WCH CH9325

The CH9325 is a USB interface chip, which converts data received via UART to USB and vice versa. The chip presents a HID (Human Interface Device) USB profile, in an effort to not require USB driver installation: this is typically handled by the OS kernel. An example of the profile, in Linux 'lsusb' output format, is here.

The chip runs off of a 12MHz oscillator.

Pin layout

	1-	O	-16
UART TX	2-		-15	USB +5V
UART RX	3-		-14
	4-		-13
	5-		-12
USB D+	6-		-11
USB D-	7-		-10	OSC+
GND	8-		-9	OSC-

Protocol

The chip encodes what it receives on the UART RX pin into HID packets of 8 bytes.