DS26528DK Maxim Integrated Products, DS26528DK Datasheet - Page 52

• Manufacturer Part Number: DS26528DK
• Description: KIT DESIGN FOR DS26528
• Manufacturer: Maxim Integrated Products

Specifications of DS26528DK

• Main Purpose: Telecom, Framer and Line Interface Units (LIUs)
• Utilized Ic / Part: G575DS26528
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Secondary Attributes: -
• Embedded: -
• Primary Attributes: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

DS26528 Octal T1/E1/J1 Transceiver
8.9.4.3 Receive-Signaling Operation
There are two methods to access receive-signaling data and provide transmit-signaling data: processor based (i.e.,
software based) or hardware based. Processor based refers to access through the transmit- and receive-signaling
registers, RS1:RS16. Hardware based refers to the RSIG pin. Both methods can be used simultaneously.
8.9.4.3.1 Processor-Based Signaling
Signaling information is sampled from the receive data stream and copied into the receive-signaling registers,
RS1:RS16. The signaling information in these registers is always updated on multiframe boundaries. This function
is always enabled.
8.9.4.3.2 Change of State
To avoid constant monitoring of the receive-signaling registers, the DS26528 can be programmed to alert the host
when any specific channel or channels undergo a change of their signaling state.
RSCSE1:RSCSE4
are used to
select which channels can cause a change-of-state indication. The change of state is indicated in Latched Status
Register 4 (RLS4.3). If signaling integration is enabled, the new signaling state must be constant for three
multiframes before a change-of-state indication is indicated. The user can enable the INTB pin to toggle low upon
detection of a change in signaling by setting the interrupt mask bit RIM4.3. The signaling integration mode is global
and cannot be enabled on a channel-by-channel basis.
The user can identity which channels have undergone a signaling change of state by reading the receive-signaling
status (RSS1:RSS4) registers. The information from these registers tells the user which RSx register to read for the
new signaling data. All changes are indicated in the RSS1:RSS4 registers regardless of the
RSCSE1:RSCSE4
registers.
8.9.4.3.3 Hardware-Based Receive Signaling
In hardware-based signaling, the signaling data can be obtained from the RSER pin or the RSIG pin. RSIG is a
signaling PCM stream output on a channel-by-channel basis from the signaling buffer. The T1 robbed bit or E1
TS16 signaling data is still present in the original data stream at RSER. The signaling buffer provides signaling data
to the RSIG pin and also allows signaling data to be reinserted into the original data stream in a different alignment
that is determined by a multiframe signal from the RSYNC pin. In this mode, the receive elastic store can be
enabled or disabled. If the receive elastic store is enabled, the backplane clock (RSYSCLK) can be either
1.544MHz or 2.048MHz. In the ESF framing mode, the ABCD signaling bits are output on RSIG in the lower nibble
of each channel. The RSIG data is updated once a multiframe (3ms for T1 ESF, 1.5ms for T1 D4, 2ms for E1 CAS)
unless a signaling freeze is in effect. In the D4 framing mode, the AB signaling bits are output twice on RSIG in the
lower nibble of each channel. Thus, bits 5 and 6 contain the same data as bits 7 and 8, respectively, in each
channel.
8.9.4.3.4 Receive-Signaling Reinsertion at RSER
In this mode, the user provides a multiframe sync at the RSYNC pin and the signaling data will be reinserted based
on this alignment. In T1 mode, this results in two copies of the signaling data in the RSER data stream. The original
signaling data is based on the Fs/ESF frame positions, and the realigned data is based on the user-supplied
multiframe sync applied at RSYNC. In voice channels, this extra copy of signaling data is of little consequence.
Reinsertion can be avoided in data channels since this feature is activated on a per-channel basis. For reinsertion,
the elastic store must be enabled; for T1, the backplane clock can be either 1.544MHz or 2.048MHz. E1 signaling
information cannot be reinserted into a 1.544MHz backplane.
Signaling-reinsertion mode is enabled on a per-channel basis by setting the receive-signaling reinsertion channel
select bit high in the Receive-Signaling Reinsertion Enable register (RSI1:RSI4). The channels that are to have
signaling reinserted are selected by writing to the
RSI1:RSI4
registers. In E1 mode, the user generally selects all
channels or none for reinsertion.
8.9.4.3.5 Force Receive-Signaling All Ones
In T1 mode, the user can, on a per-channel basis, force the robbed-bit signaling bit positions to 1. This is done by
using the T1-mode Receive-Signaling All-Ones Insertion registers (T1RSAOI1:T1RSAOI3). The user sets the
channel select bit in the
T1RSAOI1:T1RSAOI3
registers to select the channels that are to have the signaling forced
to one.
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