LTE Standard Module Series
EG25-GL_Hardware_Design 59 / 96
Table 23: Behaviors of MAIN_RI
A URC can be outputted from UART port, USB AT port and USB modem port through configuration via
AT+QURCCFG
. The default port is USB AT port. See
document [2]
for details.
4.10 USB_BOOT
The module provides a USB_BOOT pin. You can pull up USB_BOOT to 1.8 V before VDD_EXT is
powered up, and the module will enter emergency download mode when it is powered on. In this mode,
the module supports firmware upgrade over USB interface.
Table 24: Pin Definition of USB_BOOT Interface
The following figures show the reference circuit of USB_BOOT interface and timing sequence of entering
emergency download mode.
State
Response
Idle
MAIN_RI keeps at high level
URC
MAIN_RI outputs 120 ms low pulse when a new URC returns
Pin Name
Pin No.
I/O
Description
Comment
USB_BOOT
115
DI
Force the module into
emergency download mode
1.8 V power domain.
Cannot be pulled up before startup.
It is recommended to reserve test point.
NOTE
