PSB7238 SIEMENS [Siemens Semiconductor Group], PSB7238 Datasheet - Page 170

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

Semiconductor Group
Note: A polling host should not directly poll the IND interrupt status register 58
Note: Some special situations have to be considered if one uses a slow host that cannot
Interrupt Conflicts with a Slow Host
In the following some special situations and the recommended handling are described
to keep the host protocol stable also in situations where the host has not finished it’s
interrupt requests before the begin of the next time frame, as long as the interrupt service
delay is less than 160 ms.
The following descriptions apply for all encoder/decoder modes, except the 16-kHz
pass-through. In the 16-kHz pass-through mode, the host must ensure that all interrupts
are finished before the next “VocoderFinished” is generated by the JADE. This is
because of the special double-“VocoderFinished” protocol, see text above.
If the interrupt service from the host is delayed by up to 160 ms, none of the Interrupts
during this time (usually only one “VocoderFinished” every 10 ms) is lost, but they are
delayed, too, until the host is able to service them. Thus, after a gap in interrupt service
a burst of interrupts has to be serviced by the host.
Note: G.723 mode: During the interrupt burst to catch up for the delayed host interrupt
The interrupts “Write JADE Control Block” and “Read JADE Status” are representative
for all kinds of interrupts initiated by the host, so they are used in the following as an
example for the corresponding type of interrupt.
1. “Write JADE Control Block” Conflict with “VocoderFinished”, Case 1
A critical situation for the host may occur when a “Write JADE Control Block” (WCB)
interrupt handshake is done immediately before the next time frame starting with the new
“VocoderFinished” (VocFin) interrupt begins. See Figure 50.
DINT bit in INT interrupt status register 75
interrupt from the DSP has been generated or not, independently of the
corresponding mask register. The mask register only decides whether an interrupt
at INT line is generated. After having recognized an IND interrupt status, the
polling host may read out the register 58
always ensure to finish the whole interrupt handshake in one frame period (default
10 ms), i.e. before the next VocoderFinished interrupt is generated by the JADE.
Collisions between not finished interrupts and the new VocoderFinished Interrupt
may occur.
service, the number of interrupts ensures proper synchronisation after the burst,
but the data and packet numbering during the burst will be garbage. Thus, the
synchronisation of encoder and decoder packets should only be done during
non-delayed interrupt service.
170
H
to get the interrupt number.
H
. This bit always shows whether an
Data Sheet 1998-07-01
Firmware Features
PSB 7238
H
, but the