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DS21354/DS21554 3.3V/5V E1 Single-Chip Transceivers
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CCR1: COMMON CONTROL REGISTER 1 (Address = 14 Hex)
(MSB)
(LSB)
FLB THDB3 TG802 TCRC4 RSM RHDB3
RG802 RCRC4
SYMBOL
POSITION
NAME AND DESCRIPTION
FLB CCR1.7
Framer Loopback.
0 = loopback disabled
1 = loopback enabled
THDB3 CCR1.6
Transmit HDB3 Enable.
0 = HDB3 disabled
1 = HDB3 enabled
TG802 CCR1.5
Transmit G.802 Enable.
See Section
for details.
0 = do not force TCHBLK high during bit 1 of time slot 26
1 = force TCHBLK high during bit 1 of time slot 26
TCRC4 CCR1.4
Transmit CRC4 Enable.
0 = CRC4 disabled
1 = CRC4 enabled
RSM CCR1.3
Receive Signaling Mode Select.
0 = CAS signaling mode
1 = CCS signaling mode
RHDB3 CCR1.2
Receive HDB3 Enable.
0 = HDB3 disabled
1 = HDB3 enabled
RG802 CCR1.1
Receive G.802 Enable.
See Section
for details.
0 = do not force RCHBLK high during bit 1 of time slot 26
1=force RCHBLK high during bit 1 of time slot 26
RCRC4 CCR1.0
Receive CRC4 Enable.
0 = CRC4 disabled
1 = CRC4 enabled
5.3.
Framer Loopback
When CCR1.7 is set to one, the DS21354/DS21554 enter a framer loopback (FLB) mode. See
for more details. This loopback is useful in testing and debugging applications. In FLB, the SCT will loop
data from the transmit side back to the receive side. When FLB is enabled, the following will occur:
1) Data will be transmitted as normal at TPOSO and TNEGO.
2) Data input via RPOSI and RNEGI will be ignored.
3) The RCLK output will be replaced with the TCLK input.