CPM Interrupt Controller
MPC885 PowerQUICC Family Reference Manual, Rev. 2
Freescale Semiconductor
35-5
Figure 35-2. Interrupt Request Masking
The following procedure prevents possible interrupt errors when modifying mask registers, such as the
CIMR, SCCM, SMCM, or any other CPM interrupt mask:
1. Clear MSR[EE]. (Disable external interrupts to the core.)
2. Modify the mask register.
3. Set MSR[EE]. (Enable external interrupts to the core.)
This mask modification procedure ensures that an already pending interrupt is not masked before being
serviced. Masking a pending interrupt causes the interrupt error vector (see
Table 35-2
) to be issued if no
other valid CPM interrupts are pending. (The error vector cannot be masked.)
35.4
Generating and Calculating Interrupt Vectors
Unmasked CPM interrupts are presented to the core in order of priority. The core responds to an interrupt
request by setting CIVR[IACK]. The CPIC passes the five low-order bits of the vector corresponding to
the highest priority, unmasked, pending CPM interrupt in CIVR[VN]. These encodings are shown in
Table 35-2
.
Table 35-2. Interrupt Vector Encodings
Interrupt
Number
Source Description
CIVR[0–4]
Interrupt
Number
Source Description
CIVR[0–4]
0x1F
Parallel I/O–PC15
11111
0x0F
Parallel I/O—PC11
01111
0x1E
USB
11110
0x0E
Parallel I/O—PC10
01110
0x1D
SCC2
11101
0x0D
Reserved
01101
0x1C
SCC3
11100
0x0C
Timer 3
01100
0x1B
SCC4
11011
0x0B
Parallel I/O—PC9
01011
BRK
–
BSY
TX
RX
BRK
–
BSY
TX
RX
• • •
SMCx Interrupt to CPIC
• • •
3
4
5
6
7
3
4
5
6
7
SMCMx
SMCEx
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