Section 14 Direct Memory Access Controller (DMAC)
Rev. 1.00 Oct. 01, 2007 Page 600 of 1956
REJ09B0256-0100
(2) Bus
Modes
There are two bus modes: cycle steal mode and burst mode. Select the mode in the TB and LCKN
bits in CHCR. And cycle steal mode has normal and intermittent modes that are specified by the
CMS bits in DMAOR.
•
Cycle-Steal Mode
Normal mode1 (DMAOR.CMS = 00, CHCR.LCKN = 0, CHCR.TB = 0)
In cycle-steal normal mode, the SuperHyway bus mastership is given to another bus master
after a one-transfer unit (byte, word, longword, 16-byte, or 32-byte unit) DMA transfer.
When the next transfer request occurs, the DMAC issues the next transfer request, the bus
mastership is obtained from the other bus master and a transfer is performed for one-
transfer unit. When that transfer ends, the bus mastership is passed to the other bus master.
This is repeated until the transfer end conditions are satisfied.
In cycle-steal normal mode, transfer areas are not affected regardless of settings of the
transfer request source, transfer source, and transfer destination.
Figure 14.6 shows an example of DMA transfer timing in cycle-steal normal mode. Transfer
conditions shown in the figure are:
CPU
CPU
CPU
DMAC
DMAC
CPU
DMAC
DMAC
CPU
DREQ
SuperHyway
bus cycle
Bus mastership returned to CPU once
Read/Write
Read/Write
Figure 14.6 DMA Transfer Timing Example in Cycle-Steal Normal Mode 1
(DREQ Low Level Detection)
Normal mode 2 (DMAOR.CMS = 00, CHCR.LCKN = 1, CHCR.TB = 0)
In cycle steal normal mode 2, the DMAC does not keep the SuperHyway bus mastership, is
to obtain the bus mastership in every one transfer unit of read or write cycle.
Figure 14.7 shows an example of DMA transfer timing in cycle steal normal mode 2.
Summary of Contents for SH7763
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Page 122: ...Section 2 Programming Model Rev 1 00 Oct 01 2007 Page 56 of 1956 REJ09B0256 0100 ...
Page 144: ...Section 3 Instruction Set Rev 1 00 Oct 01 2007 Page 78 of 1956 REJ09B0256 0100 ...
Page 170: ...Section 4 Pipelining Rev 1 00 Oct 01 2007 Page 104 of 1956 REJ09B0256 0100 ...
Page 282: ...Section 7 Caches Rev 1 00 Oct 01 2007 Page 216 of 1956 REJ09B0256 0100 ...
Page 378: ...Section 9 Interrupt Controller INTC Rev 1 00 Oct 01 2007 Page 312 of 1956 REJ09B0256 0100 ...
Page 514: ...Section 12 DDR SDRAM Interface DDRIF Rev 1 00 Oct 01 2007 Page 448 of 1956 REJ09B0256 0100 ...
Page 630: ...Section 13 PCI Controller PCIC Rev 1 00 Oct 01 2007 Page 564 of 1956 REJ09B0256 0100 ...
Page 710: ...Section 16 Clock Pulse Generator CPG Rev 1 00 Oct 01 2007 Page 644 of 1956 REJ09B0256 0100 ...
Page 732: ...Section 17 Watchdog Timer and Reset WDT Rev 1 00 Oct 01 2007 Page 666 of 1956 REJ09B0256 0100 ...
Page 752: ...Section 18 Power Down Mode Rev 1 00 Oct 01 2007 Page 686 of 1956 REJ09B0256 0100 ...
Page 772: ...Section 19 Timer Unit TMU Rev 1 00 Oct 01 2007 Page 706 of 1956 REJ09B0256 0100 ...
Page 824: ...Section 21 Compare Match Timer CMT Rev 1 00 Oct 01 2007 Page 758 of 1956 REJ09B0256 0100 ...
Page 1124: ...Section 26 I 2 C Bus Interface IIC Rev 1 00 Oct 01 2007 Page 1058 of 1956 REJ09B0256 0100 ...
Page 1350: ...Section 30 SIM Card Module SIM Rev 1 00 Oct 01 2007 Page 1284 of 1956 REJ09B0256 0100 ...
Page 1484: ...Section 33 Audio Codec Interface HAC Rev 1 00 Oct 01 2007 Page 1418 of 1956 REJ09B0256 0100 ...
Page 1560: ...Section 35 USB Host Controller USBH Rev 1 00 Oct 01 2007 Page 1494 of 1956 REJ09B0256 0100 ...
Page 1720: ...Section 37 LCD Controller LCDC Rev 1 00 Oct 01 2007 Page 1654 of 1956 REJ09B0256 0100 ...
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