Dual-Port TPU3 RAM (DPTRAM)
MPC561/MPC563 Reference Manual, Rev. 1.2
20-8
Freescale Semiconductor
When the DPTRAM array is being used by one or two of the TPU3 units, all accesses via the IMB3 are
disabled. The control registers have no effect on the RAM array.
The contents of the RAM are validated using a multiple input signature calculator (MISC). MISC reads of
the RAM are performed only when the MPC561/MPC563 is in emulation mode and the MISC is enabled
(MISEN = 1 in the DPTMCR).
Refer to
Section 19.3.6, “Emulation Support
” for more information in TPU3 and DPTRAM operation in
emulation mode.
20.5
Multiple Input Signature Calculator (MISC)
The integrity of the DPTRAM data is ensured through the use of a MISC. The DPTRAM data is read in
reverse address order and a unique 32-bit signature is generated based on the output of these reads. MISC
reads are performed when one of the TPU3 modules does not request back-to-back accesses to the
DPTRAM provided that the MISEN bit in the DPTMCR is set.
The MISC generates the DPTRAM signature based on the following polynomial:
Eqn. 20-1
After the entire DPTRAM has been read and a signature has been calculated, the MISC sets the MISF bit
in the DPTMCR. The host should poll this bit and enter a handling routine when the bit is found to be set.
The signature should then be read from the MISRH and MISRL registers and the host determines if it
matches the predetermined signature.
The MISRH and MISRL registers are updated each time the MISC completes reading the entire DPTRAM
regardless of whether or not the previous signature has been read or not. This ensures that the host reads
the most recently generated signature.
The MISC can be disabled by clearing the MISEN bit in the DPTMCR.
NOTE
The reset state of the DPTMCR[MISEN] is disabled.
G x
( )
1
x
x
2
x
22
x
31
+
+
+
+
=
Summary of Contents for MPC561
Page 84: ...MPC561 MPC563 Reference Manual Rev 1 2 lxxxiv Freescale Semiconductor...
Page 144: ...Signal Descriptions MPC561 MPC563 Reference Manual Rev 1 2 2 46 Freescale Semiconductor...
Page 206: ...Central Processing Unit MPC561 MPC563 Reference Manual Rev 1 2 3 62 Freescale Semiconductor...
Page 302: ...Reset MPC561 MPC563 Reference Manual Rev 1 2 7 14 Freescale Semiconductor...
Page 854: ...Time Processor Unit 3 MPC561 MPC563 Reference Manual Rev 1 2 19 24 Freescale Semiconductor...
Page 968: ...Development Support MPC561 MPC563 Reference Manual Rev 1 2 23 54 Freescale Semiconductor...
Page 1144: ...Internal Memory Map MPC561 MPC563 Reference Manual Rev 1 2 B 34 Freescale Semiconductor...
Page 1212: ...TPU3 ROM Functions MPC561 MPC563 Reference Manual Rev 1 2 D 60 Freescale Semiconductor...
Page 1216: ...Memory Access Timing MPC561 MPC563 Reference Manual Rev 1 2 E 4 Freescale Semiconductor...