Mobile Phone home-made UART cables connected to PC

[lloydi12345]

Hi Electro-tech-online. I am back to ask help again about my newest project. The project is all about using a mobile phone as a substitute for RF Transceiver Modules. The user should be able to control some appliances using only mobile phones. When the user sends a text message by his mobile phone to another phone, the other phone will then check the data received. The mobile phone then sends command to the microcontroller to do such task. I don't have problem with programming the microcontroller since I already know it. I am still searching informations about AT commands since I think AT commands will be mostly utilized.

The first thing I have thought was to try if everything works on my desktop computer. I would try first connecting the UART pins of the mobile phone to a MAX232 to be connected to the Computer. Through hyperterminal, I will send data then the mobile phone should respond properly.

I don't know yet the cheapest mobile phone that has a UART tx, rx and gnd pin. Perhaps 8210? or what else do you think? I am thinking also what if I'll use mobile phones which has the USB cable then I'll just cut them and find which one is the tx, rx and gnd pin. Can you add more some tips on how to build this project? Any replies will be much appreciated

Regards,

lloydi

 

[blueroomelectronics]

USB phone won't work with RS232. You need a phone with an RS232 connector.

 

[House0Fwax]

what if I'll use mobile phones which has the USB cable then I'll just cut them and find which one is the tx, rx and gnd pin.

I have done exactly that with a USB data lead for a Sharp GX10 / GX20. The USB plug end (which is a lot bigger than a standard USB 'A' plug) contains the necessary USB to RS232 converter. Having removed it I was able to find the right combination and have used it with Hyperterminal and indeed a 16F628. I only had to add two pull-up resistors and ground another of the wires.

Having said that, suddenly it doesn't work with the Pic, though it does with Hyperterminal. I'll be looking at it over the coming weekend.

 

[KeepItSimpleStupid]

This is a totally wierd question. Phones have USB ports. Some phones such as Android based allow applications to be developed for the phone. Installing those applications for the average consumer will probably be tricky though.
So if I'm reading you right, you would say have an app on the Android based phone and connect it to something via it's USB port.

Someone makes a plug in IRDA device for the iphone.

Some phones like the Motorola V3, V3xx allow access to the GPRS modem through the USB connector which responds to AT commands. I have played with this mechanism successfully.

 

[blueroomelectronics]

I was under the impression the OP wants to use a cell phone as a modem.

 

[KeepItSimpleStupid]

I couldn't figure out what the OP wanted. I have no idea what "home made" means.

Certain cell phones can be used as a modem easily, others cannot.

I did modify the modem scripts for an old apple ibook running OS9 and a Motorola Razr V3. It also worked fine under a terminal emulation program.

 

[Nigel Goodwin]

This is a totally wierd question. Phones have USB ports.

A lot of the older phones came with a USB lead, but only had serial ports on the phone - the USB/Serial converter is in the lead.

As House0Fwax said, it's possible to cut the lead and use it just as a 5V serial lead - you can always use the other half as a USB/Serial converter as well.

 

[lloydi12345]

Hi thank you for your helpful replies. Sorry for all the confusions. What I mean on "home-made" cables was, soldering the rx, tx and gnd pin of the CHEAP mobile phones through jumper wires then just connect them to the max232 that is connected to the rs232 of the computer.

The USB data cable was another option which I'm not yet so sure if there are really rx, tx and gnd pin in it since it is desired to be connected to the USB port. But of course I don't know if the cellphones that I'll be using here are cheap.

I don't know which is the better option