Yeah im using the script exactly from your source and installed it exactly how you instructions say... My empeg still starts randomly accepting codes from the gps and will do stuff like turn randomizing on and off once i exit out of the gps screen... which reminds me, could you make it so that when you hit one of the buttons it goes back to the player.. it seems the only way to get back is to bring up hijack and then exit it.

-Greg

Sounds like the -s- isn't working on the player software you are running. I have had this in the past too. Are you on the current beta?

Pressing the knob exits empgps.

Cheers,

Rex.

Rex,

I am having a new problem and I am wondering if it is anything you have seen. If I enter EmpGPS before I have clean $GPRMC messages and I have other applications running (Telnetd and the Player, for example) the display will lock up and the buttons and knob are no longer read. If I run EmpGPS by itself then it will tolerate this condition without any lock ups.

If I wait until I have a GPS solution and the corresponding $GPRMC messages then all is well, until I go under an obstruction or lose coverage for some reason. I don't remember seeing this earlier. I have updated preinit and do now try to run Telnetd so it may be related to one of those. Telnet is really nice to have when the serial port is recommitted to the GPS.

I have also seen many of the things that have been mentioned above but will not repeat them here. I do think that there is some risk to the problem that seems to clobber the flash because of the large number of write cycles.

Any clues?

Lynn

It's the empeg ... I'll store a log file for you, but i won't be able to do it until sunday evening or monday. But I was planning on doing this anyway for testing purposes ;-)

Greg

Did anybody try this with the earthmate ?

I'm about 2 days from ordering it,
but if it won't work in my car I won't get it...

I *think* that the earthmate is a binary interface, not standard NMEA. That will limit your choices of software.

empgps doesn't support any binary interface.

BTW, empgps isn't dead, I've got lots of new code but nothing is going to happen with it until summer is over.

Cheers,

Rex.

Will it support the binary interface in the future ?
I could build a binary to NMEA translator,
but this could be done in software...

The tripmate is nearly impossible to get in germany/europe,
but the earthmate is easily available....

Doesn't gpsd translate some kind of binary format into NMEA?

I had no plans to add earthmate support but it would be easy to do. I do have an embedded unit here that has a binary output, I might use that in the car and therefore support that.

Someone with an earthmate could add support easily once I get source out there.

In the mean time, here's an interesting hacker style GPS receiver for $25:

http://www.bgmicro.com/lmad.htm

(I haven't got one -- yet -- and haven't tested it.)

Cheers,

Rex.

Cheers,

Rex.

Heh, at BGMicro, look at item # ACS1034.

A 40" shoe string...? Well, I guess you could buy a bunch and tie them end to end to find your way home but the ACS1394 GPS receiver might be better suited :-)

Looks like they might be sold out already though :-(

Cheers,

Rex.

Rex

Do you remember any more info about them? Perhaps they could be found else where?

I like playing with that sort of cheap reject/surplus type stuff trying to get it to work.

Damn they were Trimble GPS modules . $25 is (well would have been) a bargain. We used them in products here at work and they worked well.

PDF Manual is here

The entire documentation can still be found herehttp://www.bgmicro.com/pdf/acs1394.pdf.

These kind of units do crop up on the surplus market once in a while but sell out fast. I have one here that was just $20 but that does have a binary interface only. (Easy to use all the same.) Came with a nice patch antena too that was worth more than the $20 alone.

Cheers,

Rex.

Any chance of getting another release of the empgps software? That last one was close but the whole crashing thing ... you mentioned that you'd probably fixed that part already ...

g

I have a lot of new code and some fixes but to be honest, nothing is going to get done in the summer. Too much to do. I am even only using the car (and therefore empeg) when the weather is bad.

Hopefully I start to get some time in the fall.

Cheers,

Rex.

Any particular reason not to support gpsd and let it do the earthmate work for you, as opposed to yet another version of the "convert earthmate to something sane" code?

The orginal code on which this is based both predate gpsd and ran on an embedded non-linux system. That's all. I'm sure it could easily be added, I just haven't :-)

Cheers,

Rex.

I wasn't pointing at you particularly, but rather wondering for the benefit of potential suckers^H^H^H^H^H^Hcontributors.

