Stamp control of cell phone text message

stamptrol

Program, schematic and write up attached to last post.


**Update** I have a solution on my PDB that I'm going to explore further. Using a standard, unmodified cell phone set to auto-answer and using the earphone jack, I put that signal into a dtmf decoder which the Stamp can read. In operation, you dial the cell phone number, wait until it auto-answers then press various buttons on the calling phone. Those tones get decoded and presented to the Stamp.
The Stamp can give confirmation to the caller by beeping a speaker.....but not in Morse code as one example on Youtube shows!

Will post the working code as I refine it.



Hi folks,

What I want to do is use a Stamp-based monitoring system to automatically send one of several text messages, depending on alarm conditions. The site is floating in the middle of the river.

I had thought serial control of the phone's functions could be done, but it seems that type of connection (also Bluetooth) is for specific links such as headset, contacts list, pics, etc.

At the moment, I'm considering paralleling the keypad switches as necessary to allow the Stamp to "push the buttons" to select the correct pre-set message to be sent to the last number dialed..

I'm also testing the use of DTMF tones to operate the phone like we used to do with the landlines in phreaking days. No problem generating the tones with the Stamp. And, the tone decoder works fine. Have to do a bit more work on coupling tone to phone.

Looking for any thoughts, alternatives or suggestions.

Thanks,
Tom

tobdec

This solution sounds just like something I would do...however there is one big issue....with not communicateing directly with the phones serial how do you know if the txt was sent or not? I can't tell you how myabe times my phone for no reason will not send a txt.

tobdec

Actualy I think I know exactly how to solve this...most phones will output a dedicated tone when a txt has failed to send. You could use this tone as a trigger to resend the txt.

Franklin

Something like this http://www.sparkfun.com/products/9427 might be helpful.

Duane Degn

stamptrol wrote: »

And, the tone decoder works fine. Have to do a bit more work on coupling tone to phone.

When I was researching something like this, I found a post by Cluso99 warning against connecting a uC to the phone line.

I think the cell phone option is a safer route than using a land line.

Gadgetman

Most modern phones doesn't have a serial port, and exactly what they're doing on BT is anybodys guess...

There are dedicated 'GSM modems' for sale, but most of those are more expensive than the Sparkfun board, so I would go with that.
But first download the AT command code PDF on that site. Quite interesting reading.
(I once built an 'almost complete' SMS system for my old Nokia 2110 phone using macros in the Terminal emulator on my Psion S3a PDA. Just couldn't figure out a good way to store the received messages)

stamptrol

Hello, all

Thanks for the responses.

I've found two possibilities which I'm testing over the next couple of days.

The first (thanks to Youtube) makes use of most mobiles' ability to auto-answer at which point I can get a tone decoder involved to listen to touch-tones from the requesting end.

The second is to set the phone to TTY mode and use the low speed Baudot out of the headset jack.

I'll report on any progress.

Cheers,

Tom

Erik Friesen

I purchased a gophone lately, and find that it is capable of at commands through the usb port, set up as cdc acm. I am using a pic32 for this, I suppose it could be done with the prop + max??.

stamptrol

Erik,

I'd be interested in your PIC32 setup.

Cheers

LoopyByteloose

Here is another alternative for a serial link to a cellular telephone - IR.
I had a rather expensive 3G Nokia that would accept SMS messages composed on my Palm PDA via an IR link. I was actually very fond of the function and regret that the Nokia was damaged. My new phone did not have such a feature.

Brian Carpenter

there is an object in the OBEX to do this with the prop
I have used it with great success

LoopyByteloose

I still think locating an IRDA cellular telephone would make this whole project easier.

http://tldp.org/HOWTO/html_single/Infrared-HOWTO/

http://reviews.cnet.com/cell-phone-reviews/?filter=501637_101528_

stamptrol

To finalize this little project I have attached the schematic, the program code and a short write up.

Cheers,