I2C Interface; I2C Design Guide - SIM Tech SIMCom SIM7100-PCIE Hardware Design

To comply with RS-232-C protocol, the RS-232-C level shifter chip should be used to connect SIM7100-PCIE
to the RS-232-C interface. In this connection, the TTL level and RS-232-C level are converted mutually.
SIMCom recommends that user uses the SP3238ECA chip with a full modem. For more information please
refers to the RS-232-C chip datasheet.
Note: SIM7100-PCIE supports the following baud rate: 300, 600, 1200, 2400, 4800, 9600, 19200, 38400,
57600, 115200, 230400, 460800, 921600, 3200000, 3686400, 4000000bps. Default baud rate is 115200bps.
3.8

I2C Interface

SIM7100-PCIE provides I2C interface compatible with I2C specification, version 2.1, with clock rate up to 400
kbps. Its operation voltage is 1.8V.
Note: Since the I2C is connected to the audio codec chip on board,the users should choose the I2C device
whose address is not the same with the audio codec.If the the audio codec chip is not mounted on board,users
could ignore this.

3.8.1 I2C Design Guide

The following figure shows the I2C bus reference design.
Note: SDA and SCL are pulled up to 1.8V via 10K resistors in module. So external pull up resistors are not
needed in application circuit. For more details about I2C AT commands please refer to document [1].
SIM7100-PCIE_Hardware_Design_V1.05
1V8
MODULE
100nF
TXD
RXD
RTS
CTS
DTR
RI
47K
47K
UART port
Figure 15: Reference circuit of level shift
SCL
SDA
GND
Module
Figure 16: I2C Reference Circuit
3V3
TXB0108RGYR
100nF
VCCA VCCB
OE
GND
TXD_3.3V
A1 B1
A2 B2 RXD_3.3V
B3
A3 RTS_3.3V
B4
A4 CTS_3.3V
A5 B5 DTR_3.3V
RI_3.3V
B6
A6
47K
A7 B7
47K
A8 B8
SCL
SDA
GND
Device
22
Smart Machine Smart Decision
2017-02-24