TrueSpeech® Co-Processor
PRELIMINARY/CONFIDENTIAL
Version: 1.18
The sample filter above (300-640 Hz) was designed with the following parameters:
type 6th order elliptic
lower stop-band cut-off 250 Hz
lower pass-band cut-off 300 Hz
upper pass-band cut-off 640 Hz
upper stop-band cut-off 800 Hz
sample rate
pass band ripple
stop band ripple
8000 Hz
0.1 (1 dB)
0.05 (-26 dB stop band attenuation)
9.20.12 Generating Interrupts from Line Monitor Events
The CT8022 can generate line monitor event interrupts to the Host controller via the Auxiliary Software Status
Register (ASSR). The Host can set an interrupt mask corresponding to the status response bits for the normal line
monitor status response.
Set line monitor status interrupt mask:
C1:
S1:
5148H
5148H
C2/S2 Interrupt Mask:
000X
F3
F2
F2
F0
0
0
DTMF
VALID
CPF
VALID
DTMF
DIGIT
(15-12)
(11)
(10)
(9)
(8)
(7)
(6)
(5)
(4)
(3-0)
Setting a mask bit to “1” will update the ASSR with the current line monitor status, if the corresponding bit in the
line monitor status changes state. If the X bit is set to “1”, the ASSR will be automatically updated every speech
frame period even if there is no change to the line monitor status value.
By default, the line monitor status interrupt mask is set to zero.
To generate a Host interrupt from the line monitor status, the Host should set the Aux Status Update IE bit in the
Hardware Control Register. Reading the ASSR will clear the interrupt.
For interrupt-driven line monitor status updates, the line monitor feature should be operated in asynchronous mode.
For example: to generate an ASSR update on detection of any DTMF digit, use the following command sequence:
C1
S1
C2
S2
5148H
5148H
0020H
0020H
9.20.13 Operating the Line Monitor Detectors On the Outgoing Playback Audio Stream
By default, the Line Monitor detectors operate on the incoming (record) audio stream. However, the CT8022 can be
configured so that the detectors operate on the outgoing (playback) audio stream. This enables the detector to detect
tones and DTMF digits in the decompressed (playback) audio.
To set the Line Monitor detector direction, use the following command.
C1:
S1:
C2:
S2:
5149H
5149H
direction
direction
Set direction=0 for normal operation
Set direction=1 for tone detection on the outgoing (playback) audio stream
140
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 ]
