Section 14 Direct Memory Access Controller (DMAC)
Rev.1.00 Dec. 13, 2005 Page 588 of 1286
REJ09B0158-0100
14.4 Operation
When there is a DMA transfer request, the DMAC starts the transfer according to the
predetermined channel priority; when the transfer end conditions are satisfied, it ends the transfer.
Transfers can be requested in three modes: auto request, external request, and peripheral module
request. In bus mode, burst mode or cycle steal mode can be selected.
14.4.1
DMA Transfer Requests
DMA transfer requests are basically generated in either the data transfer source or destination, but
they can also be generated by external devices or peripheral modules that are neither the source
nor the destination. Transfers can be requested in three modes: auto request, external request, and
peripheral module request. The request mode is selected in the bits RS[3:0] in CHCR0 to
CHCR11 respectively, and DMARS0 to DMARS2 when peripheral module request is used.
Auto-Request Mode: When there is no transfer request signal from an external source, as in a
memory-to-memory transfer or a transfer between memory and an on-chip module unable to
request a transfer, auto-request mode allows the DMAC to automatically generate a transfer
request signal internally. Specify B'0100 to the RS [3:0] bits in CHCRn (n = 0 to 11) of the using
DMA channel. When the DE bit in CHCR for corresponding channel and the DME bit in
DMAOR0 for channels 0 to 5, DMAOR1 for channels 6 to11 are set to 1, the transfer begins so
long as the AE and NMIF bits in that DMAOR are all 0.
External Request Mode: In this mode, a transfer is performed at the request signal (DREQ) of an
external device. This mode is valid only in channel 0 to 3. Specify B'0000 to the RS [3:0] bits in
CHCRn (n = 0 to 3) of the using DMA channel. When this mode is selected, if the DMA transfer
is enabled (DE = 1, DME = 1, TE = 0, AE = 0, NMIF = 0), a transfer is performed upon a request
at the DREQ input.
Choose to detect DREQ by either the edge or level of the signal input with the DL bit and DS bit
in CHCRn (n = 0 to 3) as shown in table 14.5. The source of the transfer request does not have to
be the data transfer source or destination.
Summary of Contents for SH7780 Series
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Page 122: ...Section 3 Instruction Set Rev 1 00 Dec 13 2005 Page 72 of 1286 REJ09B0158 0100 ...
Page 146: ...Section 4 Pipelining Rev 1 00 Dec 13 2005 Page 96 of 1286 REJ09B0158 0100 ...
Page 196: ...Section 6 Floating Point Unit FPU Rev 1 00 Dec 13 2005 Page 146 of 1286 REJ09B0158 0100 ...
Page 292: ...Section 9 L Memory Rev 1 00 Dec 13 2005 Page 242 of 1286 REJ09B0158 0100 ...
Page 492: ...Section 12 DDR SDRAM Interface DDRIF Rev 1 00 Dec 13 2005 Page 442 of 1286 REJ09B0158 0100 ...
Page 674: ...Section 15 Clock Pulse Generator CPG Rev 1 00 Dec 13 2005 Page 624 of 1286 REJ09B0158 0100 ...
Page 692: ...Section 16 Watchdog Timer and Reset Rev 1 00 Dec 13 2005 Page 642 of 1286 REJ09B0158 0100 ...
Page 726: ...Section 18 Timer Unit TMU Rev 1 00 Dec 13 2005 Page 676 of 1286 REJ09B0158 0100 ...
Page 1032: ...Section 25 Audio Codec Interface HAC Rev 1 00 Dec 13 2005 Page 982 of 1286 REJ09B0158 0100 ...
Page 1150: ...Section 28 General Purpose I O GPIO Rev 1 00 Dec 13 2005 Page 1100 of 1286 REJ09B0158 0100 ...
Page 1184: ...Section 29 User Break Controller UBC Rev 1 00 Dec 13 2005 Page 1134 of 1286 REJ09B0158 0100 ...
Page 1266: ...Section 31 Electrical Characteristics Rev 1 00 Dec 13 2005 Page 1216 of 1286 REJ09B0158 0100 ...
Page 1328: ...Appendix Rev 1 00 Dec 13 2005 Page 1278 of 1286 REJ09B0158 0100 ...
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