N58 Hardware User Guide
Chapter 5 Application Interfaces
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45
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EN is the enable pin, and is triggered by an input level that is greater than VL-0.2 V. In the
preceding figure, EN is directly connected to VDD_1P8, and the level shifting chip is always
working.
If the UART interface baud rate is lower than or equal to 115200 bps, it is recommended to use
level shifting circuit 2 (see Figure 5-21) for UART interface TXD and RXD and is recommended
to use level shifting circuit 3 (see Figure 5-22) for UART interface CTS and RTS.
Figure 5-21 Recommended level shifting circuit 2
C1
C2
10pF
UART_RXD
10 k
Ω
100 k
Ω
10 k
Ω
VDD_1P8
10k
Ω
10pF
100 k
Ω
4.7 k
Ω
Q1
Q2
MCU_TXD
R4
R1
R6
R5
R2
R3
C1
C2
10pF
UART_TXD
4.7 k
Ω
R2
10 k
Ω
VDD_1P8
10k
Ω
10pF
100k
Ω
4.7 k
Ω
Q1
Q2
MCU_RXD
VCC_IO
R4
R1
R5
R6
R3
22 k
Ω
Related components:
Q1/Q2: MMBT3904 or MMBT2222. High-rate transistors are better.
MCU_TXD and MCU_RXD are the sending and receiving interfaces of the MCU, respectively. TXD
and RXD are the sending and receiving interfaces of the module, respectively. VCC_IO is the IO
voltage of the MCU, and VDD_1P8 is the IO voltage of the module.