Teensey 3.0 with GSM/GPRS interface?

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awardblvr

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One of my next projects is going to be interfacing an alarm system (HAI Omnipro 2) to a 'duino type controller and a GSM interface to do some texting, and possibly some other connection things (Doorbell rings, places voice call to my cell - two way audio from GPRS board to intercom system directly - audio not processed through 'duino.

I'm looking closely at:

GSM/GPRS Shield for Arduino (SIM900 module from SIMCOM) (ebay listing) - Actually I ordered one. ($38) or

GPRS/GSM Quadband Module for Arduino / Raspberry Pi (SIM900) from Spain, but available on Amazon for a too-high price of $114

BTW. I *think* telna ([url]http://www.telnamobile.com)[/URL] has the best deal on pay-as-you-go with long-expiration times on pre-paid accounts. I THINK these are the best bet for hobbyists... Open to suggestions.

Question for Paul & Co. Is this advisable? Is there a better solution. What is your preferred board / interface logic-level converter that you suggest to implement connections to a 5V board from a Teensy 3.0? Or do you recommend even doing this at all?

I've just run into so many problems with straight Arduino stuff (Pro-Mini 5V connected to MP3 Player Shield) with crappy libraries, even with your malloc fix, that I want to switch all my current and future projects over to Teensey 3.0 due to its speed and capacity.

Thanks for any advice!
 
Wow... my first post and no one seems able or interested to tackle it?? I was hoping to use Teensy 3.0 in several projects... perhaps not.

A lot of "views" so people ARE interested in interfacing to GSM/GPRS devices... I think there IS general interest. But does Paul or others think this is bad idea? Or, too insignificant to answer before I invest time/$ developing??
:(
 
I found the SIM900 chip tricky to use but workable re: GPRS connections. It's really neat how an entire cellphone is inside that enclosure. I had very good luck with the Seedstudio/Itead version of the shield and then rolled my own solution. One thing I found surprising is just how far some of the Seed/itead design decisions differed from the implementation tips given by simcom in their many (and sometimes conflicting) manuals.

I found GPRS communication to be very difficult to get working but finally succeeded. Using a standard shield allowed me to be sure it was the software that was faulty (vs. worrying that I'd messed up the hardware too). Used a EmbeddedWorks GSM card / chip.

Since proving the software, I rolled my own GPRS/Arduino combo board (328P MCU, RS485 receiver and Simcom stuff) so as to offload communicating with the GPRS network from the main processor (i.e. the master MCU sends the data via RS485 to the 328P slave on the GPRS board, the slave then works away at getting the data to the internet site of choice, and then later relays a successful signal back to the master MCU). It also helps ensure that if the MCU on the GPRS board hangs (as they apparently do) that the main MCU elsewhere can keep humming along.

As for interfacing to the Simcom, it operates at 2.8V on the serial side. So you will need a translator chip / solution, no matter what. I have found the TXB0106 to be an excellent chip to handle bidirectional traffic between the Arduino and the Simcom900. Most shields use the BSS138 mosfet approach popularized by (among others I am sure) Rocket Number Nine. The TXB also comes in a 8-channel version. HTH
 
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