MPC555
/
MPC556
DUAL-PORT TPU RAM (DPTRAM)
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
18-4
18.3.2 DPTRAM Test Register
RAMTST —
Test Register
0x30 0002
RAMTST is used only during factory testing of the MCU.
DPTMCR —
DPT Module Configuration Register
0x30 0000
MSB
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
LSB
15
STOP
NOT USED
MISF
MIS-
EN
RASP
Reserved
RESET:
0
0
0
1
0
0
0
0
0
0
0
0
Table 18-2 DPTMCR Bit Descriptions
Bit(s)
Name
Description
0
STOP
Low power stop (sleep) mode
0 = DPTRAM clocks running
1 = DPTRAM clocks shut down
Only the STOP bit in the DPTMCR may be accessed while the STOP bit is asserted. Accesses
to other DPTRAM registers may result in unpredictable behavior. Note also that the STOP bit
should be set and cleared independently of the other control bits in this register to guarantee
proper operation. Changing the state of other bits while changing the state of the STOP bit may
result in unpredictable behavior.
Refer to
for more information.
1:4
—
Reserved
5
MISF
Multiple input signature flag. MISF is readable at any time. This flag bit should be polled by the
host to determine if the MISC has completed reading the RAM. If MISF is set, the host should
read the MISRH and MISRL registers to obtain the RAM signature.
0 = First signature not ready
1 = MISC has read entire RAM. Signature is latched in MISRH and MISRL and is ready to be
read.
6
MISEN
Multiple input signature enable. MISEN is readable and writable at any time. The MISC will only
operate when this bit is set and the MPC555
/ MPC556 is in TPU3 emulation mode. When en-
abled, the MISC will continuously cycle through the RAM addresses, reading each and adding
the contents to the MISR. In order to save power, the MISC can be disabled by clearing the MIS-
EN bit.
0 = MISC disabled
1 = MISC enabled
7
RASP
Ram area supervisor/user program/data. The RAM array may be placed in supervisor or unre-
stricted Space. When placed in supervisor space, (RASP = 1), only a supervisor may access the
array. If a supervisor program is accessing the array, normal read/write operation will occur. If a
user program is attempting to access the array, the access will be ignored and the address may
be decoded externally.
0 = Both supervisor and user access to RAM allowed
1 = Supervisor access only to RAM allowed
8:15
—
Reserved
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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