NB-IoT Module Series
BC65 Hardware Design
BC65_Hardware_Design 27 / 55
The reset timing is illustrated in the following figure.
VBAT
> 900 ms
Resetting
Module Status
Running
RESET_N
Restart
≥ 1 s
VDD_EXT
Figure 13: Reset Timing
3.8. UART Interfaces
The module provides three UART interfaces: one main UART, one debug UART and one auxiliary UART*.
The module is designed as DCE (Data Communication Equipment), following the traditional DCE-DTE
(Data Terminal Equipment) connection.
Table 12: Pin Definition of UART Interfaces
Interface
Pin Name
Pin No.
Description
Comment
Main UART
MAIN_RXD
18
Main UART receive
1.8 V power
domain
MAIN_TXD
17
Main UART transmit
Debug UART
DBG_RXD
38
Debug UART receive
DBG_TXD
39
Debug UART transmit
Auxiliary UART*
AUX_RXD
28
Auxiliary UART receive
AUX_TXD
29
Auxiliary UART transmit
Ring Indication
RI
20
Ring indication signal (when there is
an SMS or URC output, the module
will inform DTE with RI pin)
