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Chapter 3. External Bus Interface and Memory Map
3-7
PRELIMINARY—SUBJECT TO CHANGE WITHOUT NOTICE
External Bus Interface
The complete MPC180E register map, including all execution units, is available to the host.
Although the host can access control registers and input and output buffers while an
instruction is executing, it cannot access the execution unit itself.
3.3.1.2 ID Register
Figure 3-3 shows the ID register. Note that the ID register contains a 32-bit value that
identifies the version of MPC180E. Its value at reset is 0x0045_1490 for ECC enabled or
0x0045_1491 for ECC disabled.
24–27
Destination
Destination bits. Only one execution unit on MPC180E can be active at a time through FIFO
accesses, so the host must program CSTAT to enable the appropriate execution unit. The
host must guarantee that all data related to a specific operation has been processed before
updating CSTAT, otherwise unpredictable results occur in MPC180E because the controller
acts on one execution unit at a time.
1000 DEU
1001 AFEU
1010 MDEU
1011 RNG
1100 PKEU
0xxx no active module
28–30 AUTO-
UNMASK
Auto-unmask bit. Enables or disables the auto-unmask function. This function is used to
unmask an interrupt from the currently active execution unit. It is to be used when a
execution unit sends a series of intermediate interrupts the host does not want to see. For
example, if the DEU is enabled and active, many interrupts may be generated for
intermediate results. The host, however, may only be interested in the final interrupt that
occurs when the DEU completes processing all of the data. To begin the operation, the host
masks off the interrupts from the DEU and then writes to the auto-unmask bit. Then, when
the DEU completes processing all the data, the controller unmasks the DEU interrupt and
allows the final DEU interrupt (signaling the completion of processing) to be sent to the host.
The host can then read CSTAT to determine that the DEU generated an interrupt and take
appropriate action.
for bits 28–30:
000 disabled
001 enabled
31
RST
Software reset. Performs the same function as asserting RESET on MPC180E. Setting this
bit resets the MPC180E within two MCLK cycles; the controller clears this bit.
0 —
1 chip reset
Table 3-3. CSTAT Field Descriptions
Bits
Name
Description
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