Howto connect a PIC Microcontroller to a Telit GM862

In this project we connect the PIC microcontroller to the TELIT module by means of their UART peripherals. Due to different power supplies, we need to adapt PIC logic levels where a logic "1" is almost 5V to logic levels of the GSM module 2.8V at logic "1". With a NPN-PNP transistor couple we accomplish this result.