SIM Tech SIMCom SIM900-DS Hardware Design page 14

GPIO1 67
Serial port
RXD 10
TXD 9
RTS 8
CTS 7
DCD 5
RI 4
DTR 3
Debug interface
DBG_TXD 27
DBG_RXD 28
SIM1 interface
SIM1_VDD 30
SIM1_DATA 31
SIM1_CLK 32
SIM1_RST 33
SIM1_PRESENCE 34
SIM2 interface
SIM2_VDD 43
SIM2_DATA 35
SIM2_CLK 36
SIM2_RST 40
SIM2_PRESENCE 44
ADC
ADC 25
External reset
NRESET 16
PCM interface
PCM_SYNC 48
PCM_OUT 47
PCM_IN 41
PCM_CLK 42
RF interface
RF_ANT 60
Not connect
NC 6
SIM900-DS_Hardware Design_V1.00
GPIO1
I Receive data
O Transmit data
I Request to send
O Clear to send
O Data carrier detect
O Ring indicator
I Data terminal ready
O For debugging
firmware
I
Voltage supply for SIM card.
O
Support 1.8V or 3V SIM card
I/O SIM1 data input/output
O SIM1 clock
O SIM1 reset
I SIM1 card detection
Voltage supply for SIM card.
O
Support 1.8V or 3V SIM card
I/O SIM2 data input/output
O SIM2 clock
O SIM2 reset
I SIM2 card detection
I Input voltage range: 0V ~ 2.8V
I Reset input(Active low)
O PCM sync
O PCM data output
I PCM data input
O PCM CLK
I/O Radio antenna connection
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14
Smart Machine Smart Decision
If these pins are unused,
keep open.
and upgrading If these pins are unused,
keep open.
All signals of SIM
interface should be
protected against ESD
with a TVS diode array.
If it is unused, keep open.
All signals of SIM
interface should be
protected against ESD
with a TVS diode array.
If it is unused, keep open.
If it is unused, keep open.
Recommend connecting
a 100nF capacitor.
If these pins are unused,
keep open.
Impendence
controlled to 50Ω.
This pin should be kept
open.
must be
2013-01-20