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Mr.RC-Cam

For Sale: SiRF III GPS Modules. CHEAP!

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Aug-13-2007 UPDATE: The special offer is retired. It was a pleasure helping out while I could with this superb GPS module deal.

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Start of original discussion:

I have several brand new (factory fresh) GLOBALSAT EM-411 SiRF III WAAS enabled GPS receiver modules. While they last: $44.50 USD each plus shipping.

These are fully integrated 5VDC powered GPS modules. They include a built-in patch antenna and a very sensitive 20-channel receiver. Default GPS data is standard NMEA text format sent as a 1-Hz updated 4800 baud, 3.3V TTL non-inverting RS-232. And it is tiny; only 1.2" square x 0.4" High.

This GPS is exactly the same as the popular EM-406, except the 6-pin connector has a different pin order. It can be used in the place of a EM-406, with no change in performance, if you just swap pins 3 and 4 on the included interconnect cable.

If interested, PM me from the forum. Please do not use email or the spam filter may lose your message.

Data sheet (now includes correct pinout details): http://www.dpcav.com/data_sheets/EM411Prod...ct_Guide1_2.pdf

Photo of EM-411. USA Penny shown for reference.

Edit: Added link to corrected data sheet (obtained from dpcav.com site)

post-15-1165030955_thumb.jpg

Edited by Mr.RC-Cam

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How many do you have? I might be interested in one as a future project to play with.

Oh, is it WAAS enabled? And how much does it weigh?

Edited by twinturbostang

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I have several , but I don't expect them to last long at this price. Get 'em while you can. :)

WAAS enabled, 15 grams.

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I want to get a small GPS unit that can be connected to a video overlay so I can see the data on screen at the ground station. Will this unit be suitable for this purpose? What additionaly items will I need in order to hook up the video overlay? Thanks.

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How can I get one of these cheap ones for speed and battery voltage only for an rc car?

The EM-411 does not provide video. It is a GPS module that sends the required NMEA sentence with global coordinates.

What additional items will I need in order to hook up the video overlay? Thanks.

You'll need a video overlay board that accepts GPS NMEA data. If the one you choose requires standard RS-232 voltages (inverted +/- 12V levels) then you will need something like a MAX232 IC to convert the 3V TTL from the EM-411 to those levels.

As mentioned, this GPS will work with the "Inspire" Video OSD board (it uses the same connector). But, a simple mod is required to adapt the GPS's signal order to the Inspire system. At the micro-GPS connector cable end, just swap the GPS's Tx and Rx signals (pins 3 & 4). The pins easily come out of the housing if you carefully lift the plastic tongues. Other GPS OSD boards may be as simple to interface, but I suspect that some will require the MAX232 IC.

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I forgot to add. Will this unit show a current compass heading?

For instance, I reckon if I know my groundstation coordinates and can read the current gps coordinates, I can quickly calculate a compass heading for straight line horizontal return to ground station.

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While it is moving, it will provide useful travel direction in TRUE North degrees. Basically, it provides the standard NMEA-183 data (GGA, GSA, GSV, RRMC sentences).

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EM-411 SiRF III Command Set Doc

http://www.usglobalsat.com/downloads/SiRF_...ry_Protocol.pdf

EM-411 Connector Info

EM-411 Female Cable Connector: Digi-Key Part No: 455-1381-ND

EM-411 Male PCB Header: Digi-Key Part No: 455-1424-1-ND

Extremely cool and low cost Waypoint Engine Project that can be used with the EM-411:

http://www.rcgroups.com/forums/showthread.php?t=515929

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At this point, only five of these beauties are available.

If you thinking about creating a GPS based aerial system, then this is a nice module to use. They just don't get any smaller at this price! And because it is one of the rare modules that can obtain a satellite lock indoors, it is much easier to test your project on the shop's indoor workbench.

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Received mine, they are TINY indeed! The smallest ones I've seen with integrated antenna :)

Thanks ;)

Edited by Kilrah

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I have a question...

Is it possible to plug directly (with a cable adapter of course) into the serial port of a laptop? I was thinking this would be the easiest way to do some preliminary testing with it.

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The outputs are designed for direct connection to a microcontroller. To connect to a PC, you would need a TTL to RS-232 interface. The Maxim MAX232 is popular.

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I sold out all the EM-411's modules today. However, I have a small number of them on their way, so if you want one of them, PM me fast. I understand the well will be dry after they are gone.

Also, I have a EM-401 SiRF II GPS module for sale:

http://www.rc-cam.com/forum/index.php?act=...=ST&f=15&t=1575

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I have a small number of EM-411's remaining From the batch that I received yesterday morning. I don't plan on repeating the deal, so keep that in mind. Prices remain as before.

For those that have bought one and tried it, what do you think of it?

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I have a small number of EM-411's remaining From the batch that I received yesterday morning. I don't plan on repeating the deal, so keep that in mind. Prices remain as before.

For those that have bought one and tried it, what do you think of it?

What do I think?

Well. It s really small and lightweight. What elese? It works great and everything is just OK, exactly as expected. It wasn't very difficult in hooking up and interfacing.

It's quite cloudy these days in Poland so it wasn't very eager to get a fix on a windowsill, but taken outdoors to get a fix and brought back onto the same windowsill it kept providing good data for several hours.

I haven't performed any in-flight tests yet.

Anyway I am very satisfied with this little thingy.

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Just wired the first of them to a TL100 board, works like a charm :)

However, are you sure they are EM411's? I've initially wired it like the datasheet you posted at the beginning of the thread, only to see nothing was happening. I took out the scope, and quickly saw the TX and RX pins were swapped, like they should be on the EM406... :unsure:

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On the EM-411 data sheet, the pin descriptions on Page 5 are correct. However, the Pinout drawing on Page 7 is wrong (they show the EM-406 pinout). On the EM-411, Tx (GPS data out) is pin 3. What pin are you using?

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-AT-Mr.RC-Cam:

Do you still have the EM411's on stock, or are they sold out?

I would be very interestd to get one of them.

Cheers,

Hartwig

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