
Smart Machine Smart Decision
SIM868_Series_Hardware_Design_V1.0672017-07-13
Figure Index
FIGURE 1: SIM868 BLOCK DIAGRAM ....................................................................................................................... 15
FIGURE 2: PIN OUT DIAGRAM (TOP VIEW) ............................................................................................................. 16
FIGURE 3: DIMENSIONS OF SIM868 (UNIT: MM) .................................................................................................... 19
FIGURE 4: RECOMMENDED PCB FOOTPRINT OUTLINE ...................................................................................... 20
FIGURE 5: RECOMMENDED SMT STENCIL FOOTPRINT OUTLINE .................................................................... 21
FIGURE 6: ALL-IN-ONE MODE DIAGRAM................................................................................................................ 22
FIGURE 7: STAND-ALONE MODE DIAGRAM .......................................................................................................... 23
FIGURE 8: REFERENCE CIRCUIT OF THE GSM_VBAT INPUT.............................................................................. 24
FIGURE 9: THE MINIMAL GSM_VBAT VOLTAGE REQUIREMENT AT GSM_VBAT DROP ............................... 24
FIGURE 10: REFERENCE CIRCUIT OF THE LDO POWER SUPPLY ....................................................................... 25
FIGURE 11: REFERENCE CIRCUIT OF THE DC-DC POWER SUPPLY ................................................................... 25
FIGURE 12: THE MINIMA L V B AT VOLTAGE REQUIREMENT AT VBAT DROP .................................................. 25
FIGURE 13: POWERED ON/OFF GSM USING TRANSISTOR .................................................................................. 26
FIGURE 14: POWERED ON/OFF GSM USING BUTTON........................................................................................... 26
FIGURE 15: TIMING OF POWER ON GSM ................................................................................................................. 26
FIGURE 16: TIMING OF POWER OFF GSM................................................................................................................ 27
FIGURE 17: TIMING OF RESTART GSM..................................................................................................................... 28
FIGURE 18: CONNECTION OF THE SERIAL INTERFACES ..................................................................................... 31
FIGURE 19: RESISTOR M AT C HI NG CIRCUIT ........................................................................................................... 31
FIGURE 20 : DIODE ISOLATION CIRCUIT................................................................................................................. 31
FIGURE 21: TX LEVEL MATCHING CIRCUIT ........................................................................................................... 32
FIGURE 22: RX LEVEL MATCHING CIRCUIT ........................................................................................................... 32
FIGURE 23: USB REFERENCE CIRCUIT .................................................................................................................... 32
FIGURE 24: CONNECTION FOR SOFTWARE UPGRADING.................................................................................... 33
FIGURE 25: UART1_RI BEHAVIOUR OF VOICE CALLING AS A RECEIVER ....................................................... 34
FIGURE 26: UART1_RI BEHAVIOUR OF URC OR RECEIVE SMS.......................................................................... 34
FIGURE 27: UART1_RI BEHAVIOUR AS A CALLER................................................................................................. 34
FIGURE 28: SPEAKER REFERENCE CIRCUIT .......................................................................................................... 35
FIGURE 29: MICROPHONE REFERENCE CIRCUIT .................................................................................................. 36
FIGURE 30: REFERENCE CIRCUIT OF THE 8-PIN SIM CARD HOLDER............................................................... 38
FIGURE 31: REFERENCE CIRCUIT OF THE 6-PIN SIM CARD HOLDER............................................................... 38
FIGURE 32: MOLEX 91228 SIM CARD HOLDER....................................................................................................... 39
FIGURE 33: AMPHENOL C707 10M006 512 SIM CARD HOLDER........................................................................... 40
FIGURE 34: SD REFERENCE CIRCUIT ....................................................................................................................... 41
FIGURE 35: REFERENCE CIRCUIT OF NETLIGHT................................................................................................... 42
FIGURE 36: RF_SYNC SIGNAL DURING TRANSMIT BURST ................................................................................ 43
FIGURE 37: GSM ANTENNA MATCHING CIRCUIT.................................................................................................. 44
FIGURE 38: GSM ANTENNA MATCHING CIRCUIT WITHOUT RF CONNECTOR ............................................... 44
FIGURE 39: BLUETOOTH ANTENNA MATCHING CIRCUIT .................................................................................. 45
FIGURE 40: REFERENCE CIRCUIT OF THE GPS_VB AT I N P U T ............................................................................. 47
FIGURE 41: RTC SUPPLY FROM RECHARGEABLE BATTERY .............................................................................. 48
FIGURE 42: RTC SUPPLY FROM EXTERNAL POWER ............................................................................................. 48
FIGURE 43: POWER ON/OFF GNSS............................................................................................................................. 49
FIGURE 44: TIMING OF POWER ON GNSS................................................................................................................ 49
FIGURE 45: TIMING OF POWER OFF GNSS .............................................................................................................. 49
FIGURE 46: CONNECTION FOR SOFTWARE UPGRADING AND DEBUGGING FOR GNSS .............................. 50