Section 22 PCI Controller (PCIC)
SH7751 Group, SH7751R Group
Page 946 of 1128
R01UH0457EJ0301 Rev. 3.01
Sep 24, 2013
On the other hand, it checks if transfer data exists in the respective FIFOs and reads that data from
the data transfer FIFO in which there is data and which has the highest priority, and outputs that
data to the PCI bus.
For example, if channel 1 FIFO is empty, the arbitration circuit writes the data from the local bus
into the channel 1 FIFO. Next, if data of 32 bytes or more is in the channel 1 FIFO, it outputs that
data to the PCI bus.
If data has been written to both buffers of the channel 1 FIFO, the channel 1 FIFO is busy while
data is output from one of those buffers to the PCI bus. While it is busy, data is written from the
local bus to the channel 2 FIFO, which has the next highest order of priority. When all data has
been output from the channel 1 FIFO to the PCI bus, data is output from the channel 2 FIFO,
which still contains data, to the PCI bus.
Thus, in fixed priority mode, execution alternates between the two data transfers with the highest
priority.
That is, if DMA transfers are performed simultaneously on 4 channels, the data transfers start with
alternation between channels 1 and 2 and then move to alternating between 2 and 3 when all the
data in channel 1 has been transferred. Likewise, execution moves to alternation between channels
3 and 4 on completion of channel 2.
This pattern is the same when data is transferred from the PCI bus to the local bus.
Pseudo round-robin mode (DMABT = 1):
In pseudo round-robin mode, as each time data is
transferred, the order of priority is changed so that the priority level of the completed data transfer
becomes the lowest.
Regarding pseudo round-robin mode operations, refer to section 22.3.5, Host Functions.
22.3.10
Transfer Contention within PCIC
No contention occurs in the PCIC in the case of PIO transfer requests from the CPU and memory
reads/memory writes due to target transfers. This is because PIO transfers use an internal bus for
peripheral modules, and this operates independently of the local bus that has memory accessed by
external PCI devices. Contention can occur in the PCIC in the case of PIO transfer requests from
the CPU and IO reads/IO writes due to target transfers (PCIC local register access). In this case,
however, arbitration is performed in the PCIC such that priority is given to register access by the
external PCI device that has the PCI bus rights.
Содержание SH7751 Group
Страница 2: ...Page ii of liv R01UH0457EJ0301 Rev 3 01 Sep 24 2013 ...
Страница 30: ...Page xxx of liv R01UH0457EJ0301 Rev 3 01 Sep 24 2013 ...
Страница 46: ...Page xlvi of liv R01UH0457EJ0301 Rev 3 01 Sep 24 2013 ...
Страница 54: ...Page liv of liv R01UH0457EJ0301 Rev 3 01 Sep 24 2013 ...
Страница 190: ...Section 4 Caches SH7751 Group SH7751R Group Page 136 of 1128 R01UH0457EJ0301 Rev 3 01 Sep 24 2013 ...
Страница 226: ...Section 5 Exceptions SH7751 Group SH7751R Group Page 172 of 1128 R01UH0457EJ0301 Rev 3 01 Sep 24 2013 ...
Страница 264: ...Section 7 Instruction Set SH7751 Group SH7751R Group Page 210 of 1128 R01UH0457EJ0301 Rev 3 01 Sep 24 2013 ...
Страница 320: ...Section 9 Power Down Modes SH7751 Group SH7751R Group Page 266 of 1128 R01UH0457EJ0301 Rev 3 01 Sep 24 2013 ...
Страница 344: ...Section 10 Clock Oscillation Circuits SH7751 Group SH7751R Group Page 290 of 1128 R01UH0457EJ0301 Rev 3 01 Sep 24 2013 ...
Страница 388: ...Section 12 Timer Unit TMU SH7751 Group SH7751R Group Page 334 of 1128 R01UH0457EJ0301 Rev 3 01 Sep 24 2013 ...
Страница 800: ...Section 17 Smart Card Interface SH7751 Group SH7751R Group Page 746 of 1128 R01UH0457EJ0301 Rev 3 01 Sep 24 2013 ...
Страница 848: ...Section 19 Interrupt Controller INTC SH7751 Group SH7751R Group Page 794 of 1128 R01UH0457EJ0301 Rev 3 01 Sep 24 2013 ...
Страница 876: ...Section 20 User Break Controller UBC SH7751 Group SH7751R Group Page 822 of 1128 R01UH0457EJ0301 Rev 3 01 Sep 24 2013 ...
Страница 1036: ...Section 22 PCI Controller PCIC SH7751 Group SH7751R Group Page 982 of 1128 R01UH0457EJ0301 Rev 3 01 Sep 24 2013 ...
Страница 1152: ...Appendix C Mode Pin Settings SH7751 Group SH7751R Group Page 1098 of 1128 R01UH0457EJ0301 Rev 3 01 Sep 24 2013 ...
Страница 1185: ......
Страница 1186: ... SH7751 Group SH7751R Group User s Manual Hardware R01UH0457EJ0301 Previous Number REJ09B0370 0400 ...