Datasheet

DS26521 Single T1/E1/J1 Transceiver
185 of 258
Register Name:
TCR3
Register Description:
Transmit Control Register 3
Register Address:
183h
Bit # 7 6 5 4 3 2 1 0
Name
ODF ODM TCSS1 TCSS0 MFRS TFM IBPV TLOOP
ODF ODM TCSS1 TCSS0 MFRS — IBPV CRC4R
Default 0 0 0 0 0 0 0 0
Bit 7: Output Data Format (ODF).
0 = bipolar data at TTIP and TRING
1 = NRZ data at TTIP; TRING = 0
Bit 6: Output Data Mode (ODM).
0 = pulses at TTIP and TRING are one full TCLK period wide
1 = pulses at TTIP and TRING are one-half TCLK period wide
Bits 5 and 4: Transmit Clock Source Select 1 and 0 (TCSS[1:0]).
TCSS1 TCSS0 TRANSMIT CLOCK SOURCE
0 0 The TCLK pin is always the source of transmit clock.
0 1
Switch to the clock present at RCLK when the signal at the TCLK pin fails to transition after
one channel time.
1 0 Reserved
1 1 Use the signal present at RCLK as the transmit clock. The TCLK pin is ignored.
Bit 3: Multiframe Reference Select (MFRS). This bit selects the source for the transmit formatter multiframe
boundary.
0 = Normal operation. Transmit multiframe boundary is determined by line-side counters referenced to
TSYNC when TSYNC is an input. Free-running when TSYNC is an output.
1 = Pass-forward operation. Transmit multiframe boundary determined by system-side counters referenced
to TSSYNCIO (input mode 3), which is then passed forward to the line-side clock domain. This mode can
only be used when the transmit elastic store is enabled with a synchronous backplane (i.e., no frame slips
allowed). This mode must be used to allow transmit hardware-signaling insertion while the transmit elastic
store is enabled.
Bit 2: Transmit Frame Mode Select (TFM) (T1 Mode Only).
0 = ESF framing mode
1 = D4 framing mode
Bit 1: Insert BPV (IBPV). A 0-to-1 transition on this bit will cause a single bipolar violation (BPV) to be inserted into
the transmit data stream. Once this bit has been toggled from 0 to 1, the device waits for the next occurrence of
three consecutive ones to insert the BPV. This bit must be cleared and set again for a subsequent error to be
inserted.
Bit 0 (T1 Mode): Transmit Loop Code Enable (TLOOP). See Section
8.9.15 for details.
0 = transmit data normally
1 = replace normal transmitted data with repeating code as defined in registers
T1TCD1 and T1TCD2
Bit 0 (E1 Mode): CRC-4 Recalculate (CRC4R).
0 = transmit CRC-4 generation and insertion operates in normal mode
1 = transmit CRC-4 generation operates according to G.706 Intermediate Path Recalculation method