Chapter 8 DMA Controller
8-11
8.3.7.2 Burst Transfer During Single Address Transfer
According to the SDRAM Controller and External Bus Controller specifications, the DMA
Controller cannot perform Burst transfer that spans across 32-double word boundaries.
Consequently, if the address that starts DMA transfer is not a multiple of the transfer setting size
(DMCCRn.XFSZ) (is not aligned), transfer cannot be performed by any of the transfer sizes that
were specified by a Burst transfer. Therefore, the DMA Controller executes multiple Burst
transactions of a transfer size smaller than the specified transfer size. This division method
changes according to the seting of the Transfer Size Mode bit (DMCCRn.USEXFSZ) of the DMA
Channel Control Register.
Figure 8.3.2 shows the Single Address Burst transfer status when the lower 8 bits of the
Transfer Start address are 0xA8 and the transfer setting size (DMCCRn.XFSZ) is set to 4 double
words.
Panel (a) of this figure shows the situation when the Transfer Size Mode bit
(DMCCRn.USEXFSZ) is “0”. In this case, first a three-double word transfer is performed up to
the address aligned to the transfer setting size. Then, four-double word transfer specified by the
transfer setting size is repeated. This setting is normally used.
On the other hand, panel (b) shows when the Transfer Size Mode bit (DMCCRn.USEXFSWZ)
is “1”. In this case, transfer is repeated according to the transfer setting size. Three-double word
transfer and one-double word transfer is only performed consecutively without releasing bus
ownership when transfer spans across a 32-double word boundary.
(a) DMCCRn.USEXFSZ
=
“0”
(b) DMCCRn.USEXFSZ
=
“1”
Figure 8.3.2 Non-aligned Single Address Burst Transfer
a0
a8
b0
b8
c8
d0
d8
c0
e8
f0
f8
e0
00
08
10
18
28
30
38
20
48
50
58
40
60
3 Double Words
4 Double Words
4 Double Words
4 Double Words
4 Double Words
4 Double Words
DMCCRn.XFER
=
4
32 Double Word Boundary
63
0
a0
a8
b0
b8
c8
d0
d8
c0
e8
f0
f8
e0
00
08
10
18
28
30
38
20
48
50
58
40
60
4 Double Words
4 Double Words
(3
+
1) Double Words
4 Double Words
4 Double Words
DMCCRn.XFER
=
4
63
0
4 Double Words
Summary of Contents for TX49 TMPR4937
Page 1: ...64 Bit TX System RISC TX49 Family TMPR4937 Rev 2 0 ...
Page 4: ......
Page 13: ...Table of Contents ix TMPR4937 Revision History 1 ...
Page 14: ...Table of Contents x ...
Page 15: ...Handling Precautions ...
Page 16: ......
Page 18: ...1 Using Toshiba Semiconductors Safely 1 2 ...
Page 40: ...3 General Safety Precautions and Usage Considerations 3 18 ...
Page 42: ...4 Precautions and Usage Considerations 4 2 ...
Page 43: ...TMPR4937 2005 3 Rev 2 0 ...
Page 44: ......
Page 52: ...Chapter 1 Overview and Features 1 6 ...
Page 156: ...Chapter 7 External Bus Controller 7 56 ...
Page 491: ...Chapter 16 Removed 16 1 16 Removed ...
Page 492: ...Chapter 16 Removed 16 2 ...
Page 493: ...Chapter 17 Removed 17 1 17 Removed ...
Page 494: ...Chapter 17 Removed 17 2 ...
Page 495: ...Chapter 18 Removed 18 1 18 Removed ...
Page 496: ...Chapter 18 Removed 18 2 ...
Page 497: ...Chapter 19 Removed 19 1 19 Removed ...
Page 498: ...Chapter 19 Removed 19 2 ...
Page 506: ...Chapter 20 Extended EJTAG Interface 20 8 ...
Page 530: ...Chapter 22 Pinout and Package Information 22 10 ...
Page 542: ...Chapter 24 Parts Number when Ordering 24 2 ...