Section 14 Direct Memory Access Controller (DMAC)
SH7751 Group, SH7751R Group
Page 554 of 1128
R01UH0457EJ0301 Rev. 3.01
Sep 24, 2013
1. Normal data transfer mode (channel 0)
BAVL
(the data bus available signal) is asserted in response to
DBREQ
(the data bus request
signal) from an external device. Two CKIO-synchronous cycles after
BAVL
is asserted, the
external data bus drives the data transfer setting command (DTR command) in synchronization
with
TR
(the transfer request signal). The initial settings are then made in the DMAC channel
0 control register, and the DMA transfer is processed.
2. Normal data transfer mode (except channel 1 to channel 3)
In this mode, the data transfer settings are made in the DMAC from the CPU, and DMA
transfer requests only are performed from the external device.
As in 1 above,
DBREQ
is asserted from the external device and the external bus is secured,
then the DTR command is driven.
The transfer request channel can be specified by means of the two ID bits in the DTR
command.
3. Handshake protocol using the data bus (valid for channel 0 only)
This mode is only valid for channel 0.
After the initial settings have been made in the DMAC channel 0 control register, the DDT
module asserts a data transfer request for the DMAC by setting the DTR command ID = 00,
MD = 00, and SZ
≠
101, 110 and driving the DTR command.
4. Handshake protocol without use of the data bus
The DDT module includes a function for recording the previously asserted request channel. By
using this function, it is possible to assert a transfer request for the channel for which a request
was asserted immediately before, by asserting
TR
only from an external device after a transfer
request has once been made to the channel for which an initial setting has been made in the
DMAC control register (DTR command and data transfer setting by the CPU in the DMAC).
5. Direct data transfer mode (valid for channel 2 only)
A data transfer request can be asserted for channel 2 by asserting
DBREQ
and
TR
simultaneously from an external device after the initial settings have been made in the DMAC
channel 2 control register.
Содержание SH7751 Group
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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 ...
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