NB-IoT Module Series
BC66 Hardware Design
BC66_Hardware_Design 26 / 57
“*” means under development.
3.8.1. Main UART Port
The main UART port supports AT command communication, data transmission and firmware upgrade.
By default, the module is in auto-baud mode and it supports automatic baud rates not exceeding
115200bps. When powering on the module, the MCU has to send
AT
command consecutively to
synchronize baud rate with the module. When
OK
is returned, it indicates the baud rate has been
synchronized successfully. When the module is woken up from PSM or idle mode, the baud rate
synchronized during start-up will be used directly.
When the port is used for firmware upgrade, the baud rate is 921600bps by default.
The figure below shows the connection between DCE and DTE.
TXD
RXD
TXD
RXD
Module (DCE)
Serial port
Main port
GND
GND
DTE
Figure 14: Reference Design for Main UART Port
3.8.2. Debug UART Port
Through debug tools, the debug UART port can be used to output logs for firmware debugging. Its baud
rate is 115200bps by default. The following is a reference design of debug UART port.
NOTE
