
PSB 7280
Semiconductor Group
50
Data Sheet 1998-07-01
4.2
Audio and Data Reception/Transmission
The PSB 7280 supports a total of eight independent serial I/O-channels:
two receive and two transmit audio channels, and
two receive and two transmit data channels (pertaining to the two HDLC controllers).
The eight channels are transferred between the DSP and/or the parallel host interface
and one of the serial interface lines: DD or DU (IOM-2), or SR or ST (Serial Audio
Interface SAI). The capacity of each channel is individually determined by programming
the time-slot length on the selected serial interface line.
Timing Generation
The selection of the line for each of the channels is performed via SLIN1,0 (00: DU; 01:
DD; 10: SR; 11: ST). The timing logic is driven by the bit clock and frame synchronization
signals corresponding to the selected line. These are:
The IOM-2 timing signals can be input or output of the PSB 7280, i.e. the circuit is a slave
or master with respect to the IOM-2 interface. The selection is done by the CGEN bit in
register 202B
H
.
The timing on the SAI lines SR and ST is either input or output. In the case where the
timing is internally generated (i.e. the PSB 7280 functions as SAI master for SR and/or
ST), a schematic diagram of the generation logic is shown in
Figure 19
.
DCL(/2) and FSC
SCLK and RFS
SCLK and TFS
for DD and DU.
for SR.
for ST.