DS26401 datasheet(162/309 Pages) DALLAS

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DS26401 Octal T1/E1/J1 Framer

162

10.6 H.100 (CT Bus) Compatibility

The H.100 (or CT Bus) is a synchronous, bit-serial, TDM transport bus operating at 8.192MHz. The H.100 standard

also allows compatibility modes to operate at 2.048MHz, 4.096MHz, or 8.192MHz. The control bit H100EN

(RIOCR.5), when combined with RSYNCINV and TSSYNCINV allows the DS26401 to accept the CT-Bus

compatible frame sync signal (/CT_FRAME) at the RSYNC and TSSYNC inputs. The following rules apply to the

H100EN control bit:

1) The H100EN bit controls the sampling point for the RSYNC (input mode) and TSSYNC only (the RSYNC output

and other sync signals are not affected).

2) The H100EN bit would always be used in conjunction with the receive and transmit elastic store buffers.

3) The H100EN bit would typically be used with 8.192MHz IBO mode (Section 8.21), but could also be used with

4.096MHz IBO mode or 2.048MHz backplane operation.

4) The H100EN bit in RIOCR controls both RSYNC and TSSYNC (i.e., there is no separate control bit for the

TSSYNC).

5) The H100EN bit does not invert the expected signal, RSYNCINV (RIOCR) and TSSYNCINV (TIOCR) must be

set ‘high’ to invert the inbound sync signals.

Figure 10-1. RSYNC Input in H.100 (CT Bus) Mode

Bit 8

Bit 1

Bit 2

RSYNC1

RSYNC2

RSYSCLK

RSER

NOTE 1: RSYNC INPUT MODE IN NORMAL OPERATION.

NOTE 2: RSYNC INPUT MODE, H100EN = 1 and RSYNCINV = 1.

NOTE 3: tbc (BIT-CELL TIME) = 122ns (typ). tbc = 244ns or 488ns ALSO ACCEPTABLE.

DS26401 Datasheet(PDF) 162 Page - Dallas Semiconductor