Hitachi 149
Figure 7.15 indicates an example of the basic cycle. Because a slower synchronous DRAM is
connected, setting the WCR and MCR bits can extend the cycle. The number of cycles from the
ACTV command output cycle Tr to the READA command output cycle Tc can be specified by the
RCD bit of the MCR. 0 specifies 1 cycle; 1 specifies 2 cycles. For 2 cycles, a NOP command issue
cycle Trw for the synchronous DRAM is inserted between the Tr cycle and the Tc cycle. The
number of cycles between the READA command output cycle Tc and the initial read data fetch
cycle Td1 can be specified independently for areas CS2 and CS3 between 1 cycle and 4 cycles
using the W21/W20 and W31/W30 bits of the WCR. The CAS latency when using bus arbitration
in the partial-share master mode can be set differently for CS2 and CS3 spaces. The number of
cycles at this time corresponds to the number of CAS latency cycles of the synchronous DRAM.
When 2 cycles or more, a NOP command issue cycle Tw is inserted between the Tc cycle and the
Td1 cycle. The number of cycles in the precharge completion waiting cycle Tap is specified by the
TRP bit of the MCR. When the CAS latency is 1, a Tap cycle of 1 or 2 cycles is generated. When
the CAS latency is 2 or more, a Tap cycle equal to the TRP specification – 1 is generated. During
the Tap cycle, no commands other than NOP are issued to the same bank. Figure 7.16 shows an
example of burst read timing when RCD is 1, W31/W30 is 01, and TRP is 1.
With the synchronous DRAM cycle, when the bus cycle starts in the ordinary space access, the BS
signal asserted for 1 cycle is asserted in each of cycles Td1–Td4 for the purpose of the external
address monitoring described in the section on bus arbitration. When another CS space is accessed
after an synchronous DRAM read with a wait between buses specification of 0, the BS signal may
be continuously asserted. The address is updated every time data is fetched while burst reads are
being performed. The burst transfer unit is 16 bytes, so address updating affects A3–A1. The
access order follows address order in 16-byte data transfers by the DMAC, but reading starts from
the a 4 so that the last missed data in the fill operation after a cache miss can be read.
When the data width is 16 bits, 8 burst cycles are required for a 16-byte data transfer. The data
fetch cycle goes from Td1 to Td8. From Td1 to Td8, the BS signal is asserted in every cycle.
Synchronous DRAM CAS latency is up to 3 cycles, but the CAS latency of the bus state controller
can be specified up to 4. This is so that circuits containing latches can be installed between
synchronous DRAMs and the SH7095.
Summary of Contents for SH7095
Page 1: ...SH7095 Hardware User Manual ...
Page 23: ...12 Hitachi ...
Page 63: ...52 Hitachi ...
Page 77: ...66 Hitachi ...
Page 105: ...94 Hitachi Figure 5 14 Pipeline Operation when Interrupts are Enabled by Changing the SR ...
Page 127: ...116 Hitachi ...
Page 152: ...Hitachi 141 Figure 7 8 Example of 32 Bit Data Width SRAM Connection ...
Page 157: ...146 Hitachi Figure 7 13 Synchronous DRAM 32 bit Device Connection ...
Page 161: ...150 Hitachi Figure 7 15 Basic Burst Read Timing Auto Precharge ...
Page 167: ...156 Hitachi Figure 7 20 Burst Read Timing Bank Active Same Row Address ...
Page 168: ...Hitachi 157 Figure 7 21 Burst Read Timing Bank Active Different Row Addresses ...
Page 169: ...158 Hitachi Figure 7 22 Write Timing No Precharge ...
Page 170: ...Hitachi 159 Figure 7 23 Write Timing Bank Active Same Row Address ...
Page 180: ...Hitachi 169 Figure 7 29 Example of a DRAM Connection 32 Bit Data Width ...
Page 190: ...Hitachi 179 Figure 7 36 Example of Pseudo SRAM Connection 1 M pseudo SRAM ...
Page 191: ...180 Hitachi Figure 7 37 Example of Pseudo SRAM Connection 4 M pseudo SRAM ...
Page 209: ...198 Hitachi Figure 7 50 Master and Partial Share Master Connections ...
Page 231: ...220 Hitachi ...
Page 287: ...276 Hitachi ...
Page 307: ...296 Hitachi Note For a CPU writing H AA55 to FRC Figure 11 2 FRC Access Operation Write ...
Page 308: ...Hitachi 297 Note For an FRC reading from a CPU H AA55 Figure 11 3 FRC Access Operation Read ...
Page 333: ...322 Hitachi ...
Page 370: ...Hitachi 359 Figure 13 12 Sample Flowchart for Receiving Multiprocessor Serial Data ...
Page 371: ...360 Hitachi Figure 13 12 Sample Flowchart for Receiving Multiprocessor Serial Data cont ...
Page 395: ...384 Hitachi ...
Page 402: ...Hitachi 391 Figure 15 6 PLL Synchronization Settling Timing ...
Page 408: ...Hitachi 397 Figure 15 13 Bus Release Timing Slave Mode With PLL1 Off ...
Page 436: ...Hitachi 425 Figure 15 33 Synchronous DRAM Mode Register Write Cycle TRP 1 Cycle ...
Page 437: ...426 Hitachi Figure 15 34 Synchronous DRAM Mode Register Write Cycle TRP 2 Cycles ...
Page 449: ...438 Hitachi Figure 15 46 DRAM CAS Before RAS Refresh Cycle TRP 1 Cycle TRAS 2 Cycles PLL On ...
Page 454: ...Hitachi 443 Figure 15 51 DRAM CAS Before RAS Refresh Cycle TRP 1 Cycle TRAS 2 Cycles PLL Off ...
Page 461: ...450 Hitachi Figure 15 58 Pseudo SRAM Auto Refresh Cycle PLL On TRP 1 Cycle TRAS 2 Cycles ...
Page 462: ...Hitachi 451 Figure 15 59 Pseudo SRAM Self Refresh Cycle PLL On TRP 1 Cycle TRAS 2 Cycles ...
Page 467: ...456 Hitachi Figure 15 64 Pseudo SRAM Auto Refresh Cycle PLL Off TRP 1 Cycle TRAS 2 Cycles ...
Page 468: ...Hitachi 457 Figure 15 65 Pseudo SRAM Self Refresh Cycle PLL Off TRP 1 Cycle TRAS 2 Cycles ...
Page 471: ...460 Hitachi Figure 15 68 Interrupt Vector Fetch Cycle PLL On No Waits ...
Page 472: ...Hitachi 461 Figure 15 69 Interrupt Vector Fetch Cycle PLL Off No Waits ...
Page 473: ...462 Hitachi Figure 15 70 Interrupt Vector Fetch Cycle 1 External Wait Cycle ...
Page 474: ...Hitachi 463 Figure 15 71 Address Monitor Cycle ...
Page 490: ...Hitachi 479 B 2 Register Chart ...