LTE Standard Module Series
EG915U_Series_Hardware_Design 48 / 81
Figure 23: Reference Circuit with Translator Chip
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Another example with transistor translation circuit is shown as follows. For the design of circuits in dotted
lines, please refer to that of the circuits in solid lines, but please pay attention to the direction of
connection.
MCU/ARM
TXD
RXD
VDD_EXT
10K
VCC_MCU
4.7K
10K
VDD_EXT
MAIN_TXD
MAIN_RXD
MAIN_RTS
MAIN_CTS
MAIN_DTR
MAIN_RI
RTS
CTS
GND
GPIO
MAIN_DCD
Module
GPIO
EINT
VDD_EXT
4.7K
GND
1 nF
1 nF
Figure 24: Reference Circuit with Transistor Circuit
4.7. ADC Interface
The module provides two analog-to-digital converter (ADC) interfaces. You can use
AT+QADC=0
to read
the voltage value on ADC0 pin,
AT+QADC=1
to read the voltage value on ADC1, See
document [2]
for
more details.
In order to improve the accuracy of ADC, the trace of ADC should be surrounded by ground.
1. Transistor circuit solution is not suitable for applications with baud rates exceeding 460 kbps.
2. Please note that the module CTS is connected to the host CTS, and the module RTS is connected
to the host RTS.
NOTE
