Freescale Semiconductor PowerQUICC MPC885 Reference Manual page 299

System Interface Unit
Write any other value to the key register
Power-on reset
Open Locked
Write 0x55CC_AA33 to the key register
Figure 10-6. Register Lock Mechanism
10.5 System Configuration
The SIU module configuration register (SIUMCR) is used for configuring external bus arbitration logic,
external master support, and pin multiplexing. See Section 10.4.2, "SIU Module Configuration Register
(SIUMCR)."
10.5.1 Interrupt Structure
The SIU receives interrupts from internal sources, like the PIT, communications processor module (CPM),
and the external IRQ pins. Figure 10-7 shows the MPC885 interrupt structure.
MPC885 PowerQUICC Family Reference Manual, Rev. 2
Freescale Semiconductor 10-11