interfacing with GPS through serial port
Sounds the same as the eXplorist - there's a Windows driver needed to map the USB connection onto COM3 or other port. So the answer is no, it won't work with the PSP - that needs an RS232 serial connection on the GPS for it to work.
Please, don't ask if it can be made to work with the PSPs USB port ;-)
Jim
Please, don't ask if it can be made to work with the PSPs USB port ;-)
Jim
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ZeroAltitude
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Garmin eMap RS232 (NMEA) > PSP (Serial)
Hello,
I'm new to the PSP scene, but I'm pretty at home programming. Deniska, I found your work on the Map software really spectacular. Seeing your specs for how you interfaced your Holus, I tried the same thing with my Garmin eMap. I was wondering if you could give me a few pointers.
What I've done hardware-wise is pretty much a copy of what you did with your GPS: I've wired TX from the GPS to the RX pin of my PSP using the headphone cable which I hacked up and used. I've wired the GND pin from the GPS to the GND pin of my PSP. Between the TX and RX, I've inserted 4k of 1/4 watt resistance via 4 1k 1/4 watt resistors in serial. I've noted that the Garmin eMap claims to support NMEA output, and runs at 4800 baud. So, I got your pspgpslim software, and reset the default SIO baud rate to 4800. I recompiled against the toolchain and installed the results on my PSP.
Verifying a good connection with my multimeter, I put everything together. But nothing was happening in your software when I ran my tests. So, I modified your code to output data about failed NMEA sentences, just to verify that the PSP was indeed registering data on the serial port. And it was! So here are my questions:
* given that there is data on the serial port, am I still possibly in trouble if my resistance on the line is wrong? That is, can having too much resistance give *bad* instead of non-existant data to my PSP? Should I try less resistance? [EDIT: I appear to be getting that 'lots of funny characters on the screen' problem you described in an earlier post; did you fix that by reducing the line resistance?]
* I've so far tried my PSP only indoors with this, when my GPS has not acquired a satellite -- is this my problem? Does my GPS send data that your software does not recognize when it doesn't have valid telemetry?
* Any other hints you might have regarding why the output detected in pspgpslim doesn't seem to correspond to valid NMEA sentences when hooked up in the way I described to my Garmin eMap?
That I got this far with what you posted on your site is a real tribute to the good data you described so well. Thank you in advance for your help.
ZeroAltitude
I'm new to the PSP scene, but I'm pretty at home programming. Deniska, I found your work on the Map software really spectacular. Seeing your specs for how you interfaced your Holus, I tried the same thing with my Garmin eMap. I was wondering if you could give me a few pointers.
What I've done hardware-wise is pretty much a copy of what you did with your GPS: I've wired TX from the GPS to the RX pin of my PSP using the headphone cable which I hacked up and used. I've wired the GND pin from the GPS to the GND pin of my PSP. Between the TX and RX, I've inserted 4k of 1/4 watt resistance via 4 1k 1/4 watt resistors in serial. I've noted that the Garmin eMap claims to support NMEA output, and runs at 4800 baud. So, I got your pspgpslim software, and reset the default SIO baud rate to 4800. I recompiled against the toolchain and installed the results on my PSP.
Verifying a good connection with my multimeter, I put everything together. But nothing was happening in your software when I ran my tests. So, I modified your code to output data about failed NMEA sentences, just to verify that the PSP was indeed registering data on the serial port. And it was! So here are my questions:
* given that there is data on the serial port, am I still possibly in trouble if my resistance on the line is wrong? That is, can having too much resistance give *bad* instead of non-existant data to my PSP? Should I try less resistance? [EDIT: I appear to be getting that 'lots of funny characters on the screen' problem you described in an earlier post; did you fix that by reducing the line resistance?]
* I've so far tried my PSP only indoors with this, when my GPS has not acquired a satellite -- is this my problem? Does my GPS send data that your software does not recognize when it doesn't have valid telemetry?
* Any other hints you might have regarding why the output detected in pspgpslim doesn't seem to correspond to valid NMEA sentences when hooked up in the way I described to my Garmin eMap?
That I got this far with what you posted on your site is a real tribute to the good data you described so well. Thank you in advance for your help.
ZeroAltitude
I would try a smaller resistance, perhaps 500 or 200 Oms or event connect it directly (w/o a resistor)
It appears that your device power is only 3.15V (if II read the spec correclty) so my guess is that TX out put is even lower...
I did get funny characters with higher resistor values at some point...
Not having a lock on Satelites should not mater - your device should output some NMEA even if there is no signal...
I think someone already made connection to a similar garmin device..
Look thru my forums for more info:
http://deniska.dcemu.co.uk/
It appears that your device power is only 3.15V (if II read the spec correclty) so my guess is that TX out put is even lower...
I did get funny characters with higher resistor values at some point...
Not having a lock on Satelites should not mater - your device should output some NMEA even if there is no signal...
I think someone already made connection to a similar garmin device..
Look thru my forums for more info:
http://deniska.dcemu.co.uk/