Jinan USR IOT Technology WIFI232-A, User Manual

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USR-WIFI232-A/B/C User Manual http://www.usriot.com
Jinan USR IOT Technology Limited Page 25 of 93 tec@usr.cn
3.5.3 UART Interface
UART interface is the serial data transmition interface mainly used for USR-WIFI232-A/B/C
modules.
User can add RS-232 chipset on user board and convert the signal to RS-232 voltage to
communicate with outside equipment or sensors. USR-WIFI232-A/B/C modules UART interface
include 4 general signals: TXD/RXD/RTS/CTS. The hardware reference design with RS-232
chipset as following:
Figure 21
Figure Figure Figure Figure 10 10 10 10 UART UART UART UART Interface Interface Interface Interface Reference Reference Reference Reference Design Design Design Design
Notes: Notes: Notes: Notes: TXD pin is also hardware configuration pin internal module. So this pin MUST pull-down
during module power up. USR-WIFI232-A/B/C modules provide internal pull-down resister, user
can’t add pull-up/pull-down resister on user board, which may cause module can’t work.
3.5.4 Power Interface
USR-WIFI232-A/B/C module support 3.3V power supply. The peak current shall about
350mA and normal WiFi working current shall about 200mA. The power save (WiFi OFF) mode
will about 100mA
Decoupling at power pin suggested, At least one 100uF and one 10uF capacitor required at user
board and put near module power input pin will increase the reliability and performance.
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