mt90502ag2 Zarlink Semiconductor, mt90502ag2 Datasheet - Page 101

• Manufacturer Part Number: mt90502ag2
• Description: Multi-channel Aal2 Sar
• Manufacturer: Zarlink Semiconductor

2.10
2.10.1
HDLC data format accommodates data that needs a larger bandwidth than PCM. Any number from 1 to 128
consecutive time slots on a single H.100/H.110 stream can carry data as one HDLC stream thus allowing a higher
data transfer rate. Note that an HDLC stream must be contained within one frame and TX and RX HDLC streams
carrying the same channel do not have to be of the same length.
2.10.2
The MT90502 can accept or generate an HDLC header that contains 0, 1, or 2 address bytes, as well as a possible
control byte that follows the flag. There is also an optional 16-bit CRC that may be added at the end of the packet.
The different formats are illustrated in Figure 64 on page 102. The formats are specified for each stream using the
“Header Type” and “CRC” fields in the HDLC CPS-Packet Assembly Structure (see Figure 13 on page 40 and
Figure 14 on page 41). When using HDLC streams, the low byte of the address is used to select the channel
number. All address bytes that are not used to indicate a channel number are discarded by the TX TDM module.
The payload gamut of an HDLC CPS-Packet is 1 to 64-bytes.
Data is accumulated until a flag is received signifying the end of an HDLC packet. The payload will be processed
according to the HDLC type. The MT90502 supports 2 types of HDLC data over the TDM bus: bit-wide form and
byte-wide form (registers 400h and 500h).
Table 33, “HDLC Packet Formats and Header Types,” on page 103 shows the supported HDLC package formats
with corresponding header types as shown in Figure 13. The CRC selection is also made according to Figure 13.
Using packaing_type (500h bit-3) enables “Raw” AAL2 CPS-Packets to be sent, as described in Section 2.2.3.4. If
there are not multiple HDLC channels in a HDLC stream then SCS will not be used and the address bytes will be
discarded. If SCS is used then the address bytes will be used along with the HDLC stream number to calculate the
HDLC channel number.
HDLC
HDLC Overview
HDLC Format
Zarlink Semiconductor Inc.
MT90502
101
Data Sheet