TrueSpeech® Co-Processor
PRELIMINARY/CONFIDENTIAL
Version: 1.18
25. Repeat steps 22-24 until all (16) data words are transferred
26. CT8022 de-asserts DATAFLAG/ signal to indicate the end of data transfer
27. Optional: Host waits for DATAFLAG/ to be de-asserted
28. Repeat steps 13-27 until recording finished
To end recording, Host writes Idle command or Record Stop command and waits for status response.
Note: Bold text indicates the record software data transfer loop. By default, The DATAFLAG signal on
external pin GPIO0 is disabled. Refer to Section 9.25 for more information regarding GPIO pins.
9.7.5
Select TrueSpeech/G.723.1 Record Rate
This command allows the Host to select the TrueSpeech data rate used in Compressed Record mode. The standard
(built-in) available CT8022 rates are TrueSpeech 6.3, 5.3, 4.8 and 4.1. This command should be issued prior to
starting record using the Record command. The TrueSpeech Record Rate remains in effect until the next
TrueSpeech Record Rate command.
Command (513XH):
0101
0001
0011
(7-4)
RATE
(3-0)
(15-12)
(11-8)
Status (513XH):
0101
0001
0011
(7-4)
RATE
(3-0)
(15-12)
(11-8)
RATE
TrueSpeech Compression Rate
Compressed Frame Size (16-bit words)
0
1
2
16
12
10
9
8.5 (see Note)
6.3 (G.723.1) (default)
5.3 (G.723.1)
4.8
3
4
4.1
8
5
Reserved
6
6 (10ms)
G.729AB (see Note)
G.722 (see Note)
Reserved
7
40 (10ms)
8-15
The Frame Size value indicates the number of 16-bit words in a compressed speech frame for each coding rate.
When any of the TrueSpeech compression rates is selected, the frame size is always 16 words or less. Since the size
of the CT8022 hardware buffer within the Host port is 16 words, the Host can burst read the complete speech frame
of 16-8 words without checking the RX Ready bit before each individual word is read. Where the frame size is
larger than 16 words, the CT8022 splits the data transfer into sub-blocks of 16 words or less.
Note: The CT8022 supports the G.729-A/B and G.722 coders only as external downloadable software
expansion modules. The Host must ensure that the appropriate module is loaded to the CT8022
external program/data memory before attempting to activate any of these coders. Contact DSP
Group for details on availability for these coders.
64
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 ]
