MC68160C Motorola, MC68160C Datasheet - Page 26

• Manufacturer Part Number: MC68160C
• Description: ENHANCED ETHERNET INTERFACE TRANSCEIVER
• Manufacturer: Motorola

has begun, the EEST is still transmitting, the TPJABB pin will
assert to signify a jabber condition. Also, the CLLED pin will
transition high and low alternately with a 100 ms period. The
transmit circuitry is, however, unaffected by the jabber
condition, so the communications controller has the
responsibility of monitoring and stopping transmission.
begin the end of transmit and decay to idle responses
necessary to meet requirements of the 802.3 standard for the
TP and AUI port.
Data Reception
reception to the RX pin of the EEST is initiated by signaling at
the RX+/– or AUI ARX+/– pins. If at the TP port, the data is
screened for validity by checking for sequence and pulse
width requirements, then passed to the decode and receive
circuitry. The RENA pin asserts and the data and
corresponding clock is passed to the communications
controller. After the frame has been transmitted, the
MC68160, B and C detects the ending transmission and
negates RENA. If at the AUI port, the data is checked for
proper pulse width requirements before being passed to the
decode circuitry. If the data pulses are longer than at least 20
ns, RENA gets asserted and the frame is decoded to RX with
and accompanying RCLK output.
Collision
activity by two or more stations on the network. In the event of
collision, the data transfer paths are unaffected. If the
MC68160, B and C is in the twisted pair mode, collision is
detect by simultaneous receive and transmit activity. If in the
AUI mode, collision is detected by activity on the ACX+/–
pins. In either case, if collision is detected, the CLSN pin will
assert to notify the communications controller.
Jabber
In the event that the transmitting station continues to transmit
beyond the allowable transmit time, a jabber timer (40 ms) will
expire and assert the TPJABB pin to alert the communications
26
If after approximately 40 ms after a TP or AUI transmission
When transmission is complete, the transmit circuitry will
Other than the case of being in Loop Back mode, data
Collision is the occurrence of simultaneous transmit
The EEST has a jabber timer to detect the jabber condition.
MC68160 MC68160B MC68160C
controller of the situation. The TPJABB pin can source or sink
up to 10 mA, and so, is capable of driving a status LED. In the
AUI mode, the pin is driven to high impedance since the
transceiver connected to the AUI port must alert the
communications controller of the jabber condition.
Full Duplex
Duplex mode. In this mode the EEST is capable of
transmitting and receiving simultaneously. Collision
conditions are not announced and internal loop back is
disabled. The remainder of the EEST functionality remains
unchanged from the non–Full Duplex mode. Full Duplex
mode is enabled by asserting the TPFULDL pin.
Auto Port Selection
automatically select the TP or AUI port depending on the
presence of valid link beats or frames at the TP RX+/– pins. If
the AUI port is automatically selected by another transmitting
station or by setting TPEN low, the TP transmit port of the
EEST continues to transmit link beats to keep the link active.
Auto Polarity Selection
MC68160, B and C has the ability to automatically reverse the
pins internally so that the received data is valid. In addition, an
open collector status pin (TPPLR) is driven low to indicate the
fault. In the AUI or reset mode this pin presents a high
impedance.
Loop Back Mode
the connected network, the EEST has a Loop Back mode.
Loop Back mode routes transmit data and clock to the
receive data and clock pins using as much of the transmit and
receive circuitry as possible. This gives a test of the
MC68160, B and C Manchester encode and decode function.
LOOP must not be asserted when TPFULDL pin is asserted.
This causes the MC68160, B and C to enter a test mode. This
test mode is used during final test and is not intended to be
entered under normal operation (see Application Notes
section).
If the APORT pin is asserted, the MC68160, B and C will
If the RX+ and the RX– wires happen to get reversed, the
To test the transmit and receive circuitry without disturbing
A feature unique to the MC68160, B and C is the Full
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