TAN-042
Designing the XRT71D00 and the XRT73L00 Devices to
operate in the Host Mode, and to be accessed via a single Chip
Select pin.
Preliminary
July 19, 2001
Revision 1.03
33
Bit D2 – TXCLKINV (Transmit Clock Invert)
This “Read/Write” bit-field permits the user to configure the Transmit Section of the LIU
IC to latch the contents of the “TPDATA/TNDATA” input pin upon either the rising or
falling edge of TXCLK.
Setting this bit-field to “0” configures the Transmit Section to latch the
TPDATA/TNDATA signal upon the falling edge of TXCLK. Conversely, setting this
bit-field to “1” configures the Transmit Section to latch the TPDATA/TNDATA signal
upon the rising edge of TXCLK.
Bit D3 – TAOS (Transmit All Ones)
This “Read/Write” bit-field permits the user to configure the Transmit Section of the LIU
IC to transmit an “All Ones” pattern onto the line.
Setting this bit-field to “1” configures the Transmit Section to transmit an “All Ones”
pattern onto the line. Setting this bit-field to “0” configures the Transmit Section to
transmit data based that which is sampled via the TPDATA/TNDATA input pins.
Bit D4 – TXOFF (Transmit Shut OFF)
This “Read-Write” bit-field permits the user to turn on or turn-off the Transmit Output
Driver of the XRT73L00 device.
When the user turns on the Transmit Output Driver of the XRT73L00, then the LIU will
generate and output a bipolar line signal (via the TTIP and TRING output pins), based
upon the data that it samples on the TPDATA/TNDATA input pin via the TCLK clock
signal. When the user turn off the Transmit Output Driver of the XRT73L00, then no
bipolar line signal will be output onto the line. Further, the TTIP and TRING output pins
will be “tri-stated”.
NOTE:
In contrast to most of the other hardware-mode external input pins, the state of
the “TxOFF” input pin is NOT ignored, whenever the XRT73L00 device is configured to
operate in the “HOST” Mode. Therefore, if the user wishes to control the “ON/OFF” of
the Transmit Output Driver, via the Microprocessor Serial Input; he/she must ensure that
the “TxOFF” input pin is tied to “GND”.