PSB7238 SIEMENS [Siemens Semiconductor Group], PSB7238 Datasheet - Page 174

• Manufacturer Part Number: PSB7238
• Description: Joint Audio Decoder-Encoder - Multimode
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

Semiconductor Group
In this case, the host generates the WCB interrupt before it has recognized the VocFin
from the JADE and the JADE generates the VocFin before it has recognized the WCB
from the host.
Immediately after the reception of WCB request the JADE will service that interrupt and
send the corresponding acknowledge interrupt IND 32
the IND register is overwritten by that. If the host was busy between VocFin and the
acknowledge of WCB, it will only receive one interrupt and recognize the later one, which
is the IND 32
check the “VocoderFinished” backup register 61
toggled, it knows that there has been a VocFin before the IND 32
continue to service it.
Note: A parallel read/write access of the 3061/61 register is not prohibited by hardware.
3. “Read JADE Status” Conflict with “VocoderFinished”, Case 1
If a “Read JADE Status” (RS) interrupt handshake is initiated by the host immediately
before the next time frame starts and is not completed at the time the new VocFin
interrupt should occur, the VocFin is delayed until the RS is finished.
Due to audio delay reasons, the JADE has small internal buffers for the compressed
data. This leads to an overwriting of audio data very soon after a VocFin is delayed.
It is ensured that the JADE is working stable in these situations (except for the 16-kHz
pass-through mode, in which two VocFin handshakes have to be done in each time
frame, see above), nevertheless, a graceful degradation of speech quality has to be
accepted by the user which is about proportional to the real delay time of the VocFin
interrupt (the smaller the delay due to the busy host, the smaller the degradation of
quality).
4. “Read JADE Status” Conflict with “VocoderFinished”, Case 2
A “Read JADE Status” (RS) request from the host coming in parallel with the VocFin of
the new time frame will cause the following interrupt flow:
Thus an invalid value maybe read by the host when it reads the register at the
same time as the JADE writes it. As a consequence, the host has to implement a
double last look regarding this register, i.e. it has to read the contents until it has
read the same value in two consecutive read-accesses, only then it is ensured that
the value is valid.
H
. To recognize, that it has missed one VocFin interrupt, the host should
174
H
. If the value of this register has
H
. The VocFin interrupt status in
Data Sheet 1998-07-01
H
Firmware Features
interrupt and must
PSB 7238