Version: 1.18
PRELIMINARY/CONFIDENTIAL
TrueSpeech® Co-Processor
4.6.3
Flow-Through DMA Transfers
Programmer’s Note:
A Flow-Through DMA transfer is one in which the read and write operations of the DMA transfer
take place as separate cycles, with the DMA controller providing intermediate temporary storage of
the data. In this type of DMA, the data physically flows through the DMA controller:
•
•
•
•
•
DMA controller outputs source address
DMA controller reads from source
DMA controller stores data in internal temporary register (single byte)
DMA controller outputs destination address
DMA controller writes data to destination
Address
Data
CT8022 RX Buffer Addr
Data From 8022
Destination Memory Addr.
Data From 8022
RDN
WRN
RXDREQ
HSTCS/
RXDACK/
Figure 4-6:
Flow-Through DMA
Figure 4-6 is an example of a CT8022 to Memory DMA transfer using Flow-Through DMA. The RXDACK/ signal
is not used. Note that, from the perspective of the CT8022, an access by a Flow-Through type DMA controller
looks identical to a normal Host access. The Intel 80186 and 80188 processors contain this type of DMA controller.
CT8022A11AQC FW Revision 0118 DSP GROUP, INC., 3120 SCOTT BOULEVARD
SANTA CLARA, CA 95054 PH: 408 986 – 4300 FAX: 408 986 – 4490
39
All specifications are subject to change without prior notice.
ETC [ ETC ]
