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For Sale: Etek EB-85A 5Hz GPS Modules. CHEAP!


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how about the cold powerup to lock ? is it me that is inpatient ?

The EB-85A will take awhile to acquire satellites (You've been spoiled by the SiRF III chip set used in the EM406/EM411). I noticed that it's similar to my handheld Garmin's on a cold boot. If you find that it takes ten minutes in your area then you might like to use the backup power feature. BTW, if you are trying to use it indoors, then initial satellites locks may be quite long.

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I've found cold boot time with the 85A to be very reasonable, generally < 1 minute, and very rarely > 2 minutes. For me it has been well below the patience threshold at which I'd consider a supercap backup (and I'm a very impatient bloke)

This cold-boot time is even in the presence of large amounts of 2.4Gig RF.

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about the slow lock, I have poor sky view in my indoor window location,

so that can explain it.

however it is exactly same spot I use to test EM406, and they are much faster.

The battery used for the EB85 is a 3.2V lithium, and the module remembers ALL

even last good position, after 8hr tested.

another person repported memory issue ?

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The battery used for the EB85 is a 3.2V lithium, and the module remembers ALL

even last good position, after 8hr tested.

My EB85 module(from sparkfun) remembers last good position but looses sentence output config after a day. Its probably less than a day but I haven't pin pointed the exact expiry time.

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I just fired a message off to Sparkfun to see if they can shed some light upon it.

Any updates to this? Has Sparkfun explained why some of their EB-85A's are default configured for 38.4K and some are 4800?

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I did send a message to SparkFun, but the response indicated that they didn't do anything special, and pointed me to their forum.

I am almost convinced that their modules are hard-coded using one of the 'limited number of program cycles' commands, since $PMTK314 has no effect on my unit.

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I am almost convinced that their modules are hard-coded using one of the 'limited number of program cycles' commands, since $PMTK314 has no effect on my unit.

It would have explained everything if Sparkfun was configuring them. Since they indicated that they don't do that, I'm now wondering if they asked the factory to set them to 38.4K baud/5-Hz for them. They made a big purchase, so they could have requested a special configuration. Beyond that, it sounds like Etek goofed up.

BTW, it's a shame that you can't get $PMTK314 to work. It is very helpful to turn off the unneeded fields. Check your syntax carefully -- it might just be an error in the string. I'm sure you've already done this many times, but look again. :)

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It would have explained everything if Sparkfun was configuring them. Since they indicated that they don't do that, I'm now wondering if they asked the factory to set them to 38.4K baud/5-Hz for them. They made a big purchase, so they could have requested a special configuration. Beyond that, it sounds like Etek goofed up.

BTW, it's a shame that you can't get $PMTK314 to work. It is very helpful to turn off the unneeded fields. Check your syntax carefully -- it might just be an error in the string. I'm sure you've already done this many times, but look again. :)

I guess the next step is to ask Etek if they custom configure them before shipment.

I can't find any 'query' forms of the additional configuration commands, so it doesn't seem like its possible to programmatically query the status of the module before sending a command which has a limited number of attempts.

It would be good to turn of the unneeded fields, but fortunately in my application it doesn't matter too much, the gps has a dedicated PIC which decodes the NMEA and relays it onto an i2c bus, so between packets it is idle and can easily ignore the extra ones.

The syntax seems fine, I have a bus analyzer on the RS232 line, and have checked and double-checked, it is really ignoring the request.

This mystery is a bit of a concern though, as I'm sure it is for you, I can just imagine receiving a new batch of these things programmed differently, and have to go in and modify firmware to support them.

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I guess the next step is to ask Etek if they custom configure them before shipment.

If the order size is sufficient, the OEM's will do whatever you want. Including wrapping the shipment in $100 bills. So, Sparkfun could have indeed requested 38.4K/5-Hz as defaults. Or, eTek could have accidentally sent Sparkfun some inventory destined for another user that wanted that.

