r8a77850anbg Renesas Electronics Corporation., r8a77850anbg Datasheet - Page 687

• Manufacturer Part Number: r8a77850anbg
• Description: Renesas 32-bit Risc Microcomputer Superh? Risc Engine Family
• Manufacturer: Renesas Electronics Corporation.

13. PCI Controller (PCIC)
(2)
Target Read/Write Cycle Timing
The PCIC returns retries to target memory read accesses from an external master until 8 longword
(32-bit) data are prepared in the PCIC internal FIFO. That is, the first target read is always
responded by a retry.
When a target memory write access is performed for the PCIC, the PCIC returns retries to all
subsequent target memory accesses until the write data is completely written to local memory.
Thus, the data contents are guaranteed when data written to the target is target-read immediately
after it was written.
Only single transfers are supported for target accesses to the configuration space and I/O space. If
a burst access request is issued, the external master is disconnected when the first transfer is
complete. Note that the DEVSEL response speed is fixed to 2 clocks (medium) for the target
access to the PCIC.
Figure 13.23 shows an example of a target single-read cycle in normal mode. Figure 13.24 shows
an example of a target single-write cycle in normal mode. Figure 13.25 shows an example of a
target burst-read cycle in host mode. Figure 13.26 shows an example of a target burst-write cycle
in host mode.
Rev.1.00 Jan. 10, 2008 Page 657 of 1658
REJ09B0261-0100