11 CACHE CONTROLLER (CCU)
S1C33L26 TECHNICAL MANUAL
Seiko Epson Corporation
11-3
Cache Settings and Operations
11.3
Cache Enable
11.3.1
At initial reset, the caching function is disabled.
Set up as follows to use caching.
When the instruction cache is used
Set the IC/CCU_CFG register to 1.
When the data cache is used
Set the DC/CCU_CFG register to 1.
Turning IC and DC back to 0 flushes and clears all data cached.
Note: Be sure to disable the instruction and data caches before executing the halt or slp instruction.
Selecting Area to Be Cached
11.3.2
The CCU caches access to one area (an external memory) out of Areas 14 to 22. Select a target area for caching
in the instruction cache in ARIC[2:0]/CCU_AREA register and one for caching in the data cache in ARDC[2:0]/
CCU_AREA register, respectively.
3.2.1 Selecting Area to Be Cached
Table 11.
ARIC[2:0]/ARDC[2:0]
Areas to be cached
0x7
Area 22 (0x80000000 to 0xffffffff)
0x6
Area 21 (0x40000000 to 0x7fffffff)
0x5
Area 20 (0x20000000 to 0x3fffffff)
0x4
Area 19 (0x10000000 to 0x1fffffff)
0x3
Area 18 (0x0c000000 to 0x0fffffff)
0x2
Area 17 (0x08000000 to 0x0bffffff)
0x1
Areas 15 and 16 (0x04000000 to 0x07ffffff)
0x0
Area 14 (0x03000000 to 0x03ffffff)
(Default: 0x0)
The CCU only caches access to the range of 64MB starting at the top of the selected area. The areas after the lead-
ing 64MB space in Areas 19 to 22 are mirror areas.
Comparing Addresses and Cache Hit/Mishit
11.3.3
Among addresses output by the SRAMC, two bits at A[7:6] represent the entry number (frame offset). A[25:8] is
deemed as a comparison address and compared with the address for comparison (CA[25:8]) stored in the TAG sec-
tion containing four Ways under the entry selected in A[7:6].