Designing a Low-Cost USB Mouse with the Cypress Semiconductor ...
Designing a Low-Cost USB Mouse with the Cypress Semiconductor ...
Designing a Low-Cost USB Mouse with the Cypress Semiconductor ...
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<strong>Designing</strong> a <strong>Low</strong>-<strong>Cost</strong> <strong>USB</strong> <strong>Mouse</strong><br />
1 ms<br />
• Clear watchdog<br />
timer<br />
Y<br />
Remote<br />
Wakeup<br />
process?<br />
• Increment 10 msec wakeup<br />
counter<br />
N<br />
<strong>USB</strong> bus<br />
activity<br />
N<br />
Y<br />
• Load software counter<br />
• Clear bus activity bit<br />
• Decrement software<br />
counter<br />
N<br />
software<br />
counter = 0<br />
Y<br />
• Enable global interrupts except Cext<br />
and 128 µs<br />
Remote<br />
Wakeup<br />
Enabled?<br />
N<br />
Y<br />
return<br />
•Clear Cext<br />
• Set Cext to High-Z<br />
• Enable Cext interrupts<br />
• Load software counter<br />
• Suspend µC and wait for interrupts<br />
Figure 16. One msec Interrupt Service Routine<br />
10
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