Use a common NPN transistor, e.g. MMBT3904; or a digital NPN transistor embedded with a serial
resistor, e.g. DTC123. If a digital transistor is used, delete R1 and R2.
⚫ Level abnormalities at interfaces connected to the external MCU, especially the UART port, might
affect the power-on procedure of the module. For example, when a module is turned on, the IO ports
of the MCU are still in output status because they have not been initialized completely. The module
might fails to start if the UTXD signal (output pin) is forced to pull up or down.
⚫ The better way to rescue the module from abnormal condition is to apply a power OFF-ON
procedure, rather than using the ON/OFF control signal. In fact ON/OFF signal is software-
dependent.
3.2 UART
Table 3-2 UART
The UART of N11 works at 2.8 V CMOS logic level. The voltages for input high level should not
exceed 3.1 V. The factory setting of UART is automatic adaption. UART supports baud rates of 9600,
14400, 19200, 38400, 57600, 115200 bit/s, and the default rate is 115200 bit/s.
Figure 3-9 shows the signal connection between the module (DCE) and the terminal (DTE).
Figure 3-9 Signal connection between DCE and DTE
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