2.0 Functional Description
CN8223
2.2 Line Framers
ATM Transmitter/Receiver with UTOPIA Interface
2.2.3 Externally Framed Transmit Line Interface
In external framer mode, the transmitter inputs are a clock and a synchronization
signal that indicate the position of framing bits in the DS1, E1, DS3, or E3
framing signal. The transmit data stream output is a single serial output. The
synchronization signal period can be any multiple of the frame period.
Functional timing for the transmit line interface is similar for all external
framer modes. These interfaces are compatible with Conexant framers Bt8360 for
DS1, Bt8510 for E1, Bt8370 for E1/T1, and Bt8330B for DS3 and E3. Interface
connections for these serial, external framing modes are given in Table 2-6.
Table 2-6. Serial External Framer Transmitter Interface Connection
Signal Name
Connect to CN8223 Pin
Transmit Clock Input (TXCKI)
Transmit Sync Input (TXSYI)
Transmit Data Output (TXDATO)
TXCKI
TXIN
TXOUT[3]
Figure 2-7 illustrates the transmit timing for the DS1 interface. TXCKI is
1.544 MHz. TXSYI has a rising edge prior to the sampling of the frame bit. This
signal does not have to be present at every frame; in particular, it can be a
superframe synchronization signal with a period of 3 ms. TXDATO is the output
signal; it transitions in response to the rising edge of TXCKI and can be sampled
on the following falling edge. The framing bit position content in the output
stream is undefined.
Figure 2-7. DS1 Interface Transmit Timing
TXCKI
TXSYI
TXDATO
7
8
S
2
3
4
5
6
7
8
F
S
2
3
4
5
6
7
Channel 24
Channel 1
2-8
Conexant
100046C
CONEXANT [ CONEXANT SYSTEMS, INC ]
