HC 21 Embed WiFi to Serial Port UART Wireless Module for Raspberry Pi Arduino

NRESET

Reset , active low

Link

Wireless transmission indication (LED Connect this pin )

nCTS

CTS signal in the automatic mode, as the end of the CTS signal can be directly connected to the end of the RTS signal

GPIO

According to user settings can be used as general-purpose input and output pins

nRTS

In automatic mode, as the end of the RTS signal can be directly connected with the peer CTS signals.

nREADY

In command mode, indicating the state of Wi-Fi connection of the module . Low indicates connected , high indicates not connected

VDD

3.3V power input pin (LED Connect this pin )

RXD

Pin serial data receiver

TXD

Pin serial data transmission

GND

ground