DS2154
Each Transmit Signaling Register (TS1 to TS16) contains the CAS bits for two timeslots that will be
inserted into the outgoing stream if enabled to do so via TCR1.5. On multiframe boundaries, the DS2154
will load the values present in the Transmit Signaling Register into an outgoing signaling shift register
that is internal to the device. The user can utilize the Transmit Multiframe bit in Status Register 2 (SR2.5)
to know when to update the signaling bits. The bit will be set every 2 ms and the user has 2 ms to update
the TSRs before the old data will be retransmitted. ITU specifications recommend that the ABCD
signaling not be set to all 0s because they will emulate a CAS multiframe alignment word.
The TS1 register is special because it contains the CAS multiframe alignment word in its upper nibble.
The upper nibble must always be set to 0000 or else the terminal at the far end will lose multiframe
synchronization. If the user wishes to transmit a multiframe alarm to the far end, then the TS1.2 bit
should be set to a 1. If no alarm is to be transmitted, then the TS1.2 bit should be cleared. The three
remaining bits in TS1 are the spare bits. If they are not used, they should be set to 1. In CCS signaling
mode, TS1 to TS16 can also be used to insert signaling information. Via the SR2.5 bit, the user will be
informed when the signaling registers need to be loaded with data. The user has 2 ms to load the data
before the old data will be retransmitted.
Via the CCR3.6 bit, the user has the option to use the Transmit Channel Blocking Registers (TCBRs) to
determine, on a channel by channel basis, which signaling bits are to be inserted via the TSRs (the
corresponding bit in the TCBRs=1) and which are to be sourced from the TSER or TSIG pin (the
corresponding bit in the TCBRs=0). See the Transmit Data Flow diagram in Section 13 for more details.
48 of 87
DALLAS [ DALLAS SEMICONDUCTOR ]
