Designing a Low-Cost USB Mouse with the Cypress Semiconductor ...

Designing a Low-Cost USB Mouse
Remote Wake-Up
Clear Cext
Compare Port 0 value
to stored Port 0 value
Check for mouse or a button press
Same
Y
If same, no mouse movement
N
Write RESUME bit
03h to USB Status and
Control reg.
If different, wake-up host
Loop for 10 ms
(remember to reset
WD timer)
Send resume signal for 10 ms
Clear RESUME bit
write 00h to USB Status
and Control reg
Set Cext to High Z
Return
Figure 17. Remote Wake-Up Interrupt
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