User Manual

KwikBlue4-1
Bluetooth® Class 1 BC04 Module
Manual
June 21, 2005 Copyright © 2004-2005 Socket Communications, Inc. Page 12
Document#: CONFIDENTIAL Revision 0.1
simultaneously
3.5.4 Limitations
1) Power Specific Limitations: today, the host controller of USB capable machines resides inside
a chip known as PIIX4. Because of the design, the USB host controller will not receive power
while the system is in S3 or S4. This means that a USB wakeup can only occur when the system
is in S1 or S2.
Another issue with the USB host controller is that, while a device is attached, it continually
snoops memory to see if there is any work that needs to be done. The frequency that it checks
memory is 1ms. This prevents the processor from dropping into a low power state known as C3.
Because the notebook processor is not able to enter the C3 state, SIGNIFICANT power loss will
occur. This is a real issue for business users – as a typical business user will spend almost 90% of
their time in the C3 state.
2) Other Limitations
: data corruption may occur across isochronous endpoints. Endpoints one and
two may suffer from data corruption. USB provides 16-CRC on all data transfers. The USB has a
bit error rate of 10
–13 .