Multitech GSM Modem

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Multitech GSM Modem

Postby comp850 » Mon Mar 09, 2009 11:02 pm

I tried a couple of months ago to incoporate a multitech GSM modem (such as...http://mouser.com/Search/ProductDetail.aspx?qs=sGAEpiMZZMuGqqSvxcmxwuNQh8xtHvDj). Did the whole line level converter and such. However it didn't work. I don't think the line level converter is broken. On a recent project, I learned that the GSM modem doesn't use inverted serial logic. Is there a way to convert the serial logic from "true" to inverted?
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Re: Multitech GSM Modem

Postby Mike » Tue Mar 10, 2009 7:31 am

If the modem uses RS-232 levels, then you need a MAX3232 chip. The MAX3232 does invert the signal as well as change the levels.

Mike
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Re: Multitech GSM Modem

Postby Mike » Sat Mar 14, 2009 2:49 am

Did you ever get this to work?

If you loan me the modem, I will add support to the software.

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Re: Multitech GSM Modem

Postby comp850 » Tue Mar 17, 2009 5:34 am

I haven't gotten it to work...

I am currently using a Basic Stamp 2 to interface with the modem. For the SERIN, SEROUT commands, I have to use the non-inverted serial communication. When hooking up the Garmin GPS directly to the stamp, I use the inverted serial communication. Now, when I run the Garmin GPS through the MAX3232 line level converter, I have to change the BS2 programing to non-inverted serial communication.

Sure, I could loan you the modem. Could you PM me?


Mike wrote:Did you ever get this to work?

If you loan me the modem, I will add support to the software.

Mike
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Re: Multitech GSM Modem

Postby comp850 » Fri Apr 03, 2009 3:09 am

Just curious on how things are going with the Multitech Modem.
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Re: Multitech GSM Modem

Postby comp850 » Sat Dec 12, 2009 10:12 pm

For those interested...

Image


Will be selling PCBs in the near future (Note this isn't the final design)...

Features:
    ATTiny84/ATMEGA88 Support
    DB9 and RJ45 GPS (RJ45 Pinned out for the Garmin GPS16x)
    The RJ45 GPS can be run off of either raw incoming power or 5volts (regulated)
    The Car Security Option on a 2x5 header (with pcb to follow)
    Uses the MTSMC-G-F4 Socket Modem
    Uses a Level Converter
comp850
 
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Re: Multitech GSM Modem

Postby comp850 » Wed Mar 17, 2010 4:33 am

Got a pict of the prototype Car Security board.

Image
Image

Should have the boards for both by mid to late April.

Updated Specs for the Tracker Board:
    ATtiny84/ATmega88 Support
    Car Security Board hookup (as pictured above)
    RJ45 GPS can run off either raw incoming power or regulated 5volts
    DB9 or RJ45 (RJ45 Pinned out for the GPS16x or compatible)
    Debug through DB9 (and level converter)
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Re: Multitech GSM Modem

Postby comp850 » Wed May 12, 2010 3:38 am

Boards can be purchased by going to the following link... Free registration is required...
http://www.batchpcb.com/index.php/Products/30703

Some information about about the board can be found by going to the following link.
http://www.minionmultimedia.com/car-tracker.html
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