Figure 1. Sectional view of PCB assembly highlighting all laser mouse components

(laser mouse sensor, clip, lens, VCSEL, PCB, and base plate)

The CC2500 is a single chip 2.4GHz transceiver designed

for very low power wireless applications. The circuit

is intended for the ISM and SRD frequency band at

2400MHz-2483.5MHz. The RF transceiver is integrated

with a highly configurable baseband modem which

has a configurable data rate up to 500kbps. CC2500

provides extensive hardware support for packet han-

dling, data buffering, burst transmissions, clear channel

assessment, link quality indication and wake on radio.

The main operating parameters and the 64-byte trans-

mit/receive FIFOs of CC2500 can be controlled via an

SPI interface.

The Holtek HT82K68E is an 8-bit high performance

peripheral interface OTP microcontroller, designed for

multiple I/O product and HT68K96E are the 8-bit high

performance RISC-like microcontroller designed for USB

product applications. A HALT feature is included in both

HT82K68E and HT68K96E to reduce power consump-

tion.

This kit is connectable to a PC via the USB port. It is

based on the 2.4 GHz RF technology, the data gener-

ated from displacement detection/button status in the

laser mouse is encoded with a pre-defined serial type

protocol handled by firmware in the MCU. In the RF

stage, the encoded data is used for FSK modulation. The

captured data from the RF receiver stage is decoded

with a corresponding packet format used for mouse ap-

plications. The final data is sent to the host through the

USB interface.

SENSOR

VSCEL PCB

BASE PLATE

LENS

SURFACE

VSCEL

CLIP

PCB