由於專案需要，由STM32F107更換到了GD32F107，傳說中，完全PIN2PIN，程式碼基本不用改，這也是吸引人的地方。於是。。。。。

但是移植到ETH的時候，發現跑不通，資料只進不出，後面發現是DMA傳送不了資料。可是，為什麼DMA會發送不了？於是，就不是簡單的移植了，只能從最基本的下手了，資料怎麼進來？資料怎麼處理？資料怎麼出去？然後利用Wireshark抓包工具來，用STM32F107的舊板，抓取了上電之後，Lwip首先需要發出的資料是一個ARP請求包。GD32F107這個包怎麼都發不出去，後來無意在百度的時候看到一段配置程式碼，COPY下來放到我的程式碼裡，一執行，竟然發出去了，然後細細對比一番，原來是GD32F107不能採用自動協商模式。選定了100M模式後，一切正常，真是折騰死人，三天，整整折騰了三天。GD的工程師如果看到這文章，希望能給出解決辦法，或者如果讀者在自動協商下能正常執行的，歡迎指教指教。下面，我貼出配置程式碼。

/*------------------------   MAC   -----------------------------------*/
//ETH_InitStruct.ETH_AutoNegotiation = ETH_AutoNegotiation_Enable  ;
ETH_InitStruct.ETH_AutoNegotiation = ETH_AutoNegotiation_Disable;
ETH_InitStruct.ETH_Mode = ETH_Mode_FullDuplex;
ETH_InitStruct.ETH_Speed = ETH_Speed_100M;
ETH_InitStruct.ETH_LoopbackMode = ETH_LoopbackMode_Disable;
ETH_InitStruct.ETH_RetryTransmission = ETH_RetryTransmission_Disable;
ETH_InitStruct.ETH_AutomaticPadCRCStrip = ETH_AutomaticPadCRCStrip_Disable;
ETH_InitStruct.ETH_ReceiveAll = ETH_ReceiveAll_Disable;
ETH_InitStruct.ETH_BroadcastFramesReception = ETH_BroadcastFramesReception_Enable;
ETH_InitStruct.ETH_PromiscuousMode = ETH_PromiscuousMode_Disable;
ETH_InitStruct.ETH_MulticastFramesFilter = ETH_MulticastFramesFilter_Perfect;
ETH_InitStruct.ETH_UnicastFramesFilter = ETH_UnicastFramesFilter_Perfect;
#ifdef CHECKSUM_GEN_ICMP
ETH_InitStruct.ETH_ChecksumOffload = ETH_ChecksumOffload_Enable;
#endif


/*------------------------   DMA   -----------------------------------*/  
  
/* When we use the Checksum offload feature, we need to enable the Store and Forward mode: 
the store and forward guarantee that a whole frame is stored in the FIFO, so the MAC can insert/verify the checksum, 
if the checksum is OK the DMA can handle the frame otherwise the frame is dropped */
ETH_InitStruct.ETH_DropTCPIPChecksumErrorFrame = ETH_DropTCPIPChecksumErrorFrame_Enable; 
ETH_InitStruct.ETH_ReceiveStoreForward = ETH_ReceiveStoreForward_Enable;         
ETH_InitStruct.ETH_TransmitStoreForward = ETH_TransmitStoreForward_Enable;     


ETH_InitStruct.ETH_ForwardErrorFrames = ETH_ForwardErrorFrames_Disable;       
ETH_InitStruct.ETH_ForwardUndersizedGoodFrames = ETH_ForwardUndersizedGoodFrames_Disable;   
ETH_InitStruct.ETH_SecondFrameOperate = ETH_SecondFrameOperate_Enable;                                                          
ETH_InitStruct.ETH_AddressAlignedBeats = ETH_AddressAlignedBeats_Enable;      
ETH_InitStruct.ETH_FixedBurst = ETH_FixedBurst_Enable;                
ETH_InitStruct.ETH_RxDMABurstLength = ETH_RxDMABurstLength_32Beat;          
ETH_InitStruct.ETH_TxDMABurstLength = ETH_TxDMABurstLength_32Beat;                                                                 
ETH_InitStruct.ETH_DMAArbitration = ETH_DMAArbitration_RoundRobin_RxTx_2_1;