LTE Standard Module Series
EC21_Series_Hardware_Design
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3.19. RI
AT+QCFG="risignaltype","physical" can be used to configure RI behavior. No matter on which port a
URC is presented, the URC will trigger the behaviors of RI pin. See document [3] for details.
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.
In addition, RI behavior can be configured flexibly. The default behaviors of the RI is shown as below.
Table 23: Behaviors of RI
State Response
Idle RI keeps at high level
URC RI outputs 120 ms low pulse when a new URC returns
The RI behavior can be changed by AT+QCFG="urc/ri/ring". See document [2] for details.
3.20. USB_BOOT Interface
EC21 series provides a USB_BOOT pin. Customers 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
Pin Name Pin No. I/O Description Comment
USB_BOOT 115 DI
Force the module to
enter emergency
download mode
1.8 V power domain.
Cannot be pulled up before startup.
Active high.
It is recommended to reserve test point.
NOTE
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