GE863-PRO3 Hardware User Guide
1vv0300773a Rev. 0 - 24/01/08
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights Reserved page 39 of 64
The serial port on the Telit GE863-PRO3 is the core of the interface between the module engine and
the ARM processor.
2 serial ports are available on the module engine:
• MODEM SERIAL PORT
• MODEM SERIAL PORT 2 (DEBUG)
6+1(DBG) serial ports are available on the ARM part.
No direct connection is present between the two parts, on the hosting PCB the two serial ports need to
be interconnected. It is up to the user to select whatever serial port is most suited on the ARM part to
exchange data with the GSM/GPRS engine; however the USART0 port on the ARM is the only
supporting the full RS232 line signaling and should be preferred.
In the ball-out of the GE863-PRO3 the balls of the MODEM SERIAL port and ARM USART0 are
placed one next the other, allowing an easy routing of the connection.
7.1 MODEM SERIAL PORT
Several configurations can be designed for the serial port on the OEM hardware, but the most
common are:
• RS232 PC com port
• microcontroller UART @ 2.8V – 3.1V (Universal Asynchronous Receive Transmit)
Depending from the type of serial port on the OEM hardware a level translator circuit may be needed
to make the system work. The only configuration that doesn't need a level translation is the 2.8V –
3.1V UART and hence the GE863-PRO3 GSM/GPRS engine can be directly connected with the ARM
serial port @ 3.1V CMOS.
The serial port on the GE863-PRO3 GSM/GPRS engine is a +2.8V UART with all the 7 RS232 signals,
While the serial ports on the ARM part are +3.1V UART.
GE863-PRO3 serial ports differ from the PC-RS232 in the signal polarity (RS232 is reversed) and
levels.