User's Manual

Telit GE863-GPS
Hardware User guide
1vv0300714, Rev. ISSUE#0, - 21/02/06
Reproduction forbidden without Telit Communication written authorization – All Right reserved – Right of modification reserved page 3 of 76
5 SERIAL PORTS 24
5.1 MODEM SERIAL PORT 24
5.2 MODEM SERIAL PORT 2 (GPS CONTROL) 26
5.3 GPS SERIAL PORT A (SIRF BINARY) 26
5.4 GPS SERIAL PORT B (NMEA) 27
5.5 RS232 level translation 27
5.6 5V UART level translation 30
6 MICROPHONE 32
6.1 Microphone line Characteristic and requirements 32
6.2 General Design Rules 35
6.3 Microphone Biasing 35
6.3.1 Balanced Microphone biasing 36
6.3.2 Unbalanced Microphone biasing 38
6.4 Microphone buffering 39
6.4.1 Buffered Balanced Mic. 39
6.4.2 Buffered Unbalanced (Single Ended) Mic. 42
7 SPEAKER 45
7.1 Speaker lines characteristics and requirements 45
7.2 General Design rules 47
7.2.1 Noise Filtering 48
7.3 Handset earphone design 48
7.4 Hands Free earphone (low power) design 50
7.5 Car Kit speakerphone design 50
8 GENERAL PURPOSE I/O 52
8.1 Using a GPIO pad as INPUT 52
8.2 Using a GPIO pad as OUTPUT 52