SIM900D Hardware Design
Contents
Contents .....................................................................................................................................................................3
Version history...........................................................................................................................................................7
1 Introduction.............................................................................................................................................................8
1.1 Related Documents .......................................................................................................................................8
1.2 Terms and Abbreviations...............................................................................................................................9
1.3 Safety Precautions.......................................................................................................................................11
2.1 SIM900D Key Features...............................................................................................................................13
2.2 SIM900D Functional Diagram....................................................................................................................15
2.3 SIM900D Evaluation Board........................................................................................................................16
3.1 SIM900D Pin Description...........................................................................................................................18
3.2 Operating Modes.........................................................................................................................................21
3.3 Power Supply ..............................................................................................................................................22
3.3.1 Power Supply Pins.............................................................................................................................23
3.3.2 Minimizing Power Losses .................................................................................................................23
3.3.3 Monitoring Power Supply .................................................................................................................24
3.4.1 Turn on SIM900D .............................................................................................................................24
3.4.2 Turn Off SIM900D............................................................................................................................26
3.4.3 Restart SIM900D Using the PWRKEY Pin ......................................................................................28
3.5.1 Battery pack characteristics...............................................................................................................29
3.5.2 Recommended battery pack ..............................................................................................................30
3.5.3 Implemented charging technique.......................................................................................................30
3.5.4 Operating modes during charging .....................................................................................................31
3.5.5 Charger requirements ........................................................................................................................32
3.7 Summary of State Transitions (except SLEEP mode).................................................................................33
3.8 RTC Backup ................................................................................................................................................34
3.9 Serial Interfaces...........................................................................................................................................36
3.9.1 Function of serial port & debug port supporting ...............................................................................37
3.9.2 Software Upgrade and Software Debug ............................................................................................38
3.10.1 Speaker Interface Configuration......................................................................................................41
3.10.2 Microphone Interfaces Configuration .............................................................................................42
SIM900D_HD_V1.02
09.04.2010
3
