XRT72L71 Datasheet, PDF (8/102 Pages) Exar Corporation – DS3 ATM UNI/CLEAR CHANNEL FRAMER

XRT72L71
DS3 ATM UNI/CLEAR CHANNEL FRAMER
REV. 1.1.0
PIN DESCRIPTIONS (SEE FIGURE 3)
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PIN DESCRIPTION
PIN NO.
1
SYMBOL
D15
2
TAOS
3
D14
4
D13
5
D12
6
DMO
7
MOTO/Intel
TYPE
I/O
O
I/O
I
I
DESCRIPTION
MSB of Bi-Directional Data Bus (Microprocessor Interface Section): This
pin, along with pins D0 - D14, function as the Microprocessor Interface bi-direc-
tional data bus, and is intended to be interfaced to the “local” microprocessor.
This pin is inactive if the Microprocessor Interface block is configured to oper-
ate over an 8 bit data bus.
“Transmit All Ones Signal” (TAOS) Command (for the XRT7300 LIU IC).
This output pin is intended to be connected to the TAOS input pin of the XR-
T7300 LIU IC. The user can control the state of this output pin by writing a ‘0’
or ‘1’ to Bit 4 (TAOS) within the Line Interface Drive Register (Address = 0x72).
If the user commands this signal to toggle "High" then it will force the
XRT7300 DS3 Line Transmitter IC to transmit an "All Ones" pattern onto the
line. Conversely, if the user commands this output signal to toggle "Low" then
the XRT7300 DS3 Line Transmitter IC will proceed to transmit data based upon
the pattern that it receives via the TxPOS and TxNEG output pins.
Writing a "1" to Bit 4 of the Line Interface Drive Register (Address = 0x72) will
cause this output pin to toggle "High". Writing a "0" to this bit-field will cause
this output pin to toggle "Low".
NOTE: If the designer is not using the XRT7300 DS3/E3/STS-1 LIU IC, then
this output pin can be used for other purposes.
Bi-directional Data bus (Microprocessor Interface Section): This pin is
inactive if the Microprocessor Interface block is configured to operate over an
8 bit data bus. Please see description for D15, pin 1.
“Drive Monitor Output” Input (from the XRT7300 LIU IC): This input pin is
intended to be tied to the DMO output pin of the XRT7300 E3/DS3/STS-1 LIU
IC. The user can determine the state of this input pin by reading Bit 2 (DMO)
within the Line Interface Scan Register (Address = 0x73). If this input signal is
“High”, then it means that the drive monitor circuitry (within the XRT7300 LIU
IC) has not detected any bipolar signals at the MTIP and MRING inputs within
the last 128 ± 32 bit-periods. If this input signal is “Low”, then it means that
bipolar signals are being detected at the MTIP and MRING input pins of the
XRT7300.
NOTE: If the designer is not using the XRT7300 E3/DS3/STS-1 LIU IC, then
this input pin can be used for other purposes.
Motorola/Intel Processor Interface Select Mode: This input pin allows the
user to configure the Microprocessor Interface to interface with either a “Motor-
ola-type” or “Intel-type” microprocessor/microcontroller. Tying this input pin to
VDD, configures the microprocessor interface to operate in the Motorola mode
(e.g., the UNI/Framer can be readily interfaced to a “Motorola type” local
microprocessor). Tying this input pin to GND configures the microprocessor
interface to operate in the Intel Mode (e.g., the UNI/Framer can be readily inter-
faced to an “Intel type” local microprocessor).
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