adm8515 Infineon Technologies Corporation, adm8515 Datasheet - Page 21

• Manufacturer Part Number: adm8515
• Description: Usb2.0 To 10/100 Mbit/s Ethernet Lan Controller Adm8515/x
• Manufacturer: Infineon Technologies Corporation

3
3.1
USB is a straightforward solution when you want to use a computer for communication with devices outside the
computer. The interface is suitable for one-of-kind and small-scale designs as well as mass-produced, standard
peripheral. The benefits of USB are easy to use and easy to apply, fast and reliable data transfers, flexibility, cost,
and power conservation.
3.1.1
PIE (Parallel Interface Engine) is to control USB communications and check USB protocol, then transfer protocol
to EP decoder. The PIE and USB transceivers, which provide the hardware interface to the USB cable, together
comprise the USB engine.
3.1.2
The detail description is in Section 4.5 USB Command.
3.2
3.2.1
The Media Independent Interface (MII) is an 18 wire MAC/PHY interface described in 802.3u. The purpose of the
interface is to allow MAC layer devices to attach to a variety of Physical Layer devices through a common
interface. MII operates at 100 Mbit/s or 10 Mbit/s, dependant on the speed of the Physical Layer. With clocks
running at either 25 MHz or 2.5 MHz, 4 bit data is clocked between the MAC and PHY, synchronous with Enable
and Error signals.
On receipt of valid data from the wire interface, RX_DV will go active signaling to the MAC that the valid data will
be presented on the RXD[3:0] pins at the speed of the RX_CLK.
On transmission of data from the MAC, TX_EN is presented to the PHY indicating the presence of valid data on
TXD[3:0]. TXD[3:0] are sampled by the PHY synchronous to TX_CLK during the time that TX_EN is valid.
3.2.2
The amplitude and phase distortion from a cable causes inter-symbol interference (ISI) which makes clock and
data recovery difficult. The adaptive equalizer is designed to closely match the inverse transfer function of the
twisted-pairs cable. The equalizer has the ability to change its equalizer frequency response according to the cable
length. The equalizer will tune itself automatically for any cable, compensating for the amplitude and phase
distortion introduced by the cable.
3.2.3
After the MAC transmitter exceeds the jabber timer, the transmit and loop back functions will be disabled and COL
signal gets asserted. After TX_EN goes low for more than 500 ms, the TP transmitter will reactivate and COL gets
de-asserted. Setting Jabber Disable will disable the jabber function.
When the SQE test is enabled, a COL pulse is asserted after each transmitted packet. SQE is enabled in
10Base-T by default.
Data Sheet
Function Description
USB Interface
PIE
EP Decoder
MAC Controller
MII
Adaptive Equalizer
Jabber and SQE
21
Function Description
Rev. 1.21, 2005-11-08
ADM8515/X