DS26518 Datasheet, PDF (71/312 Pages) Maxim Integrated Products – 8-Port T1/E1/J1 Transceiver

DS26518 8-Port T1/E1/J1 Transceiver
9.9.15 T1 Programmable In-Band Loop Code Generator
The DS26518 can generate and detect a repeating bit pattern from one to eight bits or 16 bits in length. This
function is available only in T1 mode.
Table 9-33. Registers Related to T1 In-Band Loop Code Generator
REGISTER
Transmit Code Definition Register 1
(T1TCD1)
Transmit Code Definition Register 2
(T1TCD2)
Transmit Control Register 3 (TCR3)
FRAMER 1
ADDRESSES
1ACh
1ADh
183h
FUNCTION
Pattern to be sent for loop code.
Length of the pattern to be sent.
TLOOP bit for control of number of patterns being
sent.
Transmit Control Register 4 (TCR4)
186h
Length of the code being sent.
Note: The addresses shown above are for Framer 1. Addresses for Framers 2 to 8 can be calculated using the following: Framer n = (Framer 1
address + (n - 1) x 200hex), where n = 2 to 8 for Framers 2 to 8.
To transmit a pattern, the user will load the pattern to be sent into the Transmit Code Definition Registers (T1TCD1
and T1TCD2) and select the proper length of the pattern by setting the TC0 and TC1 bits in Transmit Control
Register 4 (TCR4). When generating a 1-, 2-, 4-, 8-, or 16-bit pattern both T1TCD1 and T1TCD2 must be filled with
the proper code. Generation of a 3-, 5-, 6-, and 7-bit pattern only requires T1TCD1 to be filled. Once this is
accomplished, the pattern will be transmitted as long as the TLOOP control bit (TCR3.0) is enabled. Normally
(unless the transmit formatter is programmed to not insert the F-bit position) the framer will overwrite the repeating
pattern once every 193 bits to allow the F-bit position to be sent.
As an example, to transmit the standard “loop-up” code for Channel Service Units (CSUs), which is a repeating
pattern of ...10000100001..., set TCD1 = 80h, TC0 = 0, TC1 = 0, and TCR3.0 = 1.
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