User's Manual

GC864 Hardware User Guide
1vv0300733 Rev. 0 - 12/06/06
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Right reserved page 2 of 68
Contents
1 Overview ...........................................................................................................................4
2 Hardware Commands ......................................................................................................5
2.1 Turning ON the GC864 ...........................................................................................................5
2.2 Turning OFF the GC864 ........................................................................................................7
2.2.1 Hardware shutdown..........................................................................................................................7
2.3 Hardware Unconditional Reboot...........................................................................................7
3 Power Supply ...................................................................................................................9
3.1 Power Supply Requirements.................................................................................................9
3.2 General Design Rules ..........................................................................................................10
3.2.1 Electrical design Guidelines........................................................................................................... 10
3.2.1.1 + 5V input Source Power Supply Design Guidelines ................................................................ 10
3.2.1.2 + 12V input Source Power Supply Design Guidelines .............................................................. 12
3.2.1.3 Battery Source Power Supply Design Guidelines ..................................................................... 13
3.2.1.4 Battery Charge control Circuitry Design Guidelines .................................................................. 13
3.2.2 Thermal Design Guidelines ........................................................................................................... 15
3.2.3 Power Supply PCB layout Guidelines ........................................................................................... 16
4 Antenna...........................................................................................................................17
4.1 Antenna Requirements ........................................................................................................17
4.2 GC864 Antenna Connector..................................................................................................17
4.3 Antenna installation Guidelines..........................................................................................18
5 GC864 pins allocation....................................................................................................19
NOTE: RESERVED pins must not be connected..........................................................................21
6 Serial Port .......................................................................................................................22
6.1 RS232 level translation ........................................................................................................24
6.2 5V UART level translation....................................................................................................26
7 Audio Section Overview ................................................................................................28
7.1 Microphone paths characteristic and requirements .........................................................30
7.2 General Design Rules ..........................................................................................................33
7.3 Other considerations. ..........................................................................................................33
7.4 Microphone Biasing .............................................................................................................34
7.4.1 Balanced Microphone biasing........................................................................................................ 34
7.4.2 Unbalanced Microphone biasing ...................................................................................................35