TrueSpeech® Co-Processor
READY
PRELIMINARY/CONFIDENTIAL
Version: 1.18
If the READY flag is set in the status response, the CT8022 expects that immediately following the S1 response, the
Host will transfer 240 words (480 bytes) of uncompressed data. When the Host receives a status response with the
READY flag set, it must immediately commence the transfer of uncompressed speech data.
Host-to-Host Decompression Data Transfer [3] and [4]
Host starts decompression process [3] by issuing decompression C1 command, and waits for Status Ready bit in the
Hardware Status Register to be asserted.
CT8022 acknowledges start of decompression with decompression S1 response.
Host reads S1 status, Status Ready is cleared (Since no data has been decompressed at this time, the READY flag
will not be set).
Host sends playback C2 and C3 commands
Once decompression has been started, the Host transfers compressed data to the CT8022 [3] using the normal
playback data transfer protocol.
Subsequent decompressed speech is transferred using the decompression C1 command. The S1 status - READY
flag is used to control the transfers:
Host sends decompression C1 command
CT8022 returns S1 status response including READY flag.
IF the READY flag is set:
Host transfers decompressed data by writing the dummy decompression command F000H to the Software Control
register and then waiting for STATUS READY to be set. Each time STATUS READY is set, the Host must read the
Software Status Register in order to clear STATUS READY. The data read from the Software Status Register is the
decompressed data. The Host writes the F000H command 240 times in order to read 240 data words from the
Software Status Register.
The playback protocol used to transfer compressed speech data frames to the CT8022 also supports the Buffer
Monitoring, Frame Create, Frame Delete, and Playback Stop commands.
Host-to-Host decompression can be terminated either using the Playback Stop command or the Idle command. One
of these commands should be issued during the command-status sequence in place of the playback C2 command.
Decompression READY polling
Instead of using the decompression S1 status READY response to determine if the CT8022 is ready with more
uncompressed speech data, the Host can poll the READY state using the following command:
command:
status:
5219H
0000H
0001H
if CT8022 is ready to provide more uncompressed data.
if CT8022 is NOT ready to provide more uncompressed data.
This command is only valid if decompression mode is active.
The advantage this command offers over simple use of the decompression C1-S1 command-status, is that it allows
the Host to query the READY state without immediately committing to performing the data transfer. With the
decompression C1-S1 command-status, if the READY bit in the S1 status response is set, the Host must immediately
transfer data.
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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 ]
