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LAN9218 参数 Datasheet PDF下载

LAN9218图片预览
型号: LAN9218
PDF下载: 下载PDF文件 查看货源
内容描述: 高性能单芯片10/100以太网控制器,带有HP Auto-MDIX的 [High-Performance Single- Chip 10/100 Ethernet Controller with HP Auto-MDIX]
分类和应用: 控制器以太网局域网(LAN)标准
文件页数/大小: 130 页 / 1558 K
品牌: SMSC [ SMSC CORPORATION ]
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High-Performance Single-Chip 10/100 Ethernet Controller with HP Auto-MDIX  
Datasheet  
Writing register 4 bits [8:5] allows software control of the capabilities advertised by the PHY. Writing  
register 4 does not automatically re-start auto-negotiation. Register 0, bit 9 must be set before the new  
abilities will be advertised. Auto-negotiation can also be disabled via software by clearing register 0,  
bit 12.  
The LAN9218 does not support “Next Page" capability.  
4.7  
Parallel Detection  
If the LAN9218 is connected to a device lacking the ability to auto-negotiate (i.e. no FLPs are  
detected), it is able to determine the speed of the link based on either 100M MLT-3 symbols or 10M  
Normal Link Pulses. In this case the link is presumed to be half-duplex per the IEEE standard. This  
ability is known as “Parallel Detection. This feature ensures inter operability with legacy link partners.  
If a link is formed via parallel detection, then bit 0 in register 6 is cleared to indicate that the Link  
Partner is not capable of auto-negotiation. The Ethernet MAC has access to this information via the  
management interface. If a fault occurs during parallel detection, bit 4 of register 6 is set.  
Register 5 is used to store the Link Partner Ability information, which is coded in the received FLPs.  
If the Link Partner is not auto-negotiation capable, then register 5 is updated after completion of parallel  
detection to reflect the speed capability of the Link Partner.  
4.7.1  
Re-starting Auto-negotiation  
Auto-negotiation can be re-started at any time by setting register 0, bit 9. Auto-negotiation will also re-  
start if the link is broken at any time. A broken link is caused by signal loss. This may occur because  
of a cable break, or because of an interruption in the signal transmitted by the Link Partner. Auto-  
negotiation resumes in an attempt to determine the new link configuration.  
If the management entity re-starts Auto-negotiation by writing to bit 9 of the control register, the  
LAN9218 will respond by stopping all transmission/receiving operations. Once the break_link_timer is  
done, in the Auto-negotiation state-machine (approximately 1200ms) the auto-negotiation will re-start.  
The Link Partner will have also dropped the link due to lack of a received signal, so it too will resume  
auto-negotiation.  
4.7.2  
4.7.3  
Disabling Auto-negotiation  
Auto-negotiation can be disabled by setting register 0, bit 12 to zero. The device will then force its  
speed of operation to reflect the information in register 0, bit 13 (speed) and register 0, bit 8 (duplex).  
The speed and duplex bits in register 0 should be ignored when auto-negotiation is enabled.  
Half vs. Full-Duplex  
Half-duplex operation relies on the CSMA/CD (Carrier Sense Multiple Access / Collision Detect)  
protocol to handle network traffic and collisions. In this mode, the carrier sense signal, CRS, responds  
to both transmit and receive activity. In this mode, 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. In this mode, CRS  
responds only to receive activity. The CSMA/CD protocol does not apply and collision detection is  
disabled.  
4.8  
HP Auto-MDIX  
HP Auto-MDIX facilitates the use of CAT-3 (10 Base-T) or CAT-5 (100 Base-T) media UTP interconnect  
cable without consideration of interface wiring scheme. If a user plugs in either a direct connect LAN  
cable, or a cross-over patch cable, as shown in Figure 4.3, the SMSC LAN9218 Auto-MDIX PHY is  
capable of configuring the TPO and TPI twisted pair pins for correct transceiver operation.  
SMSC LAN9218  
Revision 1.5 (07-18-06)  
DATA6S3HEET