Power Management - Motorola M68HC08 Designer Reference Manual

Mouse Transmitter Firmware

5.2 Power Management

DRM055
22
Freescale Semiconductor, Inc.
A timer interrupt is set for every 104 µs which is the base time for the 4.8-kHz
data rate transmission. By configuring the timer to output compare mode, the
RF_Data output pin can be set, cleared, or toggled for every 104 µs. The timer
interrupt routine determines whether to set or clear the RF_Data pin at the next
interrupt time. It also determines what the current RF_Off pin status should be.
Power management plays a very important role in the wireless optical mouse
solution.
XY MOVEMENT
SENSOR AND ZLED TURNED ON
FOR EVERY 200 MILLISECONDS
(EVERY 500 MILLISECONDS IF IN
SLEEP FOR MORE THAN 10 MINUTES)
SLEEP
Figure 5-2. Power Management
Figure 5-2 shows the power management flow. There are three defined
stages:
• Power saving
• High current
• Sleep
After power up, the mouse is put in the power saving stage. In this stage, the
sensor is only turned on every 20 milliseconds to see if any XY movement
happened. The Z movement and buttons are sensed every millisecond.
If no activity happens for 90 seconds, it enters sleep stage. In this stage, the
QY4 is put in stop mode and will wake up every 200 milliseconds to monitor any
Mouse Transmitter Firmware
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SENSOR FULLY TURNED ON
ZLED TURNED ON
FOR EVERY 1 MILLISECOND
HIGH CURRENT
XY MOVEMENT
Z MOVEMENT
OR BUTTON
XYZ NO MOVEMENT
AND
NO BUTTON FOR 90 SECONDS
High Data Rate Wireless USB Optical Mouse Solution
XY NO MOVEMENT
FOR 5 SECONDS
SENSOR TURNED ON EVERY
20 MILLISECONDS, ZLED TURNED
ON FOR EVERY 1 MILLISECOND
POWER SAVING
(STARTUP)
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