PT7A6632 Datasheet, PDF (10/61 Pages) Pericom Semiconductor Corporation – PT7A6632 32-Channel HDLC Controller

Data Sheet
PT7A6632 32-Channel HDLC Controller
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Transmit Bit-Level Processor
Timing
The block diagram of the Transmit Bit-Level Processor is
shown in Figure 5. The external memory stores data to be trans-
mitted and the channel operation modes in a set of linked
buffers (referred as Transmit Data/Command Buffers) in the
external memory. Refer to Figure 23 and 24 in the External
Memory Organization and Definition.
TCLK clocks data bit stream out at its falling edge. TMAX is
multiframe synchronization signal from the T1/E1 trunk inter-
face. SIS decides the TMAX is sampled in rising or falling
edge of TCLK . PT7A6632 processes data channel by channel
for the data transmission under control of channel counter in
the Transmit Interface. See Figure 7-10.
For transmit, the PT7A6632 reads the data from external
memory, formats it in HDLC format (generates flags, abort and
idle code, inserts zero-bit, counts the Frame Check Sequences),
non-HDLC signaling format or non-HDLC data format, adapts
data rate, and sends the processed data to TSER output via the
Transmit Interface.
Data Rate Adaptation
The PT7A6632 can adapt the data rate of sub-64kb/s (n x 8kb/
s, n = 1 - 8) to the standard 64kb/s bearer rate. A FILL/MASK
byte in the transmit command buffer is applied to the data bit
by bit to perform data rate adaptation. An example is shown in
the Figure 6.
Figure 5. Block Diagram of Transmit Bit-Level Processor
To/From
Memory
Manager
Format
&
Rate Adapt
(32 Channels)
Transmit
Interface
State/Control Signals
TSER
TSEREN
TMAX
TCLK
Figure 6. 32kb/s Subrate Operation - Single Transmit Channel
MSB
LSB
ABCDEFGH
JKLMNOPQ
Data Bytes to Be Transmitted
PT019(05/02)
FILL/MASK Pattern
10111000
FILL/MASK
0 = A fill bit of 1 or high Z (see TSEREN)
1 = Insert bit of data byte starting with LSB
T1/CEPT PCM-30 Serial Output
TS m in Frame n
TS m in Frame n+1 TS m in Frame n+2
1 1 1 H G F 1 E 1 1 1 D C B 1 A 1 1 1 Q P O ...
Transmitted Data
LSB
10
Ver:2