mc68160a Freescale Semiconductor, Inc, mc68160a Datasheet - Page 25

• Manufacturer Part Number: mc68160a
• Description: Enhanced Ethernet Interface Circuit
• Manufacturer: Freescale Semiconductor, Inc

Introduction
connection to the Ethernet media. This is done through two
separate media dependent interfaces and a SIA interface.
The media dependent interfaces are the Attachment Unit
Interface(AUI) and the 10BASE–T Twisted Pair(TP) port. The
MC68160A’s SIA interface is compatible with most industry
controllers and selected by three mode control pins. Chip
status is supported indicated by the condition of 6 status
indicator pins. All but one are open collector outputs.
transmission. NRZ data from the communications controller
SIA interface is encoded by the MC68160A into Manchester
Code in preparation for transmission on the media. The data
is then applied to either the AUI or TP port. If the data was
transmitted using the 10BASE–T port, this data is also
looped back to the receive data interface SIA pins
connected to the controller. This allows detection of a
collision condition in the event that another station on the
media attempted transmission at the same time. After the
entire data frame has been transmitted, the EEST must
force the media idle signal. The idle signal frees the media
for other stations that have deferred transmission. If no
other transmissions are required the link enters an idle
state. During this idle state the 10BASE–T transmitter
issues idle pulses which communicates to the receiver
connected to the other side that the link is valid. If the
Input Voltage
The MC68160A was designed to perform the physical
If the EEST isn’t receiving data, the controller may initiate
Differential
–300mV
RENA/CLSN
ARX+/–/
ACX+/–
OROLA ANALOG IC DEVICE DATA
RCLK
RX
t 261
–40mV
Bit Q
t 266
–275mV
1
1.5V
Bit U
Freescale Semiconductor, Inc.
0
For More Information On This Pro
Bit Q
Bit V
1
FUNCTIONAL DESCRIPTION
Go to: www.freescale.com
Figure 40. ARX/ACX Timing
Bit U
Bit W
0
t 260
MC68160A
10%
90%
Bit V
Bit X
0
Bit U
transmitter connected at the other end begins transmission,
the EEST will assert a receive enable signal, and forward
the received data to the controller.
screened for proper sequence and pulse width requirements.
If the preamble of the received frame meets the
requirements, the PLL locks onto the 64–bit preamble and
begins to decode the Manchester Code to NRZ code. This
code is then presented to the communications controller at
the receive data pins at the SIA interface. If data is received
at the AUI port, it is sent directly to the communications
controller via the SIA interface.
Data Transmission
munications controller must be synchronized to TCLK.
Transmission to the 10BASE–T or AUI media occurs when
TENA is asserted and data is applied to the TX pin. Finally, to
signify transmission, the TXLED in will cycle on and off at a
100 ms period. Data transmission for EEST is accomplished
either over the 10BASE–T port or the AUI port. Both
connections to the media are made with industry standard
media interface components. The 10BASE–T interface
requires a filter and transformer, the AUI interface requires
only a transformer. The filter for the 10BASE–T transmit
circuit will have to be chosen for each application.
Bit Y
Upon reception of data at the 10BASE–T port, the data is
To have properly encoded transmit data, the com–
10%
90%
1
t 260
Bit X
0V
Bit Z
1
Bit Y
t 267
Bit Z
+300mV
1.5V
25