PSB7238 SIEMENS [Siemens Semiconductor Group], PSB7238 Datasheet - Page 55

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

The start of the transmission can be in the same frame (w.r.t. the frame sync signal on
the chosen line) as the setting of XAC = 1 and/or the writing to the HXW1/2 register since
the time-slot logic works independently of XAC.
In transparent mode (TMO = 1) the transmission is only started at the beginning of the
time-slot (time-slot aligned). If the first write to HXW1/2 happens during the selected
time-slot, the transmitter waits for the beginning of the time-slot in the next frame.
Transmitter in LMOD = 00
The same applies for LMOD = 00, except the post-processing is not available. The data
from the HDLC transmitter is after XAC = 1 directly passed through the bit-reversal unit
into the shift register. In addition, the loading of HXR1/2, HXW1/2 and the generation of
the interrupt is done like in the other LMODs for observation of the data stream by the
DSP or host only. Thus, the LMOD = 00 is identical with LMOD = 01, except
post-processing is not available and the transmitter latency after reset is shortened, see
section below. The transmission is in this case started by the setting of XAC = 1. No write
to HXW1/2 is necessary.
The start of the transmission can be in the same frame (w.r.t. the frame sync signal on
the chosen line) as the setting of XAC = 1 since the time-slot logic works independently
of XAC.
In transparent mode (TMO = 1) the transmission is only started at the beginning of the
time-slot (time-slot aligned). If XAC is set to ‘1’ during the selected time-slot, the
transmitter waits for the beginning of the time-slot in the next frame.
The HDLC/transparent data channel registers, each of length 2 words/4 bytes, are (see
Section 3):
HRR1
HRR2
HRW1
HRW2
HXR1
HXR2
HXW1
HXW2
Semiconductor Group
HDLC Receive Read 1.
HDLC Receive Read 2.
HDLC Receive Write 1.
HDLC Receive Write 2.
HDLC Transmit Read 1.
HDLC Transmit Read 2.
HDLC Transmit Write 1.
HDLC Transmit Write 2.
55
Data Sheet 1998-07-01
Functional Blocks
PSB 7238