PSB7238 SIEMENS [Siemens Semiconductor Group], PSB7238 Datasheet - Page 133

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

3. The JADE reads the new control block from the mailbox, resets the INHB bit and
4. The host may reset the INDB as a reaction to the JADE interrupt. This step is not
Any changes to the current operating mode of the JADE take effect on the next input data
packets, i.e. when a 10 ms frame length is selected, the next 10 ms packet of
uncompressed data will be compressed using the new settings and the next 10 ms
packet of compressed data will be decompressed using the new settings, too.
Due to internal buffering, a three stages pipeline appears in the JADE (input,
compression/decompression, output). Each stage takes as long as determined by the
frame length (default: 10 ms). For that reason, a mode switch affecting the input data of
the JADE has to go through the whole pipeline before the output data reports the new
settings. This results in a delay of three times the frame length (default: 30 ms) between
the host requesting a new mode setting and the JADE delivering the first packet of data
compressed/decompressed with these new settings and reporting the new settings in
the status data block.
To change the control block data, the host must first set the mode to neutral (see MODE
register description below) for at least three frames (default: 30 ms). Although the MODE
word is part of the control block, it can be changed to neutral at any time. The switch to
neutral mode before doing other changes to the control block is required to clear up the
JADE’s pipeline and make sure it does not have to process two different modes at once
in the same pipeline. Following the neutral mode command, the host may transfer the
control block with the new settings.
Some bits in the control block don’t require this procedure (volume change, …). These
are especially indicated in the description of the control block (see below).
See Figure 43 for the host reading the current status data block from the JADE:
The following steps are executed:
1. The host writes new control block into JADE mailbox using the procedure described
2. The host generates an interrupt to the JADE by writing value 31
Semiconductor Group
in Section 3.3.2.2.
status register at address 50
acknowledges the reception by generating an interrupt at INT line to the host by
writing a value 32
mandatory and may be skipped.
H
into IND interrupt status register at address 58
H
.
133
Data Sheet 1998-07-01
Firmware Features
H
H
.
into INH interrupt
PSB 7238