PSB7238 SIEMENS [Siemens Semiconductor Group], PSB7238 Datasheet - Page 60

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

Semiconductor Group
4.3
The two internal HDLC controllers of the PSB 7238 can be independently serviced
– either via the Parallel Host Interface
– or by the DSP (SPCF).
Important Notes
1. From the point of view of the end user/system manufacturer, only the servicing of the
2. If the packet oriented protocol on the Serial Audio Interface used in videophone
The servicing of the HDLC controller(s) via the host and via the embedded DSP are
exclusive of each other. The access to the register banks of the two HDLC controllers is
determined by the “HDLC Controller Access from Host” bits HAH1 (for HDLC1) and
HAH2 (for HDLC2):
– When HAHx is ‘0’, the SPCF is allowed to access the HDLC register bank, and the
– When HAHx is ‘1’, the host is allowed to access the HDLC register bank, and the
The address spaces of the two HDLC controllers for the host interface bus and for the
SPCF data bus is shown in Figure 25 (see also Section 5: HDLC Controller Register
Description):
Figure 25
HDLC controllers via the host is of relevance, since the servicing via the DSP is done
by on-chip firmware invisible to the end user.
applications with the VCP (from 8 8, Inc.) videocodec is needed, the HDLC1
controller is serviced by the on-chip firmware, in other words, it cannot be accessed
by the host: only HDLC2 controller will then be available to the user.
host interface bus is disconnected from the HDLC controller;
SPCF data bus is disconnected from the HDLC controller.
HDLC Controller
60
Data Sheet 1998-07-01
Functional Blocks
PSB 7238