mpc823rg Freescale Semiconductor, Inc, mpc823rg Datasheet - Page 961

• Manufacturer Part Number: mpc823rg
• Description: Mpc823 Powerquicc Integrated Communications Processor For Portable Systems
• Manufacturer: Freescale Semiconductor, Inc

16.15.6.2 USB INTERRUPT HANDLER EXAMPLE. In this example, the USB bit in the
CIPR remains set as long as one or more unmasked event bits remain in the USBE register.
This is an example of a handler for an interrupt source with multiple events. Notice that the
USB bit in the CIPR does not need to be cleared by the handler, but the USB bit in the CISR
does.
1. Set the IACK bit in the CIVR.
2. Read the vector to access the interrupt handler.
3. Immediately read the USBE register into a temporary location.
4. Choose the events in the USBE that will be handled in this handler and clear them.
5. Handle the events in the USB RX or TX buffer descriptor tables.
6. Clear the USB bit in the CISR.
7. Execute the rfi instruction. If any unmasked bits (those not cleared by the software or
The USBE bits are cleared by writing ones.
set by the MPC823 during the execution of this handler) in the USBE remain at this
time, this interrupt source is pending again after the rfi instruction.
Freescale Semiconductor, Inc.
For More Information On This Product,
MPC823 REFERENCE MANUAL
Go to: www.freescale.com
Communication Processor Module
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