It would be good to turn of the unneeded fields, but fortunately in my application it doesn't matter too much, the gps has a dedicated PIC which decodes the NMEA and relays it onto an i2c bus, so between packets it is idle and can easily ignore the extra ones.

I believe that turning off unneeded fields is for the best. There seems to be some anecdotal hints that some GPS modules will get less bogged down with calculations when you do that, so data becomes more real-time. It's just a armchair theory of mine and not at all based on mfg published info. Frankly, we wouldn't be having these discussions if they published decent documentation.

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I believe that turning off unneeded fields is for the best.

This is true. I measured that with all the fields ON (as by default) the average frequency of the position updates decreases to about 2Hz from about 3Hz with GGA and RMC fields only. In any case it's less than 5 Hz on average, even though there are intermediate bursts of 5Hz updates in the serial stream.

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Latest about lock times,

last night my EB85 and EM406 was in fine lock, then poweroff,

then this morning 8hr later, I measured in the front window of my car the startup time of them both, directly after eash other, and exactly same spot.

EM406 = 55 sec to 3 sats, 70 sec to 6 sats

EB85 = 47 sec to 6 sats, 50 sec to 8 sats

I have turned on the 4 sentences needed for tomtom navigator,

and drove to work today using EB85, in 1Hz mode,

WOW the position on the road is now MUCH more instantly,

and my speed follows much more, I have 150bhp so I can accelerate quite nice,

funny to see the tomtom screen say the same as the car speedometer :-)

Edited by ThomasScherrer
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thanks a lot.

is the EB-230 exactly software compatible with the EB85 ?

might be same chip in there ?

why did they "forget" to put in all working commands in the EB85 PDF files ?

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  • 2 weeks later...

Hello,

I just got my EB-85A and I was wondering what MAX chip you use to connect it to a RS232 port. MAX3232?

And anybody tried connecting the 2.8V output to a PIC? Did it work? Thanks :-)

Tom

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And anybody tried connecting the 2.8V output to a PIC? Did it work? Thanks :-)

If your PIC is powered by ~3V then it will work well. A 5V powered PIC, that uses the RS-232 hardware module, will not be reliable if you directly interface with the low voltage TTL that the typical GPS module provides. Yes, it has worked for some folks without translation, but it will be a YMMV sort of deal.

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  • 5 weeks later...
Hello,

I just got my EB-85A and I was wondering what MAX chip you use to connect it to a RS232 port. MAX3232?

And anybody tried connecting the 2.8V output to a PIC? Did it work? Thanks :-)

Tom

I was able to connect my EB-85 to my PIC!

Howto:

The standard UART port on my PIC (16F877) are ST (smidt-trigger), which only see a logical high at like 4V. Some other ports (like RB) are TLL, which see a logical high at around 2V. So the solution is to use software UART on a TTL pin.

This works perfectly.

The TX side can easily be done with 2 diodes or a voltage divider (2 resistors)

Tom

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After a while I figured out that software UART was not really an option. So I tried to come up with another solution

(could be trivial for electronics experts, but i'm just a newbee ;-) )

I used a 7407. This chip is a TLL chip that implements the function IN = OUT. Logical high on the in can be as low as 2V. The out is an open-collector port. This means it needs a pull up resistor, but you can take it to any voltage level you want.

So the GPS output (2.8V logical high) goes to the 7407 input and the corresponding output has a pull-up resistor to 5V.

The PIC UART output (5V logical high) goes to the 7407, and the corresponding output goes to a 2.8 voltage reference that was created using a voltage divider (2 resistors) connected between the ground and 5V.

I hope some people found my quest usefull :-)

Edited by tom
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  • 2 weeks later...

Tested mine today, it´s the 4800 baud firmware. With 4800 baudrate I have 6-7 satellites in 5 seconds after start. And with 38.6K baud I´ve got 10-11 satellites in 5 seconds too, great gps module :D thanks mr.-rc.cam

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  • 2 weeks later...
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