MPC555
/
MPC556
U-BUS TO IMB3 BUS INTERFACE (UIMB)
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
12-8
12.5.2 Test control register (UTSTCREG)
The UTSTCREG register is used for factory testing only.
12.5.3 Pending Interrupt Request Register (UIPEND)
The UIPEND register is a read-only status register which reflects the state of the 32
interrupt levels. The state of the IRQ0 is shown in bit 0, the state of IRQ1 is shown in
bit 1 and so on. This register is accessible only in supervisor mode.
Table 12-6 UMCR Bit Descriptions
Bit(s)
Name
Description
0
STOP
Stop enable.
0 = Enable system clock for IMB bus
1 = Disable IMB system clock
To avoid complications at restart and data corruption, system software must stop each slave on
the IMB before setting the STOP bit. Software must also ensure that all IMB interrupts have been
serviced before setting this bit.
1:2
IRQMUX
Interrupt request multiplexing. These bits control the multiplexing of the 32 possible interrupt re-
quests onto the eight IMB interrupt request lines.
00 = Disables the multiplexing scheme on the interrupt controller within this interface. What this
means is that the IMB IRQ [0:7] signals are non-multiplexed, only providing 8 (0-7) interrupt
request lines to the interrupt controller
01 = Enables the IMB IRQ control logic to perform a 2-to-1 multiplexing to allow transferring of
16 (0-15) interrupt sources
10 = Enables the IMB IRQ control logic to perform a 3-to-1 multiplexing to allow transferring of
24 (0-23) interrupt sources
11 = Enables the IMB IRQ control logic to perform a 4-to-1 multiplexing to allow transferring of
32 (0-31) interrupt sources
3
HSPEED
Half speed. The HSPEED bit controls the frequency at which the IMB3 runs with respect to the
U-bus. This is a modify-once bit. Software can write the reset value of this bit any number of
times. However, once logic 0 is written to this location, any attempt to rewrite this bit to a logic 1
will have no effect.
0 = IMB frequency is the same as that of the U-bus
1 = IMB frequency is one half that of the U-bus
4:31
—
Reserved
UIPEND
— Pending Interrupt Request Register
0x30 7FA0
MSB
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
LVL0
LVL1
LVL2
LVL3
LVL4
LVL5
LVL6
LVL7
LVL8
LVL9
LVL0
LVL11 LVL12 LVL13 LVL14 LVL15
HRESET:
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
LVL16
IRQ17 LVL18 LVL19 LVL20 LVL21 LVL22 LVL23 LVL24 LVL25 LVL26 LVL27 LVL28 LVL29 LVL30 LVL31
HRESET:
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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