Topics

GPS i/p to elf 2k


jamesa4404 <jamesa4404@...>
 

I am thinking about using the elf 2k to read data from a GPS unit. Has anybody tried this? The idea is to get MPH data from the GPS and display it on a large LED display. Any suggestion on how to get the I/p and O/p it? Could basic be used for the program or would I have to go to ASM?


John Wren
 

Most GPSs output data at 4800 baud. I'll defer to the experts on what the
max speed is using bit-banged I/O, but if I was building something, I'd use
a CDP1854 UART.

I'd also do it assembly, although BASIC should be perfectly usable. The
nice thing a NMEA parser is a very simple state machine. Start the state
machine looking for a carriage return and/or linefeed, followed by a $. If
the next character is not the eginning of the NMEA word you're looking for,
reset the state machine. If it is, wait for the next character. Repeat
until you get your $GGA or whatever it you're looking for. Then start
counting commas, parse out the speed field, reset the state machine, you're
done.

You can probably get it down to about 20 instructions on average executed
between each character.

--jc

If at first you don't succeed, call in an airstrike.


On Fri, Jul 2, 2010 at 10:22 PM, jamesa4404 <jamesa4404@...> wrote:



I am thinking about using the elf 2k to read data from a GPS unit. Has
anybody tried this? The idea is to get MPH data from the GPS and display it
on a large LED display. Any suggestion on how to get the I/p and O/p it?
Could basic be used for the program or would I have to go to ASM?



[Non-text portions of this message have been removed]


James Tadlock <jamesa4404@...>
 

Thank you for the info. Do you think the GPIO card from the Sparetime Guys would give the needed i/o ports? Can you suggest a source fore info on the NMEA parser?

--- On Fri, 7/2/10, J.C. Wren <jcwren@...> wrote:


From: J.C. Wren <jcwren@...>
Subject: Re: [cosmacelf] GPS i/p to elf 2k
To: cosmacelf@...
Date: Friday, July 2, 2010, 9:31 PM


Most GPSs output data at 4800 baud.  I'll defer to the experts on what the
max speed is using bit-banged I/O, but if I was building something, I'd use
a CDP1854 UART.

I'd also do it assembly, although BASIC should be perfectly usable.  The
nice thing a NMEA parser is a very simple state machine.  Start the state
machine looking for a carriage return and/or linefeed, followed by a $.  If
the next character is not the eginning of the NMEA word you're looking for,
reset the state machine.  If it is, wait for the next character.  Repeat
until you get your $GGA or whatever it you're looking for.  Then start
counting commas, parse out the speed field, reset the state machine, you're
done.

You can probably get it down to about 20 instructions on average executed
between each character.

--jc

If at first you don't succeed, call in an airstrike.


On Fri, Jul 2, 2010 at 10:22 PM, jamesa4404 <jamesa4404@...> wrote:



I am thinking about using the elf 2k to read data from a GPS unit. Has
anybody tried this? The idea is to get MPH data from the GPS and display it
on a large LED display. Any suggestion on how to get the I/p and O/p it?
Could basic be used for the program or would I have to go to ASM?

 

[Non-text portions of this message have been removed]



------------------------------------

========================================================
Visit the COSMAC ELF website at http://www.cosmacelf.comYahoo! Groups Links








[Non-text portions of this message have been removed]


John Wren
 

There's good information at http://www.gpsinformation.org/dale/nmea.htm as
far as NMEA sentence structure goes. You'll have to check the output of the
GPS to see if yours supports the $GPVTG sentence, which would be ideal. If
not, the $GPRMC sentence is fine. The state machine is a 'write your own'
thing. Incidentally, there is a C compiler for the 1802. I haven't looked
at it lately, but I know Ted has done a lot of work on it, and it's pretty
robust now. No offense to Ted, but if you go that route, besides debugging
your own code, you may be helping find... ummmm... "not yet documented
unexpected behaviors".

The GPIO board isn't really appropriate. The base board has an RS-232 port.
It should work at 4800 baud, but it won't allow you to use the monitor, etc
while the GPS is connected. The Disk/UART/RTC board is really what you're
looking for. This board is really nice, because you can install Mike
Riley's ElfOS, which gives a disk system, assembler, editor, etc, and you
can do all your development right on the board.

How are you planning on interfacing to your display?

--jc

If at first you don't succeed, call in an airstrike.


On Sat, Jul 3, 2010 at 10:29 AM, James Tadlock <jamesa4404@...> wrote:



Thank you for the info. Do you think the GPIO card from the Sparetime Guys
would give the needed i/o ports? Can you suggest a source fore info on the
NMEA parser?

--- On Fri, 7/2/10, J.C. Wren <jcwren@... <jcwren%40gmail.com>>
wrote:

From: J.C. Wren <jcwren@... <jcwren%40gmail.com>>
Subject: Re: [cosmacelf] GPS i/p to elf 2k
To: cosmacelf@... <cosmacelf%40yahoogroups.com>
Date: Friday, July 2, 2010, 9:31 PM


Most GPSs output data at 4800 baud. I'll defer to the experts on what the
max speed is using bit-banged I/O, but if I was building something, I'd use
a CDP1854 UART.

