Telit Wireless Solutions GM862-GPS Manuel D’Utilisation
GM862-GPS Hardware User Guide
1vv0300728 Rev. 0 - 27/04/06
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Right reserved
page 2 of 55
Contents
1 Overview ...........................................................................................................................4
2 Hardware Commands ......................................................................................................5
2 Hardware Commands ......................................................................................................5
2.1
Turning ON the GM862-GPS..................................................................................................5
2.2
Turning OFF the GM862-GPS ................................................................................................7
2.2.1
Hardware shutdown..........................................................................................................................7
2.2.2
Hardware Unconditional Reboot.......................................................................................................8
3 Power Supply .................................................................................................................10
3.1
Power Supply Requirements...............................................................................................10
3.2
General Design Rules ..........................................................................................................11
3.2.1
Electrical design Guidelines........................................................................................................... 11
3.2.1.1
+ 5V input Source Power Supply Design Guidelines ................................................................ 11
3.2.1.2
+ 12V input Source Power Supply Design Guidelines .............................................................. 13
3.2.1.3
Battery Source Power Supply Design Guidelines ..................................................................... 14
3.2.1.4
Battery Charge control Circuitry Design Guidelines .................................................................. 15
3.2.2
Thermal Design Guidelines ........................................................................................................... 17
3.2.3
Power Supply PCB layout Guidelines ........................................................................................... 18
4 Serial Ports .....................................................................................................................19
4.1
level translation ....................................................................................................................21
4.2
5V UART level translation....................................................................................................23
5 Audio Section Overview ................................................................................................25
5.1
Microphone paths characteristic and requirements .........................................................27
5.2
General Design Rules ..........................................................................................................30
5.3
Other considerations . .........................................................................................................30
5.4
Microphone Biasing .............................................................................................................31
5.4.1
Balanced Microphone biasing........................................................................................................ 31
5.4.2
Unbalanced Microphone biasing ................................................................................................... 32
5.5
Microphone buffering...........................................................................................................34
5.5.1
Buffered Balanced Mic................................................................................................................... 34
5.5.2
Buffered Unbalanced (Single Ended) Microphone . ...................................................................... 36
6 OUTPUT LINES (Speaker)..............................................................................................39
6.1
Short description..................................................................................................................39
6.2
Output lines characteristics . .............................................................................................40
6.3
General Design rules............................................................................................................41