DS26521 datasheet(45/258 Pages) MAXIM

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DS26521 Single T1/E1/J1 Transceiver

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8.9.4.1 Transmit-Signaling Operation

There are two methods to provide transmit-signaling data. These are processor based (i.e., software based) or

hardware based. Processor based refers to access through the transmit-signaling registers, TS1:TS16, while

hardware based refers to using the TSIG pins. Both methods can be used simultaneously.

8.9.4.1.1 Processor-Based Signaling

In processor-based mode, signaling data is loaded into the transmit-signaling registers (TS1:TS16) via the host

interface. On multiframe boundaries, the contents of these registers are loaded into a shift register for placement in

the appropriate bit position in the outgoing data stream. The user can use the transmit multiframe interrupt in

Latched Status Register 1 (TLS1.2) to know when to update the signaling bits. The user need not update any

transmit-signaling register for which there is no change of state for that register.

Each transmit-signaling register contains the robbed-bit signaling (TCR1.4 in T1 mode) or TS16 CAS signaling

(TCR1.6 in E1 mode) for one time slot that will be inserted into the outgoing stream. Signaling data can be sourced

from the TS registers on a per-channel basis by using the software-signaling insertion enable registers,

SSIE1:SSIE4.

In T1 ESF framing mode, there are four signaling bits per channel (A, B, C, and D). TS1:TS12 contain a full

multiframe of signaling data. In T1 D4 framing mode, there are only two signaling bits per channel (A and B). In T1

D4 framing mode, the framer uses A and B bit positions for the next multiframe. The C and D bit positions become

“don’t care” in D4 mode.

In E1 mode, TS16 carries the signaling information. This information can be in either CCS (common-channel

signaling) or CAS (channel-associated signaling) format. The 32 time slots are referenced by two different channel

number schemes in E1. In channel numbering, TS0 to TS31 are labeled channels 1 to 32. In phone channel

numbering, TS1 to TS15 are labeled channel 1 to channel 15, and TS17 to TS31 are labeled channel 15 to

channel 30.

8.9.4.2 Time Slot Numbering Schemes

9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

Channel

9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

Phone

Channel

9 10 11 12 13 14 15

16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

8.9.4.2.1 Hardware-Based Signaling

In hardware-based mode, signaling data is input via the TSIG pin. This signaling PCM stream is buffered and

inserted to the data stream being input at the TSER pin.

Signaling data can be input via the transmit hardware-signaling channel select (THSCS1) function. The framer can

be set up to take the signaling data presented at the TSIG pin and insert the signaling data into the PCM data

stream that is being input at the TSER pin. The user can control which channels are to have signaling data from the

TSIG pin inserted into them on a per-channel basis. The signaling insertion capabilities of the framer are available

whether the transmit-side elastic store is enabled or disabled. If the elastic store is enabled, the backplane clock

(TSYSCLK) can be either 1.544MHz or 2.048MHz.

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