Hitachi 201
Data cannot be written from the DMAC to cache memory. When the DMAC causes a write to
memory, the contents of memory and the cache contents will be different. To rewrite the contents
of memory, the cache memory must be purged with software if the possibility exists that the data
for that address exists in the cache.
When the CPU starts a read access to a cache area, it first takes a cycle to find the cache. If there is
data in the cache, it fetches it and completes the access. If there is no data in the cache, cache data
is filled via the internal bus, so four consecutive longword reads occur. Misses that occur when
byte or word operands are accessed or branches occur to odd word boundaries (4n + 2 addresses)
are always filled in by longword accesses on the chip-external interface. In the cache-through area,
the access is to the actual access address. When the access is an instruction fetch, the access size is
always longword.
For cache-through areas and on-chip peripheral module read cycles, after an extra cycle is added
to determine the cycle, the read cycle is started through the internal bus. Read data is sent to the
CPU through the cache bus.
When word write cycles access cache area, the cache is searched for. When the data of said
address is found, it is written here. In parallel to this, the actual writing occurs through the internal
bus. When it has the right to use the Internal bus, it notifies the CPU that the write is completed
without waiting for the actual writing to the on-chip peripheral module or off the chip to end.
When it does not have the right to use the internal bus, as when it is being used by the DMAC or
the like, it waits until it gets the bus before notifying the CPU of completion.
Accesses to cache-through areas and on-chip peripheral modules work the same as in the cache
area, except for the cache search and write.
Because the bus state controller has one level of write buffer, the internal bus can be used for
another access even when the chip-external bus cycle has not ended. After a write has been
performed to low-speed memory off the chip, performing a read or write with an on-chip
peripheral module enables an access to the on-chip peripheral module without having to wait for
the completion of the write to low-speed memory.
During reads, the CPU always has to wait for the end of the operation. To immediately continue
processing after checking that the write to the device of actual data has ended, perform a dummy
read access to the same address consecutively to check that the write has ended.
The bus state controller’s write buffer functions the same way during accesses from the DMAC. A
dual-address DMA transfer thus starts up in the next read cycle without waiting for the end of the
write cycle. When both the source address and destination address of the DMA are external spaces
to the chip, however, it must wait until the completion of the previous write cycle before starting
the next read cycle.
Содержание SH7095
Страница 1: ...SH7095 Hardware User Manual ...
Страница 16: ...Hitachi 5 1 2 Block Diagram Figure 1 1 is a block diagram of the SH7095 Figure 1 1 Block Diagram ...
Страница 23: ...12 Hitachi ...
Страница 63: ...52 Hitachi ...
Страница 77: ...66 Hitachi ...
Страница 105: ...94 Hitachi Figure 5 14 Pipeline Operation when Interrupts are Enabled by Changing the SR ...
Страница 127: ...116 Hitachi ...
Страница 152: ...Hitachi 141 Figure 7 8 Example of 32 Bit Data Width SRAM Connection ...
Страница 157: ...146 Hitachi Figure 7 13 Synchronous DRAM 32 bit Device Connection ...
Страница 161: ...150 Hitachi Figure 7 15 Basic Burst Read Timing Auto Precharge ...
Страница 167: ...156 Hitachi Figure 7 20 Burst Read Timing Bank Active Same Row Address ...
Страница 168: ...Hitachi 157 Figure 7 21 Burst Read Timing Bank Active Different Row Addresses ...
Страница 169: ...158 Hitachi Figure 7 22 Write Timing No Precharge ...
Страница 170: ...Hitachi 159 Figure 7 23 Write Timing Bank Active Same Row Address ...
Страница 178: ...Hitachi 167 a Phase Shifted 90 by PLL b Phase Shift Using PLL is 0 Figure 7 28 Phase Shift with the PLL ...
Страница 180: ...Hitachi 169 Figure 7 29 Example of a DRAM Connection 32 Bit Data Width ...
Страница 190: ...Hitachi 179 Figure 7 36 Example of Pseudo SRAM Connection 1 M pseudo SRAM ...
Страница 191: ...180 Hitachi Figure 7 37 Example of Pseudo SRAM Connection 4 M pseudo SRAM ...
Страница 209: ...198 Hitachi Figure 7 50 Master and Partial Share Master Connections ...
Страница 218: ...Hitachi 207 EX Instruction execution MA Memory Access WB Write back Figure 8 3 Reading during a Cache Hit ...
Страница 231: ...220 Hitachi ...
Страница 287: ...276 Hitachi ...
Страница 307: ...296 Hitachi Note For a CPU writing H AA55 to FRC Figure 11 2 FRC Access Operation Write ...
Страница 308: ...Hitachi 297 Note For an FRC reading from a CPU H AA55 Figure 11 3 FRC Access Operation Read ...
Страница 333: ...322 Hitachi ...
Страница 370: ...Hitachi 359 Figure 13 12 Sample Flowchart for Receiving Multiprocessor Serial Data ...
Страница 371: ...360 Hitachi Figure 13 12 Sample Flowchart for Receiving Multiprocessor Serial Data cont ...
Страница 395: ...384 Hitachi ...
Страница 402: ...Hitachi 391 Figure 15 6 PLL Synchronization Settling Timing ...
Страница 405: ...394 Hitachi Figure 15 7 Reset Input Timing Figure 15 8 Interrupt Signal Input Timing With PLL1 Off ...
Страница 408: ...Hitachi 397 Figure 15 13 Bus Release Timing Slave Mode With PLL1 Off ...
Страница 436: ...Hitachi 425 Figure 15 33 Synchronous DRAM Mode Register Write Cycle TRP 1 Cycle ...
Страница 437: ...426 Hitachi Figure 15 34 Synchronous DRAM Mode Register Write Cycle TRP 2 Cycles ...
Страница 439: ...428 Hitachi Figure 15 36 Synchronous DRAM Auto Refresh Cycle Shown From Precharge Cycle TRP 1 Cycle TRAS 2 Cycles ...
Страница 449: ...438 Hitachi Figure 15 46 DRAM CAS Before RAS Refresh Cycle TRP 1 Cycle TRAS 2 Cycles PLL On ...
Страница 454: ...Hitachi 443 Figure 15 51 DRAM CAS Before RAS Refresh Cycle TRP 1 Cycle TRAS 2 Cycles PLL Off ...
Страница 461: ...450 Hitachi Figure 15 58 Pseudo SRAM Auto Refresh Cycle PLL On TRP 1 Cycle TRAS 2 Cycles ...
Страница 462: ...Hitachi 451 Figure 15 59 Pseudo SRAM Self Refresh Cycle PLL On TRP 1 Cycle TRAS 2 Cycles ...
Страница 467: ...456 Hitachi Figure 15 64 Pseudo SRAM Auto Refresh Cycle PLL Off TRP 1 Cycle TRAS 2 Cycles ...
Страница 468: ...Hitachi 457 Figure 15 65 Pseudo SRAM Self Refresh Cycle PLL Off TRP 1 Cycle TRAS 2 Cycles ...
Страница 471: ...460 Hitachi Figure 15 68 Interrupt Vector Fetch Cycle PLL On No Waits ...
Страница 472: ...Hitachi 461 Figure 15 69 Interrupt Vector Fetch Cycle PLL Off No Waits ...
Страница 473: ...462 Hitachi Figure 15 70 Interrupt Vector Fetch Cycle 1 External Wait Cycle ...
Страница 474: ...Hitachi 463 Figure 15 71 Address Monitor Cycle ...
Страница 490: ...Hitachi 479 B 2 Register Chart ...