交换机芯片8305NB的设计参考，原理图可以直接拿来用，网络稳压器和网口部分需要根据自己需要来修改。

KSZ8895交换机芯片，使用STM32F437芯片通过MII接口连接交换机芯片通信，使用SPI配置寄存器进行模式配置；也可纯硬件配置CONFIG0和CONFIG1进行配置，5口交换机亲测100M正常使用。

 RTL8370N-VB: Single-chip 8-port gigabit non-blocking switch architecture  Embedded 8-port 10/100/1000Base-T PHY  Each port supports full duplex 10/100/1000M connectivity (half duplex only supported in 10/100M mode)  Full-duplex and half-duplex operation with IEEE 802.3x flow control and backpressure  Supports 9216-byte jumbo packet length forwarding at wire speed  Supports Realtek Cable Test (RTCT) function  Supports 96-entry ACL Rules  Search keys support physical port, Layer2, Layer3, and Layer4 information  Actions support mirror, redirect, dropping, priority adjustment, traffic policing, CVLAN decision, and SVLAN assignment  Supports 5 types of user defined ACL rule format for 64 ACL rules  Optional per-port enable/disable of ACL function  Optional setting of per-port action to take when ACL mismatch  Supports IEEE 802.1Q VLAN  Supports 4K VLANs and 32 Extra Enhanced VLANs  Supports Un-tag definition in each VLAN  Supports VLAN policing and VLAN forwarding decision  Supports Port-based, Tag-based, and Protocol-based VLAN  Up to 4 Protocol-based VLAN entries  Supports per-port and per-VLAN egress VLAN tagging and un-tagging  Supports IVL, SVL, and IVL/SVL  Supports 4096-entry MAC address table with 4-way hash algorithm  Up to 4096 L2/L3 Filtering Database  Supports Spanning Tree port behavior configuration  IEEE 802.1w Rapid Spanning Tree  IEEE 802.1s Multiple Spanning Tree with up to 16 Spanning Tree instances  Supports IEEE 802.1x Access Control Protocol  Port-Based Access Control  MAC-Based Access Control  Guest VLAN  Supports Quality of Service (QoS)  Supports per port Input Bandwidth Control  Traffic classification based on IEEE 802.1p/Q priority definition, physical Port, IP DSCP field, ACL definition, VLAN based priority, MAC based priority, and SVLAN b