USR-K2 Hardware Manual
Jinan USR IOT Technology Limited
7 / 9
Figure 5 Power interface
2.3. UART Interface
UART is serial data interface that can connect the RS-232 chip and transfer to the RS-232 level. UART
interface includes TXD/RXD.Taking the RS-232 level as a reference circuit diagram as follow:
Figure 6 RS232 level UART interface
When communicating to MCU with 3.3V, just connecting TXD of module to RXD of MCU and RXD of module
to TXD of MCU. When communicating to MCU with 5V, switching circuit is necessary.
Switching circuit diagram as follow:
