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N720 OpenLinux
Hardware User Guide
Copyright © Neoway Technology Co., Ltd
29
Figure 3-18 Recommended level shifting circuit 1
MCU_RXD
MCU_TXD
UART_TXD
VDD_1P8
VCC_IO
4.7kΩ
10kΩ
Q1
R2
R1
VDD_1P8
VCC_IO
4.7kΩ
10kΩ
Q2
R3
R4
MCU_RXD
If the low level at MCU_UART (V
IL
) is lower than 200mV, adopt recommended level shifting circuit 2.
Otherwise, low level at UART might be higher than required, resulting in failure to identify signals.