Chapter 8 DMA Controller
8-6
•
Single Address transfer from memory to an external I/O device (DMCCRn.MEMIO = “0”)
External memory Write operation to an address specified by the DMA Source Address
Register (DMSARn) is performed simultaneously to assertion of the DMAACK[n] signal. At
this time, the external I/O device drives the DATA signal instead of the TX4925.
Special attention must be paid to the timing design when the bus clock frequency is high or
when performing Burst transfer. Single Address transfer using Burst transfer with SDRAM is not
recommended.
8.3.3.4 DMADONE
*
Signal
The DMADONE* signal operates as either the DMA stop request input signal or the DMA done
signalling output signal, or may operate as both of these signals depending on the setting of the
DONE Control Field (DNCTRL) of the DMA Channel Control Register (DMCCRn).
The DMADONE* signal is shared by four channels. The DMADONE* channel is valid for a
channel when the DMAACK[n] signal for that channel is asserted.
If the DMADONE* channel is set to be used as an output signal (DMCCRn.DNCTRL = 10/11),
it will operate as follows depending on the setting of the Chain End bit (CHDN) of the DMA
Channel Control Register (DMCCRn).
When the Chain End bit (CHDN) is set, the DMADONE* signal is only asserted when the
DMAACK[n] signal for the last DMA transfer in the Link List Command Chain is asserted.
When the Chain End bit (CHDN) is cleared, the DMADONE* signal is asserted when the
DMAACK[n] signal for the last data transfer in a DMA transfer specified by the current DMA
Channel Register is asserted. Namely, if the Link List Command chain is used, there is one
assertion at the end of each data transfer specified by each Descriptor.
If the DMADONE* signal is set to be used as an input signal (DMCCRn.DNCTRL = 01/11),
DMA transfer can be set to end normally when the external device asserts the DMADONE* signal
when the DMAACK[n] signal of channel
n
is asserted. DMADONE* is asserted during
DMAACK[n] is not asserted, then unexpected operation occurs. When DMA transfer is
terminated by the DMADONE* assertion of the external device, the External DONE Assert bit
(DMCSRn.EXTDN) of the DMA Channel Status Register is set regardless of the setting of the
Chain End bit (CHDN) of the DMA Channel Control Register (DMCCRn). Operation is as
follows depending on the setting of the Chain End bit (CHDN).
When the Chain End bit (CHDN) is set, all DMA transfer for that chain is terminated. At this
time, the Normal Chain End bit (NCHNC) and the Normal Transfer End bit (NTRNFC) of the
DMA Channel Status Register are both set and the Transfer Active bit (DMCCRn.XFACT) of the
DMA Channel Control Register is cleared.
Содержание TMPR4925
Страница 1: ...64 Bit TX System RISC TX49 Family TMPR4925 Rev 3 0 ...
Страница 4: ......
Страница 15: ...Handling Precautions ...
Страница 16: ......
Страница 18: ...1 Using Toshiba Semiconductors Safely 1 2 ...
Страница 40: ...3 General Safety Precautions and Usage Considerations 3 18 ...
Страница 42: ...4 Precautions and Usage Considerations 4 2 ...
Страница 43: ...TMPR4925 ...
Страница 44: ......
Страница 54: ...Chapter 1 Features 1 8 ...
Страница 58: ...Chapter 2 Block Diagram 2 4 ...
Страница 88: ...Chapter 4 Address Mapping 4 12 ...
Страница 226: ...Chapter 8 DMA Controller 8 58 ...
Страница 260: ...Chapter 9 SDRAM Controller 9 34 ...
Страница 480: ...Chapter 15 Interrupt Controller 15 32 ...
Страница 554: ...Chapter 19 Real Time Clock RTC 19 8 ...
Страница 555: ...Chapter 20 Removed 20 1 20 Removed ...
Страница 556: ...Chapter 20 Removed 20 2 ...
Страница 564: ...Chapter 21 Extended EJTAG Interface 21 8 ...
Страница 580: ...Chapter 22 Electrical Characteristics 22 16 ...
Страница 586: ...Chapter 23 Pin Layout Package 23 6 23 2 Package Package Type Package Code 256 pin PBGA PBGA 4L P BGA256 2727 1 27A4 ...
Страница 588: ...Chapter 24 Usage Notes 24 2 ...
Страница 590: ...Appendix A TX49 H2 Core Supplement A 2 ...