由RX0－RX3和CSR这几个脚组成PHYADDR0－4\n芯片复位时，会锁存这5个脚的电平，作为芯片地址，以后就找这个作访问了。\n所以，如果你是悬空的话，认为是0，一定要接1才认为是1.\n\n\n DP83848的地址由PHYAD[4:0]（总共是32个地址）决定，具体怎么决定请看芯片手册。当对PHY进行读操作发现读出的值都是0xffff时，如果硬件没问题，那就可以看一下是不是PHY的地址弄错了。一个简单的办法就是对0-31地址进行轮训，看哪个地址能读出正确的值。\n\n\n Table 6-5 PHY Address Mapping\n PIN # PHYAD FUNCTION RXD FUNCTION\n 35 ? ?PHYAD0 ? ?COL ? ?\n 36 ? ?PHYAD1 ? ?RXD_0 ? ?\n 37 ? ?PHYAD2 ? ?RXD_1 ? ?\n 38 ? ?PHYAD3 ? ?RXD_2 ? ?\n 39 ? ?PHYAD4 ? ?RXD_3 ? ?\n The DP83848x can be set to respond to any of 32 possible PHY addresses through strap pins. The information is latched into the PHYCR register (address 19h, bits [4:0]) at device power up and hardware reset. The PHY Address pins are shared with the RXD and COL pins. Each DP83848x or port sharing an MDIO bus in a system must he a unique physical address.\n\n\n来源:\nhttp://www.ti.com.cn/product/cn/DP83848T/datasheet/detailed_description.html\nhttp://blog.sina.com.cn/s/blog_64e5f47b0101fa8b.html\nhttp://www.amobbs.com/thread-5149652-1-1.html