LAN8810 Datasheet, PDF (15/83 Pages) Microchip Technology – GMII 10/100/1000 Ethernet Transceiver

LAN8810/LAN8810I
TABLE 3-1: MASTER/SLAVE RESOLUTION FOR 1000BASE-T (CONTINUED)
Manual Master
Multi-Port
Master
Slave
Manual Master
Manual Master
No Link
No Link
Manual Master
Manual Slave
Manual Slave
Manual Slave
Single-Port
Multi-Port
Master
Slave
Slave
Slave
Master
Master
Manual Slave
Manual Master
Slave
Master
Manual Slave
Manual Slave
No Link
No Link
3.1.5 MANUAL OPERATION
The device supports a manual (forced) operation for test purposes. In manual operation, the user sets the link speed
(10Mbps or 100Mbps) and the duplex state (full or half).
Auto-negotiation must be disabled in order to manually configure the speed and the duplex. This may be accomplished
using the configuration pins, as described in Section 3.8.1.2.2, "Configuring the Mode of Operation (CONFIG[3:2])," on
page 26, or by using the Basic Control Register register as described in Section 3.1.2, "Disabling Auto-negotiation," on
page 14. For 10BASE-T and 100BASE-TX, the link state of the device is determined by the Speed Select[1], Speed
Select[0], and Duplex Mode bits of the Basic Control Register. Manual operation at a link speed of 1000Mbps is not
supported.
3.1.6 HALF VS. FULL-DUPLEX
Half-duplex operation relies on the CSMA/CD (Carrier Sense Multiple Access / Collision Detect) protocol to handle net-
work traffic and collisions. In this mode, the internal carrier sense signal, CRS, responds to both transmit and receive
activity. If data is received while the PHY is transmitting, a collision results.
In full-duplex mode, the PHY is able to transmit and receive data simultaneously and collision detection is disabled. In
this mode, the internal CRS responds only to receive activity. In 10BASE-T and 100BASE-T mode, CRS is redefined to
respond only to received activity. In 1000BASE-T, CRS is disabled.
Table 3-2 describes the behavior of the internal CRS bit under all receive/transmit conditions.
TABLE 3-2: CRS BEHAVIOR
Mode
Manual
Manual
Manual
Manual
Manual
Manual
Manual
Manual
Auto-Negotiation
Auto-Negotiation
Speed
10 Mbps
10 Mbps
10 Mbps
10 Mbps
100 Mbps
100 Mbps
100 Mbps
100 Mbps
10 Mbps
10 Mbps
Duplex
Half-Duplex
Half-Duplex
Full-Duplex
Full-Duplex
Half-Duplex
Half-Duplex
Full-Duplex
Full-Duplex
Half-Duplex
Half-Duplex
Activity
Transmitting
Receiving
Transmitting
Receiving
Transmitting
Receiving
Transmitting
Receiving
Transmitting
Receiving
CRS Behavior
(Note 3-1)
Active
Active
Low
Active
Active
Active
Low
Active
Active
Active
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DS00001870B-page 15