DS26519 datasheet(45/310 Pages) MAXIM

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DS26519 16-Port T1/E1/J1 Transceiver

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9.8.1.4 Receiving Mapped T1 Channels from a 2.048MHz Backplane

Setting the TSCLKM bit in TIOCR.4 enables the transmit elastic store to operate with a 2.048MHz backplane (32

time slots / frame). In this mode the user can choose which of the backplane channels on TSERn will be mapped

into the T1 data stream by programming the Transmit Blank Channel Select registers (TBCS1–4). A logic 1 in the

associated bit location forces the transmit elastic store to ignore backplane data for that channel. Typically the user

will want to program eight channels to be ignored. The default (power-up) configuration will ignore channels 25–32,

so that the first 24 backplane channels are mapped into the T1 transmit data stream.

For example, if the user desired to transmit data from the 2.048MHz backplane channels 2–16 and 18–26, the

TBCS registers should be programmed as follows:

TBCS1 = 01h :: ignore backplane channel 1 ::

TBCS2 = 00h

TBCS3 = 01h :: ignore backplane channel 17 ::

TBCS4= FCh :: ignore backplane channels 27–32 ::

9.8.1.5 Mapping T1 Channels onto a 2.048MHz Backplane

Setting the RSCLKM bit in RIOCR.4 will enable the receive elastic store to operate with a 2.048MHz backplane (32

time slots/frame). In this mode the user can choose which of the backplane channels on RSERn receive the T1

data by programming the Receive Blank Channel Select registers (RBCS1–4). A logic 1 in the associated bit

location will force RSERn high for that backplane channel. Typically the user will want to program eight channels to

be blanked. The default (power-up) configuration will blank channels 25 to 32, so that the 24 T1 channels are

mapped into the first 24 channels of the 2.048MHz backplane. If the user chooses to blank channel 1 (TS0) by

setting RBCS1.0 = 1, then the F-bit will be passed into the MSB of TS0 on RSERn.

For example, if:

RBCS1 = 01h

RBCS2 = 00h

RBCS3 = 01h

RBCS4 = FCh

Then on RSERn:

Channel 1 (MSB) = F-bit

Channel 1 (bits 1-7) = all ones

Channels 2-16 = T1 channels 1-15

Channel 17 = all ones

Channels 18-26 = T1 channels 16-24

Channels 27-32 = all ones

Note that when two or more sequential channels are chosen to be blanked, the receive slip zone select bit should

be set to zero. If the blank channels are distributed (such as 1, 5, 9, 13, 17, 21, 25, 29), the RSZS bit can be set to

one, which can provide a lower occurrence of slips in certain applications.

If the two-frame elastic buffer either fills or empties, a controlled slip will occur. If the buffer empties, then a full

frame of data will be repeated at RSERn and the RLS4.5 and RLS4.6 bits will be set to a one. If the buffer fills, then

a full frame of data will be deleted and the RLS4.5 and RLS4.7 bits will be set to a one.

9.8.1.6 Receiving Mapped E1 Transmit Channels from a 1.544MHz Backplane

The user can use the TSCLKM bit in TIOCR.4 to enable the transmit elastic store to operate with a 1.544MHz

backplane (24 channels / frame + F-bit). In this mode the user can choose which of the E1 time slots will have all-

ones data inserted by programming the Transmit Blank Channel Select registers (TBCS1–4). A logic 1 in the

associated bit location will cause the elastic store to force all ones at the outgoing E1 data for that channel.

Typically the user will want to program eight channels to be blanked. The default (power-up) configuration will blank

channels 25 to 32, so that the first 24 E1 channels are mapped from the 24 channels of the 1.544MHz backplane.

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