CALRAM Operation
MPC561/MPC563 Reference Manual, Rev. 1.2
22-14
Freescale Semiconductor
Table 22-3. CRAMMCR Bit Descriptions
Bits
Name
Description
0
LCK
Write protection — This bit is designed to lock out writes to the CRAMMCR. While LCK = 0 the
register can be written repeatedly without restriction.
If LCK = 1, the register does not accept writes (i.e., the value of the register remains unchanged,
but the cycle terminates normally.)
In normal mode, this bit can only be set once and can only be cleared by reset.
0 writes to the CRAMMCR are unrestricted
1 writes to the CRAMMCR are ignored
In freeze mode, only the LCK bit may be written to zero if it was previously set.
1
DIS
Array disable — When set, this bit disables the CALRAM array.
In this mode, all reads and writes to the CALRAM array are ignored and a bus error is generated.
The CALRAM responds to register access while DIS = 1.
This is a low power mode for the module, since all internal functions will be disabled.
The module can be re-enabled by writing the DIS bit back to a zero. Reset will also re-enable the
module.
0 CALRAM module array access is enabled
1 CALRAM module array access is disabled
2
2CY
Two cycle mode — When set, this bit puts the CALRAM into a two cycle access mode operation
for CALRAM register accesses as well as array accesses.
This mode provides power savings by using the first cycle to decode any L-bus access for an
address match to where the array resides.
0 CALRAM module in one-cycle operation
1 CALRAM module in two-cycle operation
3:19
—
Reserved
20
R0
Read-only/read-write privilege — If the data relocate (DR) bit is set in Machine Status Register
(MSR in RCPU) and R0 is also set, then write accesses are terminated with an error. If DR bit is
0, both reads and writes to the array block is allowed regardless of the value programmed in R0.
This bit controls the highest 8-Kbyte block (lowest address) of CALRAM in the associated array.
Likewise, R1, R2, and R3 control three other 8-Kbyte blocks in the same manner. See
for control bit address ranges.
R0 = 0 and DR = 0 readable and writable (array 8-Kbyte block)
R0 = 0 and DR = 1 readable and writable (array 8-Kbyte block)
R0 = 1and DR = 0 readable and writable (array 8-Kbyte block)
R0 = 1 and DR = 1 read only (array 8-Kbyte block)
21
D0
Data-only/data-instruction privilege (Data type assignment) — If the data relocate (DR) bit is set
in Machine Status Register (MSR) and D0 is also set, then any access attempting to fetch an
instruction from the array block generates an error. If DR bit is 0, both data read and instruction
fetch from the array block is allowed, regardless of the value programmed in D0.
This bit controls the highest 8-Kbyte block (lowest address) of CALRAM in the associated array.
Likewise, D1, D2, and D3 control three other 8-Kbyte blocks in the same manner. See
for control bit address ranges.
D0 = 0 and DR = 0 data and/or Instruction (array 8-Kbyte block)
D0 = 0 and DR = 1 data and/or Instruction (array 8-Kbyte block)
D0 = 1 and DR = 0 data and/or Instruction (array 8-Kbyte block)
D0 = 1 and DR = 1 data only (array 8-Kbyte block)
Summary of Contents for MPC561
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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...
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Page 1144: ...Internal Memory Map MPC561 MPC563 Reference Manual Rev 1 2 B 34 Freescale Semiconductor...
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Page 1216: ...Memory Access Timing MPC561 MPC563 Reference Manual Rev 1 2 E 4 Freescale Semiconductor...