DP83620和TM4C129DNCPDT配合连接光纤以太网

板卡上ARM型号TM4C129DNCPDT，通过MII和DP83620连接，DP83620连接安华高SFP的HFBR57E5.

硬件原理图如附件。

现在的问题是，上电后ARM不烧写程序，只连接SFP的发送光纤到MOXA光电转化器的话，MOXA显示可以link。

可是如果我把SFP的接收光纤也连到MOXA光电转化器的话，MOXA就显示不能link，现在还不能找到原因，希望TI能够帮助分析下电路。

我感觉PHY在Fiber模式下能不能link和软件没关系，只和硬件有关。

Hi, 如果是FIBER mode，DP83820还是需要配置的，上电默认是双绞线mode。

The DP83620 supports both Twister Pair (100BASE-TX and 10BASE-T) and Fiber (100BASE-FX) media.
The port may be configured for Twisted Pair (TP) or Fiber (FX) operation by strap option or by register
access.
At power-up/reset, the state of the RX_ER pin will select the media for the port. The default selection is
twisted pair mode, while an external pull-down will select FX mode of operation. Strapping the port into FX
mode also automatically sets the Far-End Fault Enable, bit 3 of PCSR (16h), the Scramble Bypass, bit 1
of PCSR (16h) and the Descrambler Bypass, bit 0 of PCSR (16h). In addition, the media selection may be
controlled by writing to bit 6, FX_EN, of PCSR (16h).