11 CACHE CONTROLLER (CCU)
S1C33L26 TECHNICAL MANUAL
Seiko Epson Corporation
11-7
When WBEN is set to 1 (default), the write buffer is enabled. When the write buffer is enabled, writing
data to the external memory is performed in two steps, first the data is written to the write buffer and
then the external memory is updated.
When WBEN is set to 0, the write buffer is disabled. In this case the CPU is placed into wait status until
the data writing to the external memory has completed.
D[7:3]
Reserved (Do not set D3 to 1.)
D2
SBRK: Software Break Enable Bit
Enables the software PC break function during debugging.
1 (R/W): Enabled (default)
0 (R/W): Disabled
Note: When SBRK is set to 0, a software PC break point cannot be set in the a target area for cach-
ing.
D1
IC: Instruction Cache Enable Bit
Enables the instruction cache.
1 (R/W): Enabled
0 (R/W): Disable (default)
By setting IC to 1, addresses 0x1f800 to 0x1fbff (1KB) in Area 0 are set for use as the instruction cache,
after which the cache is used for fetching instructions from the specified area.
Setting IC to 0 flushes the instruction cache and clears all cache data. Note that the cache is flushed
several cycles after writing 0 to IC. Before resuming caching operation, check ICS/CCU_STAT register
to ensure that flushing is completed.
D0
DC: Data Cache Enable Bit
Enables the data cache.
1 (R/W): Enabled
0 (R/W): Disable (default)
By setting DC to 1, addresses 0x1fc00 to 0x1ffff (1KB) in Area 0 are set for use as the data cache, after
which the cache is used for reading data from the specified area. Data is written in the write through
mode.
Setting DC to 0 flushes the data cache and clears all cache data. Note that the cache is flushed several
cycles after writing 0 to DC. Before resuming caching operation, check DCS/CCU_STAT register to
ensure that flushing is completed.
Note: Be sure to disable the instruction and data caches before executing the halt or slp instruction.
Cacheable Area Select Register (CCU_AREA)
Register name Address
Bit
Name
Function
Setting
Init. R/W
Remarks
Cacheable Area
Select Register
(CCU_AREA)
0x302304
(32 bits)
D31–7 –
reserved
–
–
–
0 when being read.
D6–4 ARIC[2:0]
Instruction cache area select
ARIC[2:0]
Area
0x0 R/W
0x7
0x6
0x5
0x4
0x3
0x2
0x1
0x0
Area 22
Area 21
Area 20
Area 19
Area 18
Area 17
Areas 15 & 16
Area 14
D3
–
reserved
–
–
–
0 when being read.
D2–0 ARDC[2:0] Data cache area select
ARDC[2:0]
Area
0x0 R/W
0x7
0x6
0x5
0x4
0x3
0x2
0x1
0x0
Area 22
Area 21
Area 20
Area 19
Area 18
Area 17
Areas 15 & 16
Area 14
D[31:7] Reserved