TrueSpeech® Co-Processor
PRELIMINARY/CONFIDENTIAL
Version: 1.18
2.2
External SRAM CT8022 Connection
All CT8022 configurations require the use of a minimum 8K x 8 external SRAM (32K x 8 is usually less expensive
than 8k x 8, and may also be used).
The CT8022 requires an external memory of 8K x 8 for a data only configuration or 32K x 16 for a combined
program and data configuration that will support download of external software modules. The first 4K x 16 portion
of this memory is used to provide storage for data buffers and other data objects required for normal operation of the
device. In the basic data only configuration, the memory is used only for data storage, with execution of code
occurring from the CT8022’s built-in ROM. This built-in ROM contains all the code required for basic operation of
the CT8022, including the G.723.1 and TrueSpeech 8.5 speech compression code.
The CT8022 is capable of expanding the functionality of the device by the addition of external software modules (for
example, a software coder module for G.729AB). These software modules require external memory. In the 32K x
16 configuration, only the first 4K words are used as data space with the remainder of the space available for
downloaded code.
Refer to the following diagrams.
2.2.1
CT8022 8-Bit External Data Only SRAM Connection
DRDN
DWRN
DCSN
RD
WR
CS
32k/8k x 8
15ns SRAM
CT8022
BSEL, ADDR0-13
ADDRESS 0-14
DATA 0-7
MDB0-7
Figure 2-2:
External Data Only SRAM Connection
This is the basic external memory configuration showing the CT8022 connected to one external data SRAM chip.
This configuration does not support download of external software coder modules.
Note: The BSEL signal is not used in 16-bit wide memory configurations. The connection of the chip select
signal DCSN is optional. It is possible to leave the DCSN signal unconnected with the CS input of the
SRAM connected to GND.
16
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 ]
