N11
Hardware User Guide
Copyright © Neoway Technology Co., Ltd
15
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
Pin
Signal
I/O
Function Description
Remarks
12
UART_TXD
DO
UART data transmit
11
UART_RXD
DI
UART data receive
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
UART_RXD
UART_TXD
MCU_TXD
MCU_RXD
GND
GND
N11
Client
Schematic Design Guidelines
⚫
Note the match of signals.
