PSB7238 SIEMENS [Siemens Semiconductor Group], PSB7238 Datasheet - Page 160

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

Semiconductor Group
The basic structure of data exchange between the host and the JADE is for all
compression modes the same, except for the 16-kHz pass-through mode. Thus, two
different cases have to be considered:
Figure 45
The picture shows the sequence of basic handshake procedures for one 10 ms frame.
Basically, in both cases there are three blocks: The compressed audio exchange (basic
procedure 1/3), the uncompressed audio exchange (basic procedure 2/3) and the
finishing procedure (basic procedure 3/3).
The compressed audio exchange (1/3) is executed only once in a 10 ms frame, except
of the 16-kHz pass-through mode. In the 16-kHz pass-through mode the mailbox cannot
transfer the full data packet (320 or 336 bytes, depends on whether outband or inband
control is selected) at once. Only for this mode the interrupt handshake procedure (1/3)
is executed twice in one time frame. With the first run 256 bytes are transmitted in each
direction, with the second run 64 bytes (outband control) or 80 bytes (inband control) are
transmitted.
With the uncompressed audio handshake (2/3), 2.5 ms of uncompressed data are
exchanged (20 samples for 8 kHz and 40 samples for 16-kHz sampling rate). This
results in a four times repetition of this block to collect 10 ms of uncompressed data for
the next frame.
Finally, a finishing handshake (3/3) is executed, which acknowledges the audio data
exchange, offers the possibility to the host to request for other interrupt services and
starts the next frame.
Note: The first time frame after the Host/Host interface has been setup starts with the
last part of the finishing handshake procedure (3/3), see Figure 46 and table
below.
160
Data Sheet 1998-07-01
Firmware Features
PSB 7238