Texas Instruments XIO2213B Evaluation Module / Reference Design XIO2213BEVM XIO2213BEVM Datenbogen
Produktcode
XIO2213BEVM
SCPS210F – OCTOBER 2008 – REVISED MAY 2013
10
Physical Layer (PHY) Section
The cable interface can follow either the IEEE Std 1394a-2000 protocol or the IEEE Std 1394b-2002
protocol on all ports. The mode of operation is determined by the interface capabilities of the ports
being connected. When either of the ports is connected to an IEEE Std 1394a-2000-compliant device,
the cable interface on that port operates in the IEEE Std 1394a-2000 data-strobe mode at a compatible
S100, S200, or S400 speed. When a bilingual port is connected to an IEEE Std 1394b-2002-compliant
node, the cable interface on that port operates per the IEEE Std 1394b-2002 standard at S400B or
S800 speed. The XIO2213B automatically determines the correct cable interface connection method
for the bilingual ports.
protocol on all ports. The mode of operation is determined by the interface capabilities of the ports
being connected. When either of the ports is connected to an IEEE Std 1394a-2000-compliant device,
the cable interface on that port operates in the IEEE Std 1394a-2000 data-strobe mode at a compatible
S100, S200, or S400 speed. When a bilingual port is connected to an IEEE Std 1394b-2002-compliant
node, the cable interface on that port operates per the IEEE Std 1394b-2002 standard at S400B or
S800 speed. The XIO2213B automatically determines the correct cable interface connection method
for the bilingual ports.
To operate a port as an IEEE Std 1394b-2002 bilingual port, the data-strobe-only terminal for the port
(DS0, DS1, or DS2_P ) must be pulled to ground through a 1-k
(DS0, DS1, or DS2_P ) must be pulled to ground through a 1-k
Ω
resistor. The port must be operated in
the IEEE Std 1394b-2002 bilingual mode whenever an IEEE Std 1394b-2002 bilingual or an IEEE Std
1394b-2002 beta-only connector is connected to the port. To operate the port as an IEEE Std 1394a-
2000-only port, the data-strobe-only terminal (DS0, DS1, or DS2_P) must be pulled to 3.3-V V
1394b-2002 beta-only connector is connected to the port. To operate the port as an IEEE Std 1394a-
2000-only port, the data-strobe-only terminal (DS0, DS1, or DS2_P) must be pulled to 3.3-V V
CC
through a 1-k
Ω
resistor. The only time the port must be forced to the data-strobe-only mode is if the
port is connected to an IEEE Std 1394a-2000 connector [either 6 pin (recommended) or 4 pin]. This
mode is provided to ensure that IEEE Std 1394b-2002 signaling is never sent across an IEEE Std
1394a-2000 cable.
mode is provided to ensure that IEEE Std 1394b-2002 signaling is never sent across an IEEE Std
1394a-2000 cable.
During packet reception, the serial data bits are split into 2-, 4-, or 8-bit parallel streams by the PHY
section and sent to the link-layer controller (LLC) section. The received data is also transmitted
(repeated) on the other connected and active cable ports.
section and sent to the link-layer controller (LLC) section. The received data is also transmitted
(repeated) on the other connected and active cable ports.
Both the twisted pair A (TPA) and the twisted pair B (TPB) cable interfaces incorporate differential
comparators to monitor the line states during initialization and arbitration when connected to an IEEE
Std 1394a-2000-compliant device. The outputs of these comparators are used by the internal logic to
determine the arbitration status. The TPA channel monitors the incoming cable common-mode voltage.
The value of this common-mode voltage is used during IEEE Std 1394a-2000-mode arbitration and
sets the speed of the next packet transmission. In addition, the TPB channel monitors the incoming
cable common-mode voltage on the TPB pair for the presence of the remotely supplied twisted pair
bias (TPBIAS) voltage.
comparators to monitor the line states during initialization and arbitration when connected to an IEEE
Std 1394a-2000-compliant device. The outputs of these comparators are used by the internal logic to
determine the arbitration status. The TPA channel monitors the incoming cable common-mode voltage.
The value of this common-mode voltage is used during IEEE Std 1394a-2000-mode arbitration and
sets the speed of the next packet transmission. In addition, the TPB channel monitors the incoming
cable common-mode voltage on the TPB pair for the presence of the remotely supplied twisted pair
bias (TPBIAS) voltage.
When connected to an IEEE Std 1394a-2000-compliant node, the XIO2213B PHY section provides a
1.86-V nominal bias voltage at the TPBIAS terminal for port termination. The PHY section contains
three independent TPBIAS circuits (one for each port). This bias voltage, when seen through a cable
by a remote receiver, indicates the presence of an active connection. This bias voltage source must be
stabilized by an external filter capacitor of 1
1.86-V nominal bias voltage at the TPBIAS terminal for port termination. The PHY section contains
three independent TPBIAS circuits (one for each port). This bias voltage, when seen through a cable
by a remote receiver, indicates the presence of an active connection. This bias voltage source must be
stabilized by an external filter capacitor of 1
μ
F.
The line drivers in the XIO2213B PHY section are designed to work with external 112-
Ω
termination
resistor networks in order to match the 110-
Ω
cable impedance. One termination network is required at
each end of a twisted-pair cable. Each network is composed of a pair of series-connected 56-
Ω
resistors. The midpoint of the pair of resistors that is connected to the TPA terminals is connected to its
corresponding TPBIAS voltage terminal. The midpoint of the pair of resistors that is directly connected
to the TPB terminals is coupled to ground through a parallel RC network, with recommended values of
5 k and 270 pF. The values of the external line-termination resistors are selected to meet the standard
specifications when connected in parallel with the internal receiver circuits. A precision external resistor
connected between the R0 and R1 terminals sets the driver output current, along with other internal
operating currents.
corresponding TPBIAS voltage terminal. The midpoint of the pair of resistors that is directly connected
to the TPB terminals is coupled to ground through a parallel RC network, with recommended values of
5 k and 270 pF. The values of the external line-termination resistors are selected to meet the standard
specifications when connected in parallel with the internal receiver circuits. A precision external resistor
connected between the R0 and R1 terminals sets the driver output current, along with other internal
operating currents.
When the power supply of the XIO2213B is off while the twisted-pair cables are connected, the
XIO2213B transmitter and receiver circuitry present to the cable a high-impedance signal that does not
load the device at the other end of the cable.
XIO2213B transmitter and receiver circuitry present to the cable a high-impedance signal that does not
load the device at the other end of the cable.
Copyright © 2008–2013, Texas Instruments Incorporated
Physical Layer (PHY) Section
179
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