N720 OpenLinux
Hardware User Guide
Copyright © Neoway Technology Co., Ltd
66
3.8.5 USB_BOOT
Pin 48 is also the USB_BOOT pin in addition to WCT_LTE_RXD. It is the last method to handle issues
that result in startup or running failures.
Connect USB_BOOT to VDDIO_1P8 through a pull-up resistor transiently after the module is started,
and the module will enter forcible download mode.
Reserve this pin to facilitate software upgrade and debugging. Figure 3-63 shows the reference design
of this pin.
Figure 3-63 Reference design of USB_BOOT
10kΩ
DVDD_1P8
USB_BOOT
R1
10kΩ
R2
S1
ESD1
ESD2
Add an ESD component to protect USB_BOOT in circuit.