TrueSpeech® Co-Processor
PRELIMINARY/CONFIDENTIAL
Version: 1.18
4.5.5
Host Receive and Transmit Data Buffer Blocks
The CT8022 includes two 16-word (32 byte) data buffer blocks for use in transferring blocks of data to or from the
Host. Access to these buffers is controlled by the CT8022. The Host accesses these buffers in sequential address
order through two 16-bit Host Data Buffer access ports (one for RX and one for TX). The Host address sequence is
generated by an internal address counter within the CT8022.
Each buffer is shared between the Host and CT8022. At any one time, either the Host or the CT8022 has access to
the buffer. At no time can both Host and CT8022 access the buffer simultaneously. The CT8022 controls whether
access belongs to the CT8022 or Host via an internal control register. For example, when the Host transmits data to
the CT8022, the CT8022 first grants the Host access to the buffer. The Host fills the empty buffer. While the Host
is filling the buffer, the CT8022 can not access it. Once the buffer is full, the CT8022 regains access to the full
buffer. The CT8022 then copies the data from the buffer. At this point, the Host can not access the buffer. Once the
buffer has been emptied, the CT8022 can then pass it back to the Host.
The receive and transmit buffer blocks are conceptually almost identical except for the direction of data transfer
associated with Host accesses. The receive buffer is used to transfer data from the CT8022 to the Host. The
transmit buffer is used to transfer data from the Host to the CT8022.
4.5.5.1
Host Receive Data Buffer Block
This block is used to transfer data from the CT8022 to the Host, using an external DMA controller or a Host
processor access cycle.
HSTRD
DMA byte
Select
Toggle
Data
Host Access Port
Data
16 x 16
Data Buffer
Address
Address
Counter
Address
Comparator
Internal Control Register
Control
RX Ready
Frame Size
RX Ready
RXDREQ
DMA Logic
Figure 4-2:
Host Receive Data Buffer Block
32
DSP GROUP, INC., 3120 SCOTT BOULEVARD CT8022A11AQC FW Revision 0118
SANTA CLARA, CA 95054 PH: 408 986 – 4300 FAX: 408 986 – 4490
All specifications are subject to change without prior notice.
ETC [ ETC ]
