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XRT7302IV View Datasheet(PDF) - Exar Corporation

Part Name
Description
MFG CO.
XRT7302IV
Exar
Exar Corporation Exar
'XRT7302IV' PDF : 62 Pages View PDF
XRT7302 2 CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT
REV. P1.1.6
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PRELIMINARY
Bit D3 - STS-1/(DS3_(n)) - Channel(n) - Mode Se-
lect
This Read/Write bit field is used to configure Chan-
nel(n) to operate in either the SONET STS-1 Mode or
the DS3 Mode.
Writing a "0" into this bit-field configures Channel(n)
to operate in the DS3 Mode. Writing a "1" into this
bit-field configures Channel(n) to operate in the SO-
NET STS-1 Mode.
NOTE: This bit-field is ignored if the E3_Ch(n) bit-field (e.g.,
D2 in this Command Register) is set to "1".
Bit D2 - E3 Mode Select - Channel(n)
This Read/Write bit-field is used to configure Chan-
nel(n) to operate in the E3 Mode.
Writing a "0" into this bit-field configures Channel(n)
to operate in either the DS3 or SONET STS-1 Mode
as specified by the setting of the DS3 bit-field in this
Command Register. Writing a "1" into this bit-field
configures Channel(n) to operate in the E3 Mode.
Bit D1 - LLB(n) (Local Loop-Back - Channel(n))
This Read/Write bit-field along with RLB(n) is used to
configure Channel(n) to operate in any one of a vari-
ety of Loop-Back modes.
Table 8 relates the contents of LLB(n) and RLB(n)
and the corresponding Loop-Back mode for Chan-
nel(n).
Bit D0 - RLB(n) (Remote Loop-Back - Channel(n))
This Read/Write bit-field along with LLB(n) is used to
configure Channel(n) to operate in any one of a vari-
ety of Loop-Back modes.
Table 8 relates the contents of LLB(n) and RLB(n)
and the corresponding Loop-Back mode for Chan-
nel(n).
TABLE 8: CONTENTS OF LLB(N) AND RLB(N) AND THE CORRESPONDING LOOP-BACK MODE FOR CHANNEL(N)
LLB(n)
RLB(n)
LOOP-BACK MODE (FOR CHANNEL(n))
0
0
None
1
0
Analog Loop-Back Mode (See Section 4.1 for Details)
1
1
Digital Loop-Back Mode (See Section 4.2 for Details
0
1
Remote Loop-Back Mode (See Section 4.3 for Details
5.3 OPERATING THE MICROPROCESSOR SERIAL
INTERFACE.
The XRT7302 Serial Interface is a simple four wire in-
terface that is compatible with many of the micro-con-
trollers available in the market. This interface con-
sists of the following signals:
CS - Chip Select (Active Low)
SClk - Serial Clock
SDI - Serial Data Input
SDO - Serial Data Output
Using the Microprocessor Serial Interface
The following instructions for using the Microproces-
sor Serial Interface are best understood by referring
to the diagram in Figure 31 and the timing diagram in
Figure 32.
In order to use the Microprocessor Serial Interface, a
clock signal must be first applied to the SClk input pin.
Then, initiate a Read or Write operation by asserting
the active-low Chip Select input pin CS. It is impor-
tant to assert the CS pin (e.g., toggle it “Low") at least
50ns prior to the very first rising edge of the clock sig-
nal.
Once the CS input pin has been asserted, the type of
operation and the target register address must now
be specified. Provide this information to the Micro-
processor Serial Interface by writing eight serial bits
of data into the SDI input.
NOTE: Each of these bits is clocked into the SDI input on
the rising edge of SClk.
Bit 1- R/W (Read/Write) Bit
This bit is clocked into the SDI input on the first rising
edge of SClk after CS has been asserted. This bit in-
dicates whether the current operation is a Read or
Write operation. A "1" in this bit specifies a Read op-
eration, a "0" in this bit specifies a Write operation.
Bits 2 through 5: The four (4) bit Address Values
(labeled A0, A1, A2 and A3)
The next four rising edges of the SClk signal clocks in
the 4-bit address value for this particular Read or
Write operation. The address selects the Command
Register in the XRT7302 that the user either be read-
ing data from or writing data to. The address bits
must be applied to the SDI input pin in ascending or-
der with the LSB (least significant bit) first.
Bit 6 and 7:
54
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