readings and trouble-code display/clearing.
I looks like I have 3 options now.
The first option is to use something like a MAX3100 with my BS2 and
hope the 8 byte FIFO is enough. I think this could be a problem
since the shiftin can only transfer 16kbps. I'm not sure if I could
read and process a few bytes before the buffer overflowed.
The second option is to use the Javelin stamp which looks like it
will easily do everything I want plus more.
The third option is the one Chris just pointed out. Use the 2P and
let serin write the datasream directly into scratchpad where I can
parse it a lot more easily, plus the added speed and memory size
means I can add all the features I would probably ever need.
The price difference between the BS2P and the Javelin is only $10 and
cost isn't a major issue.
At the moment I'm leaning towards option 2 because it seems to be a
pretty powerful chip. I know this isn't the Javelin forum but can
anyone give me some advantages/disadvantages of the 2P vs Javelin.
Is there a simpler solution I have overlooked or any other
suggestions?
Thanks,
Joe
__________________________________________________
Do You Yahoo!?
Yahoo! Finance - Get real-time stock quotes
http://finance.yahoo.com
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