r5s72060w200fpv Renesas Electronics Corporation., r5s72060w200fpv Datasheet - Page 374

• Manufacturer Part Number: r5s72060w200fpv
• Description: 32-bit Risc Microcomputer Superhtm Risc Engine Family / Sh7200 Series
• Manufacturer: Renesas Electronics Corporation.

Section 8 Bus State Controller (BSC)
Sample Estimation of Idle Cycles between Access Cycles
This example estimates the idle cycles for data transfer from the CS1 space to CS2 space by CPU access. Transfer is
repeated in the following order: CS1 read → CS1 read → CS2 write → CS2 write → CS1 read → ...
• Conditions
The idle cycles generated under each condition are estimated for each pair of access cycles. In the following table,
R indicates a read cycle and W indicates a write cycle.
Rev. 2.00 Dec. 09, 2005 Page 350 of 1152
REJ09B0191-0200
The bits for setting the idle cycles between access cycles in CS1BCR and CS2BCR are all set to 0.
(CS negation is not extended).
also 32 bits.
In CS1WCR and CS2WCR, the WM bit is set to 1 (external WAIT pin disabled) and the HW[1:0] bits are set to 00
Iφ:Bφ is set to 4:1, and no other processing is done during transfer.
For both the CS1 and CS2 spaces, normal SRAM devices are connected, the bus width is 32 bits, and access size is
[1] or [2]
[3] or [4]
[5]
[6]
[7]
[5] + [6] + [7]
[8]
Estimated idle
cycles
Actual idle
cycles
Condition
Figure 8.55 Comparison between Estimated Idle Cycles and Actual Value
R → R
0
0
1
0
0
1
0
1
1
R → W
0
0
1
2
1
4
0
4
4
W → W
0
0
0
2
0
2
0
2
2
W → R
0
0
0
0
0
0
0
0
1
CSnBCR is set to 0.
The WM bit is set to 1.
Generated after a read cycle.
See the Iφ:Bφ = 4:1 columns in table 8.19.
No idle cycle is generated for the second time due to the
write buffer effect.
Value for SRAM → SRAM access
Maximum value among conditions [1] or [2], [3] or [4],
[5] + [6] + [7], and [8]
The estimated value does not match the actual value in
the W → R cycles because the internal idle cycles due to
condition [6] is estimated as 0 but actually an internal idle
cycle is generated due to execution of a loop condition
check instruction.
Note