I'd also do it assembly, although BASIC should be perfectly usable. The
nice thing a NMEA parser is a very simple state machine. Start the state
machine looking for a carriage return and/or linefeed, followed by a $. If
the next character is not the eginning of the NMEA word you're looking for,
reset the state machine. If it is, wait for the next character. Repeat
until you get your $GGA or whatever it you're looking for. Then start
counting commas, parse out the speed field, reset the state machine, you're
done.

You can probably get it down to about 20 instructions on average executed
between each character.

--jc

If at first you don't succeed, call in an airstrike.

On Fri, Jul 2, 2010 at 10:22 PM, jamesa4404 <jamesa4404@...<jamesa4404%40yahoo.com>>
wrote:



I am thinking about using the elf 2k to read data from a GPS unit. Has
anybody tried this? The idea is to get MPH data from the GPS and display
it
on a large LED display. Any suggestion on how to get the I/p and O/p it?
Could basic be used for the program or would I have to go to ASM?


[Non-text portions of this message have been removed]

------------------------------------

========================================================
Visit the COSMAC ELF website at http://www.cosmacelf.comYahoo! Groups
Links





[Non-text portions of this message have been removed]


James Tadlock <jamesa4404@...>
 

Again, Great Info. After sending the previous message I looked up info and found out what you said.The Disk/UART/RTC board is really what I need. That's OK because I wanted ono of those anyway. Ha Ha, wish, wish. Maybe some others have figured out a way to output info to large LED displays. Any one? I will keep the group posted on my sucess, Thanks to all.

--- On Sat, 7/3/10, J.C. Wren <jcwren@...> wrote:


From: J.C. Wren <jcwren@...>
Subject: Re: [cosmacelf] GPS i/p to elf 2k
To: cosmacelf@...
Date: Saturday, July 3, 2010, 8:57 AM


There's good information at http://www.gpsinformation.org/dale/nmea.htm as
far as NMEA sentence structure goes.  You'll have to check the output of the
GPS to see if yours supports the $GPVTG sentence, which would be ideal.  If
not, the $GPRMC sentence is fine.  The state machine is a 'write your own'
thing.  Incidentally, there is a C compiler for the 1802.  I haven't looked
at it lately, but I know Ted has done a lot of work on it, and it's pretty
robust now.  No offense to Ted, but if you go that route, besides debugging
your own code, you may be helping find... ummmm... "not yet documented
unexpected behaviors".

The GPIO board isn't really appropriate.  The base board has an RS-232 port.
It should work at 4800 baud, but it won't allow you to use the monitor, etc
while the GPS is connected.  The Disk/UART/RTC board is really what you're
looking for.  This board is really nice, because you can install Mike
Riley's ElfOS, which gives a disk system, assembler, editor, etc, and you
can do all your development right on the board.

How are you planning on interfacing to your display?

--jc

If at first you don't succeed, call in an airstrike.


On Sat, Jul 3, 2010 at 10:29 AM, James Tadlock <jamesa4404@...> wrote:



Thank you for the info. Do you think the GPIO card from the Sparetime Guys
would give the needed i/o ports? Can you suggest a source fore info on the
NMEA parser?

--- On Fri, 7/2/10, J.C. Wren <jcwren@... <jcwren%40gmail.com>>
wrote:

From: J.C. Wren <jcwren@... <jcwren%40gmail.com>>
Subject: Re: [cosmacelf] GPS i/p to elf 2k
To: cosmacelf@... <cosmacelf%40yahoogroups.com>
Date: Friday, July 2, 2010, 9:31 PM


Most GPSs output data at 4800 baud.  I'll defer to the experts on what the
max speed is using bit-banged I/O, but if I was building something, I'd use
a CDP1854 UART.

I'd also do it assembly, although BASIC should be perfectly usable.  The
nice thing a NMEA parser is a very simple state machine.  Start the state
machine looking for a carriage return and/or linefeed, followed by a $.  If
the next character is not the eginning of the NMEA word you're looking for,
reset the state machine.  If it is, wait for the next character.  Repeat
until you get your $GGA or whatever it you're looking for.  Then start
counting commas, parse out the speed field, reset the state machine, you're
done.

You can probably get it down to about 20 instructions on average executed
between each character.

--jc

If at first you don't succeed, call in an airstrike.

On Fri, Jul 2, 2010 at 10:22 PM, jamesa4404 <jamesa4404@...<jamesa4404%40yahoo.com>>
wrote:



I am thinking about using the elf 2k to read data from a GPS unit. Has
anybody tried this? The idea is to get MPH data from the GPS and display
it
on a large LED display. Any suggestion on how to get the I/p and O/p it?
Could basic be used for the program or would I have to go to ASM?


[Non-text portions of this message have been removed]

------------------------------------

========================================================
Visit the COSMAC ELF website at http://www.cosmacelf.comYahoo! Groups
Links



 

[Non-text portions of this message have been removed]



------------------------------------

========================================================
Visit the COSMAC ELF website at http://www.cosmacelf.comYahoo! Groups Links








[Non-text portions of this message have been removed]