PIC16F877A and Siemens MC35i

Hi everybody,
I'm struggling with the issue of connecting my PIC (877A) to a gsm module, because of voltage levels difference.

I read some posts about connecting PICs to GSM cables, for which a MAX232 was useful to shift levels from the PIC's TTL to 12V for the cable input, where another level shifter embedded in the cable will behave as suitable for the mobile.

In my case, I should connect the PIC directly to the gsm module, whose lines work (I think) around 4.5V (max 4.8V), so I'm not sure that PIC's TTL logic could work, and a level shifter should be used to shift voltage for some 0.1V.
I'm not really sure of the mc35i voltage requirements because I could not find its datasheet, but a 2-page pdf brochure with the main electrical characteristics. I take the chance to ask if anybody has the mc35i's datasheet!!! (I need pinout as well...)

Hope that somebody could give me good news or some explanation!
Thanks,
francesco

francesco said:

In my case, I should connect the PIC directly to the gsm module, whose lines work (I think) around 4.5V (max 4.8V), so I'm not sure that PIC's TTL logic could work, and a level shifter should be used to shift voltage for some 0.1V.

Click to expand...

No need to do anything at that, it's well within the TTL/CMOS logic specification. If you really wanted to?, you could also power the PIC off the same 4.5/4.8V supply - but I don't see as it's required?.