N11
Hardware User Guide
Copyright © Neoway Technology Co., Ltd
18
Figure 3-12
Recommended level shifting circuit 2
C1 220pF
UART_TXD
R1 10 k
Ω
R
2
4
7
k
Ω
R
3
4
.7
k
Ω
VDDIO_2P8
R4 22 k
Ω
C2 220pF
R
5
4
7
k
Ω
R
6
4
.7
k
Ω
Q1
Q2
MCU_RXD
VCC_IO
C1 220pF
UART_RXD
R1 10 k
Ω
R
2
1
0
k
Ω
R
3
4
.7
k
Ω
VDDIO_2P8
R4 4.7 k
Ω
C2 220pF
R
5
4
7
k
Ω
R
6
4
.7
k
Ω
Q1
Q2
MCU_TXD
Q1, Q2: MMBT3904 or MMBT2222. High-speed transistor is better.
MCU_TXD and MCU_RXD are respectively the TX and RX ports of the MCU while UART_TXD and
UART_RXD are respectively the TX and RX ports of the module.
VCC_IO indicates the voltage at the UART of the MCU while VDDIO_2P8 indicates the voltage at the
UART of the module.
