20.3.11
Serial Management Interface
The Ethernet MAC has the ability to program the integrated PHY through internal serial MDIO and
MDC signals. The MDC signal is a 2.5 MHz clock that is sourced from system clock and then divided
down to the required frequency by programming the
CR
field in the
Ethernet MAC MII Address
(EMACMIIADDR)
register. To access the integrated PHY, the
PLA
field in the
EMACMIIADDR
register must be 0x0.
20.3.12
Interrupt Configuration
Interrupts can be generated from the MAC as a result of various events in the MAC and sub-modules.
MAC interrupts are enabled or disabled in the
Ethernet MAC Interrupt Mask (EMACIM)
register,
MAC offset 0x03C. Each interrupt event can be masked by setting the corresponding mask bit in
the
EMACIM
register.
The interrupt register bits in the
Ethernet MAC Raw Interrupt Status (EMACRIS)
register only
indicate the sub-module from which the event is reported. The application must read the
corresponding status registers to clear the interrupt.
20.4
Ethernet PHY
The integrated PHY supports 10Base-T and 100Base-TX signaling. It integrates all the physical-layer
functions needed to transmit and receive data on standard twisted-pair cables. The PHY directly
interfaces to the integrated Media Access Controller (MAC).
The Ethernet PHY uses mixed-signal processing to perform equalization, data recovery, and error
correction to achieve robust operation over CAT5 twisted-pair wiring. It not only meets the
requirements of IEEE 802.3, but maintains high margins in terms of alien cross-talk. The following
highlights the features of the PHY module:
■ Cable Diagnostics
■ Programmable Fast Link Down Modes
■ Auto-MDIX for 10/100Mbs
■ Energy Detection Mode
■ Serial Management Interface
■ IEEE 802.3u Auto-Negotiation and Parallel Detection
■ IEEE 802.3u ENDEC, 10Base-T Transceivers and Filters
■ IEEE 802.3u PCS, 100Base-TX Transceivers
■ Integrated ANSI X3.263 Compliant TP-PMD Physical Sublayer with Adaptive Equalization and
Baseline Wander Compensation
■ Three programmable LEDs that support detection of Link OK, 10/100Mbs activity, TX/RX transfers,
collisions and full duplex mode
20.4.1
Integrated PHY Block Diagram
The following figure shows the internal PHY integration. Note that the reference clock input comes
from an external 25 MHz ± 50 ppm crystal or oscillator connected to the MOSC signals.
1457
June 18, 2014
Texas Instruments-Production Data
Tiva
™
TM4C1294NCPDT Microcontroller