Propeller Cell Dialer/Texter

[Duane Degn]

I've been working on a project to help elderly people summon help.

I initially considered adding a connection to the phone-line so the panic buttons could make outside calls.

After a bit of research I learned (mostly from Cluso99) phone line hacking is a bad idea.

I know there are modules for connecting a cell phone to a microcontroller but I didn't want to spend that much money.

I had an extra cheap cell phone. I opened it up to see if I could hack it.



The keypad uses some sort of matrix to scan the buttons. They weren't laid out in columns and rows but I was able to find eight independent traces. By shorting two of the eight traces together a button-press was register. The power button had its own trace that needed to be shorted to ground to activate.

As you can see in the above photo, I soldered wires to these traces.

I used one relay for the power button. An additional eight relays let the Propeller simulate any key-press on the keypad.



I decided I wanted to be able to still press the buttons on the cell phone so I rigged up an alternate keypad. The alternate keypad is in the upper right of the photo above.

So far the Prop is able to send text messages that are stored in the DAT section of the program.

I've added keyboard and TV support so I will be able to (soon) type text messages with a computer keyboard or in a terminal window from the computer.

It's pretty cool to listen to the relays clicking away at 10 clicks per second as it enters the text message. I tried increasing the rate of button-presses but I found 10 Hz was the phones limit.

I was going to wait until I had everything working before posting this project. I decided to post it now because there have been several references to cell phone use on the forum lately. Hopefully this will make it easier to use a cell phone with the Prop without having to buy an expensive module.

A big draw back with this method is it is send only. I don't have a way of transferring data from the cell phone to the Propeller.

I'll post the code once I finish adding (working) keyboard support.

Duane

[Duane Degn]

Reserved for code.

[Duane Degn]

Reserved for connector information.

[Peter Jakacki]

You don't need relays to do this as you can write software to sense when the column is being scanned and then at the same instance output the active condition onto the row. So assuming that interface voltages are compatible you can do this directly from the Prop's I/O and maybe just insert some current limit resistors of say around 220R or so.

So it's not as cool as having a bunch of relays clicking but it's a lot simpler.

[Duane Degn]

You don't need relays to do this as you can write software to sense when the column is being scanned and then at the same instance output the active condition onto the row. So assuming that interface voltages are compatible you can do this directly from the Prop's I/O and maybe just insert some current limit resistors of say around 220R or so.

Peter, that's a very good idea. I hadn't even thought to try it.

I haven't looked at the pads with an oscilloscope. The voltage on each pad reads a constant (on my DMM) 1.7 V. I bet you're right, it is reading a lower voltage because of the scanning. I could measure the current across two pads to figure out the appropriate resistor value.

So it's not as cool as having a bunch of relays clicking but it's a lot simpler.

I don't know if I could give up the clicking relays. They sound so cool!

It's great fun to watch and listen as the Prop makes multiple key-presses for each character of the text.

Duane

[Crosswinds]

Hello!

May i just give an idea for this!


I have for some time been working on an idea for a fish-tank survelliance system. That could send alerts via GSM Text.

I found that the most simple easy and cheap way is to buy an old nokia 6210/6310 from ebay. And the nokia RS-232 cable.

These great phones can send and recieve Text ( think also calls) Via simple serial commands. Its real real simple.

Its worth looking in too, since its very reliable also.

[Duane Degn]

@Crosswinds,

I've been looking at some of the Nokia phones on ebay. I see a lot of 6310i phones. Do you know if the "i" phones also have the serial connection?

Are you able to use a Propeller chip to send and receive automated text messages through your Nokia phone?

This is a good idea. I think the phone will be cheaper than a cell module from SparkFun.

Thanks,

Duane

[lfreeze]

Take a look at the thread titled "motorola c16i cell phone and adapter" I downloaded and modified Jays code for
an alarm system project. I got the motorola cell phone on ebay for $10.00. I think this may be a solution you
can use without additional hardware.

Larry

[Crosswinds]

@Crosswinds,

I've been looking at some of the Nokia phones on ebay. I see a lot of 6310i phones. Do you know if the "i" phones also have the serial connection?

Are you able to use a Propeller chip to send and receive automated text messages through your Nokia phone?

This is a good idea. I think the phone will be cheaper than a cell module from SparkFun.

Thanks,

Duane

Hello Duane!

Yep! The 6310i also works. (Its actually alot of phones from nokia that are compatible with this) The 6310i is the latest and most advanced phone that still support the rs-232 AT commands.

I do have a printed manual from nokia that explaines how to use the AT commands (and there are alot of fun functions!). I can scan that for you if you want?

A tip is to look at "refurbished" phones from china on ebay. They mount new (not original i guess) front and backs on them and sell them as "refurbished" phones. Those are VERY cheap and they are many.


The prop works very well with serial communication. And the cable you need is also all over ebay.

I think that this is a good solution for reliable functionality!

[Duane Degn]

Crosswinds,

Thank you for the additional information. This is a really good idea.

Do you know if I should avoid the "UK" versions? There seems to be a lot of them. I'm guessing they wouldn't work with my carrier (T-Mobile).

Agree with your "refurbished" suggestion. I don't think I care much about the cosmetics of the phone.

Duane

[Crosswinds]

Crosswinds,

Thank you for the additional information. This is a really good idea.

Do you know if I should avoid the "UK" versions? There seems to be a lot of them. I'm guessing they wouldn't work with my carrier (T-Mobile).

Agree with your "refurbished" suggestion. I don't think I care much about the cosmetics of the phone.

Duane

Yeah this is real exciting!

Just think of what you could to with the propellers easy way to incorporate a keyboard to this? A better SMS terminal is hard to find!

I cant answer for the UK phones, as im in Sweden. But as of what i remember the 6310i is a world phone. It do use a SIM-card. A pre-paid plan would be the best system for this right?


The china-phones are good and cheap, and they atleast looks okey and are tested!

[max72]

I'm testing the SIM900, and sending receiving SMS is extremely intuitive.
It uses serial protocol.
In Italy there is a seller shipping the modules assembled with SIM/antenna holders and some passives.
http://www.futurashop.it/allegato/81...0&nVt=&d=51,00
Not so cheap but works out of the box.. Only problem is voltage/current supply, as it has big current bursts..
Massimo

[erco]

I don't know if I could give up the clicking relays. They sound so cool!

It's great fun to watch and listen as the Prop makes multiple key-presses for each character of the text.

Duane

I agree! Many have been seduced by the electromechanical sounds of relays activating, even way back in the 1960's show "Lost in Space":

"The fembot returns tinkling. Smith screams as he finally realizes it is her. "William!" Trapped, Smith tries to con her calling her silvery tinkling of computer relays quite nice." from http://gallifreyanembassy.org/vortex/node/904