Shop OBEX P1 Docs P2 Docs Learn Events
Interfacing a Prop with a CDMA cell phone — Parallax Forums

Interfacing a Prop with a CDMA cell phone

JonathanJonathan Posts: 1,023
edited 2008-12-03 02:42 in Propeller 1
Hi All,

Since this question doesn't really fit into the previous thread about the Motorola cell phone, I thought I'd start a new thread, hope that is OK.

I'm trying to get a Kyocera K126C to talk to a Prop for a remote alarm system. This guy keeps breaking through the gate of my remote property and stealing logs, cutting down trees and wrecking my road. The sherrif says I need to catch him in the act, hence the remote alarm.

Working with Jay's code and my own, I find the following:

The phone will echo anything I send to it, up to 28.8 baud. After that it hangs.
It always reflects only what I send it, I never see an "OK" or anything other than what I send it.
It doesn't matter if I idle high or low, it always echos.
It doesn't matter which pin I set as in or out, it always echos.
The echos have no delay that I can see using my Parallax scope, I guess it's too slow.

I am using the headphone plug like Jay.

I would give up, except that it seems like I must be getting *something* going, since it only echos up to 28.8 baud and then hangs. Perhaps this phone doesn't do modem commands. I have looked and looked, have called Kyocera and can't find anything about the phone. The only thing I see is that one can buy a comm cable for it to retrieve contacts and ringtones. While I can't find a picture of one, it must go in the headphone jack, as there is no other port.

And, the dang thing uses a tri-screw, which I don't have a screwdriver for. If I can get it apart, perhaps I can interface directly with the keypad using transistors.

TIA,

Jonathan

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
www.madlabs.info - Home of the Hydrogen Fuel Cell Robot

Comments

  • Jay KickliterJay Kickliter Posts: 446
    edited 2008-12-02 18:11
    If it is echoing but not sending any "ok"s it might just be looping back. As in there the send and recv pins on the connector are electrically connected. I'd first check the resistance in the cable between the send and receive unplugged, and then again when it is plugged in. This happened to me because of a sloppy solder job in the connector.
  • Jay KickliterJay Kickliter Posts: 446
    edited 2008-12-02 19:52
    I was thinking, the reason it might be cutting out above 28800 baud is the impedance is going up with frequency. I have no idea the of what the internals are though.
  • john_sjohn_s Posts: 369
    edited 2008-12-02 22:46
    Jonathan,

    Perhaps Kyocera K126c does NOT support AT commands at all and the headphone jack is for TTY use only (see Kyocera's manual and link below)?

    http://www.t-mobile.com/Company/Community.aspx?tp=Abt_Tab_Safety&tsp=Abt_Sub_TTYPolicy

    From what you described I suspect that the TTY/headset jack somehow jumpers both Tx and Rx signal paths, so when you type AT you gonna see the echoed AT back and duplicated as AATT - am I correct? The same you can observe when connecting together Tip and Ring of your "communication" headphone plug·smile.gif

    Post Edited (john_s) : 12/2/2008 10:52:56 PM GMT
  • JonathanJonathan Posts: 1,023
    edited 2008-12-02 23:26
    Methinks you are right, I came to the same conclusion. It still puzzles me why it would hang above 28.8k baud though. I decided to go the dumb guy route, I pulled it apart and hacked into the keypad, using an NPN transistor, works fine. But boy do I have some soldering ahead of me. [noparse]:([/noparse]

    Jay, no continuity between RX/TX on the cable, so that part was OK. I just don't think it does it. Of course, I'll find out it can after I solder up all the bloody transistor and write klunky macro style code to send messages. :0 But hey, if I catch the guy, I'll be well pleased.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    www.madlabs.info - Home of the Hydrogen Fuel Cell Robot
  • Jay KickliterJay Kickliter Posts: 446
    edited 2008-12-03 00:54
    How far away do you need to transmit? Is it too far for one of these RF modems?


    www.sparkfun.com/commerce/product_info.php?products_id=560
  • SRLMSRLM Posts: 5,045
    edited 2008-12-03 01:33
    Sparkfun has another modem that goes an additional 500m, if that helps... Anyway, why exactly are you using a cell-phone? What sort of evidence do you need? You could hook up a camera to the propeller, and have it motion activated. You can probably get his face and license plate then.
  • JonathanJonathan Posts: 1,023
    edited 2008-12-03 02:19
    Well, I did it the dumb guy way, but it works. I simply soldered wires to the key pad, and with transitors can switch the kepad. Only needed 4 buttons to send a text message to anyone in the contact group. While there is no subject or message, I'll know that any text from that number is a dirtbag incursion. Of course, this has no smart capabilities, but it will suit the purpose well enough.

    The property is located about 2 miles away from where I live. I could have done a modem, but the phone and airtime were around $25, so this is a cheap way to go. Don't want a camera, he works at night mostly and he would see the flash. Just knowing that he has gone through the gate is enough, I'll go and block the driveway with my truck and call the sheriff.

    Now to get it all in a waterproof container and catch me a dirtbag! This guy has cost me a lot (to me) of money, and also started a fire on a nearby property, so I sooooo hope he tries it again!

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    www.madlabs.info - Home of the Hydrogen Fuel Cell Robot
  • Brian CarpenterBrian Carpenter Posts: 728
    edited 2008-12-03 02:40
    Jonathan,
    Please let us know how the hunt goes.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔


    It's Only A Stupid Question If You Have Not Googled It First!!
  • SRLMSRLM Posts: 5,045
    edited 2008-12-03 02:42
    When you catch him, be sure to put it in the completed projects forum [noparse]:)[/noparse]
Sign In or Register to comment.