Chapter 8 DMA Controller
8-9
During Single Address transfer, the DMA Destination Address Register (DMDARn) and DMA
Destination Address Increment Register (DMDAIRn) settings are ignored.
Table 8.3.2 Channel Register Setting Restrictions During Single Address Transfer
DMSARn[1:0]
Transfer Setting
Size
(DMCCRn.XFSZ)
DMSAIRn is “0” or
greater
DMSAIRn setting is a
negative value
DMSAIRn[1:0] DMCNTRn[1:0]
1 Byte
** **
** **
2 Bytes
*
0
*
1
*
0
*
0
4 Bytes
00
11
00
00
4 Words
8 Words
16 Words
32 Words
00 11
4/0/-4
00
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 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 7 bits of the
Transfer Start address are 0x54 and the transfer setting size (DMCCRn.XFSZ) is set to 4 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 word transfer is performed up to the
address aligned to the transfer setting size. Then, four 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 word transfer
and one word transfer is only performed consecutively without releasing bus ownership when
transfer spans across a 32 word boundary.
Summary of Contents for TMPR4925
Page 1: ...64 Bit TX System RISC TX49 Family TMPR4925 Rev 3 0 ...
Page 4: ......
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: ...TMPR4925 ...
Page 44: ......
Page 54: ...Chapter 1 Features 1 8 ...
Page 58: ...Chapter 2 Block Diagram 2 4 ...
Page 88: ...Chapter 4 Address Mapping 4 12 ...
Page 226: ...Chapter 8 DMA Controller 8 58 ...
Page 260: ...Chapter 9 SDRAM Controller 9 34 ...
Page 480: ...Chapter 15 Interrupt Controller 15 32 ...
Page 554: ...Chapter 19 Real Time Clock RTC 19 8 ...
Page 555: ...Chapter 20 Removed 20 1 20 Removed ...
Page 556: ...Chapter 20 Removed 20 2 ...
Page 564: ...Chapter 21 Extended EJTAG Interface 21 8 ...
Page 580: ...Chapter 22 Electrical Characteristics 22 16 ...
Page 588: ...Chapter 24 Usage Notes 24 2 ...