
PSB 7280
Semiconductor Group
25
Data Sheet 1998-07-01
Channels
The following channels may be programmed on the IOM-2 interface: two receive audio
channels, two transmit audio channels, one monitor channel, two C/I channels, two
receive and two transmit HDLC channels:
The transfer of voice samples is performed with the help of an interrupt with repetition
rate 8 kHz derived from the FSC signal. A double-buffered register is provided for each
channel, accessible from the DSP and from the parallel host interface. The double
buffered register ensures that enough time is always provided for reading and writing
data before an overflow/underflow occurs, independent of the location of the time-slots.
Alternatively, the audio samples can be transferred between the DSP or Host and IOM-2
by using an interrupt generated when a programmable number (1
…
32) of bits are shifted
out (number independent of the time-slot length on the line).
Outside the time-slots where transmission takes place the DU and DD lines are in high
impedance.
Audio receive 1 and receive 2 channels
Audio transmit 1 and transmit 2 channels
Independently programmable on DD or
DU, with programmable locations (start
at bit 1
…
512) and lengths (1
…
32 bits)
w.r.t. FSC
Programmable on DD(in)/DU(out) or
DD(out)/DU(in), with programmable
time-slot (3rd byte in multiplex 0,
…
, 15)
after FSC
Programmable on DD(in)/DU(out) or
DD(out)/DU(in), with programmable
length (4 or 6 bits) and position (4
th
byte
in multiplex 0,
…
, 15) after FSC
Independently programmable on DD or
DU, with programmable locations (start
at bit 1
…
512) and lengths (1
…
256 bits)
w.r.t. FSC
Monitor channel
Two C/I channels
Two HDLC receive and transmit channels