User's Manual

2. Reminds to hardware design

2.1 Application

The module is designed with an UART interface, it support TCP/IP protocol, users

can use the UART port to transfer data via WiFi connection to other internet devices.

Fig. 2-1 To use external MCU

2.2 GPIO Descriptions

The KM22 module designed with 4 GPIO port , the fastest interrupt request time is about 1ms。

Each GPIO port can be individually configured as an input or output via software. To stabilize the

interface communication, you can add a pull-push circuit as below:

Fig. 2- 2 Reference design of GPIO pins

Notes: The supply voltage is 3.3V for this module. The default voltage setting of GPIO is also 3.3V.

Should other voltage system be applied, a voltage converter must be used.

Remarks: the GPIO3 was default assigned for LED display, if this port must be used for other