MPC555
/
MPC556
SYSTEM CONFIGURATION AND PROTECTION
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
6-25
6.13.2 SIU Interrupt Registers
The SIU interrupt controller contains the SIPEND, SIMASK, SIEL, and SIVEC regis-
ters.
6.13.2.1 SIPEND Register
Each of the 32 bits in the SIPEND register corresponds to an interrupt request. The
bits associated with internal exceptions indicate, if set, that an interrupt service is re-
quested (if not masked by the corresponding bit in the SIMASK register). Each bit re-
flects the status of the internal requestor device and is cleared when the appropriate
actions are initiated by the software in the device itself. Writing to these bits while they
are not set has no effect.
The bits associated with the IRQ pins have a different behavior depending on the sen-
sitivity defined for them in the SIEL register. When the IRQ is defined as a “level” in-
terrupt the corresponding bit behaves similar to the bits associated with internal
interrupt sources. When the IRQ is defined as an “edge” interrupt and if the corre-
sponding bit is set, it indicates that a falling edge was detected on the line and the bit
can be reset by software by writing a 1 to it.
6.13.2.2 SIU Interrupt Mask Register (SIMASK)
The SIMASK is a 32-bit read/write register. Each bit corresponds to an interrupt re-
quest bit in the SIPEND register. Setting a bit in this register allows the interrupt re-
quest to reach the RCPU. SIMASK is updated by the software and cleared upon reset.
It is the responsibility of the software to determine which of the interrupt sources are
enabled at a given time.
SIPEND
— SIU Interrupt Pending Register
0x2F C010
MSB
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
IRQ0
LVL0
IRQ1
LVL1
IRQ2
LVL2
IRQ3
LVL3
IRQ4
LVL4
IRQ5
LVL5
IRQ6
LVL6
IRQ7
LVL7
RESET:
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
LSB
31
RESERVED
RESET:
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
SIMASK
— SIU Interrupt Mask Register
0x2F C014
MSB
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
IRM0*
LVM0
IRM1
LVM1
IRM2
LVM2
IRM3
LVM3
IRM4
LVM4
IRM5
LVM5
IRM6
LVM6
IRM7
LVM7
RESET:
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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