SI4438 Wireless Module
User Manual of E30 Series Modules
Copyright ©2012–2017, Chengdu Ebyte Electronic Technology Co., Ltd.
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3.2.2 Pin Definition
Pin No.
Pin item
Pin direction
Pin application
1
M0
Input
（weak pull-up）
Work with M1 & decide the four operating modes.
(Floating is not allowed, can be ground)
2
M1
Input
（weak pull-up）
Work with M0 & decide the four operating modes.
(Floating is not allowed, can be ground)
3
RXD
Input
TTL UART inputs, connects to external (MCU, PC) TXD output pin. Can be
configured as open-drain or pull-up input.
4
TXD
Output
TTL UART outputs, connects to external RXD (MCU, PC) input pin. Can be
configured as open-drain or push-pull output
5
AUX
Output
To indicate module’s working status & wakes up the external MCU. During the
procedure of self-check initialization, the pin outputs low level. Can be configured
as open-drain output or push-pull output.
(Floating is allowed)
6
VCC
Input
Power supply 2.3V~5.5V DC
7
GND
Input
Ground
8
ANT
Output
Antenna interface（ high frequency signal output）
9
GND
Output
Reference places of high frequency signal output
10
GND
Input
Ground
11
GND
Input
Ground
4. Recommended Circuit Diagram
No.
Description（STM8L MCU）
1
The UART module is TTL level. Please connect to MCU of TTL level.
2
For some MCU working at 5VDC, it may need to add 4-10K pull-up resistor for the TXD & AUX pin.
