I plan to drive a C55 siemens GSM phone with a pic. The phone is under 3,6 volt, is it necessary to respect this voltage when communicating in RS232 and make run the pic in less than 4 volts ?
If anyone have experience about this, thanks to help.
I´m using a max232 at 4,3V as interface, but the pic is running at 5V.
really use 2 max232, 1 in the motherboard (also used for the bootloader) and the other as the interface for the siemens so the signal pass trought the 2 IC´s to the phone
the best solution is to use the 3.3 version of max232.
Thanks for the tips. I've found how to do with a 232 and it works well now.
Actually I'm experimenting communications with the phone and a Pic 16F873 and a basic compiler.
All is working as I want but I found difficulties to build SMS in basic because the C55 doesn't work in text mode for SMS but only in PDU mode wich is quite more difficult.
Have you try this ?
Do you think that if communication works with a C55 it does work with others cellular modem equiped ?
If you have pin description for C55 (and I uppose it i not big problem to find serch siemens site or ask their support team ) you can use this primitive schema .
im using nokia 3310 for the same application. i dont want to use the
microcontroller in between but want to retreive the received messages directly to the VB program which is running in a PC. i struct up with the embedding the AT commads in the VB program and also retrieving the entire received messages in the VB application itself.
hi,
let me tell you that nokia 3310 didn't support the at commands (it use a protocol called (f-bus)
here you will find a lot of inf about that :
**broken link removed**
if you want to use at commands with nokia phones using pc only (not embedded)try to use nokia data suite
Search the sourceforge.net there are ready to use library and soft for SMS sending adapted for different phone types and different alphabet . If I am not wrong project was written in C++ , but may be new projects are added to support VB as well .