They are back in stock at BGMicro. Probably not many so don't wait!

Cheers,

Rex.

Well, I went ahead and ordered one. Now I've just got to figure out how to build the serial interface circuit that I thought would be more of a buy-a-converter-cable-at-rat-shack style. We'll see how it goes. Anyone else actualy get one of these?

Matthew

It's not quite that simple :-) You just need a 5v power source (regulated) and a max232 or similar level converter. Ratshack probably has all the parts.

I have ordered one of these too. It will allow me to have only a small patch esposed in the car rather than the tripmate, which although painted is still an eyesore.

Cheers,

Rex.

Lookin forward to a next run of empgps ;-)

g

Thanks for the heads up Rex. I have ordered a couple. I just hope I don't get screwed by the shipping costs...

Their shipping charges are very reasonable. Might even be actual UPS cost. I wish more etailers were so straight forward!

For RS232 level shifting to 'safe' empeg levels, I'd use a Dallas Semi (now Maxim) DS275 RS232 transceiver.

Its a small 8 pin device, which steals its TX line 'idle' voltage from the RX line from the device at the end of the RS232 link [i.e. the empeg], thus removing the need for voltage invertors - which the MAX23X series provides.

This makes for a small and simple RS232 level convertor, without the need for capacitors that some MAX23X chips need.

all it needs is +5Volts - already needed for the GPS.

Of course if you want to provide the RTCM input as well on the second serial port on the GPS unit, then you'll need a second DS275, which may make a MAX233 a better option as it has 5 transceiver circuits, enough for TX and RX for both serial ports on the GPS unit.

You could probably power one of these DS275s from the serial port pins on the EMPEG [the DTR line is +12V] with a 7805 low power regulator and a cap.

Heck you'd probably be able to power the GPS unit from the same circuit if the 7805 was properly heatsinked and the GPs board didn't need more than 400ma.

I'm also sure you could set things up so that the GPS was powered and only powered down when the Empeg itself went to "sleep" [i.e. led stops blinking], thus allowing you to keep your GPS "engine" running [and ready to reacquire its position much more quickly] than from a cold start like when the power has just been turned on again, useful when you make a short stop and don't want to lose your GPS "lock".

The DS275 will probably work in this case but keep in mind that it is greatly limited compared with the MAX23x. There is another part -- forget the number right now -- like the MAX232 but with internal caps. Easier to use but more expensive. Personally I use MAX232s a lot, easy to hook up, cheap and reliable. Never had a problem with them.

The DS275 has issues with a full duplex signal but this is rarely needed with GPS. However, setting up this unit by downloading new firmware could be a problem though.

The GPS receiver has provision for a battery backup which will keep it's clock running and help speed locking on power up. Not as good as keeping the 'engine running' but should lead to sub-minute locking all the same.

Cheers,

Rex.

There is another part -- forget the number right now -- like the MAX232 but with internal caps.

Unless I'm mistaken, it's the MAX233.

You are right that the DS275 is not a perfect replacement for a MAX23X chip.

I use them for two reasons.

1. Smaller package size - a 8 pin device is less of a problem to work with than a 18 pin MAX232 (or 20 for a MAX233). Its more expensive (and harder to get though).

2. Few serial circuits need 'full spec' RS232 signals (+/- 12 volt signals), the DS275 can only provide a 'positive voltage' as high as the voltage you give it, for most applications this is 5 volts, so the signal won't travel too far, however for most applications a 5 volts serial signal is quite robust enough - many laptops do the same and only generate +/- 5 volts on the serial port.

The DS275 only provides TX and RX not CTS,RTS etc - these signals are generally optional and not used for most Serial interfaces these days.

However, I gather the GPS BG micro are selling does output pulses for its PPS - using this would require a full MAX23X chip.

. I have ordered a couple. I just hope I don't get screwed by the shipping costs...

FYI, BG Micro now shows the Trimbles as sold out. I'll see if I get the ones I ordered last eve. FWIW, they show "8 channel Motorola GPS boards coming this week" Encores? With antennas?? Can't know, but maybe an equivalent deal to the 6-channel Trimbles...

(edit: also, in the event that this wasn't mentioned earlier here, BG also has a doc with an example 232 interface here .