開發(fā)背景：
1、主芯片—STM32F207VCT6；
2、TCP/IP協(xié)議?！狶WIP，依托ST例程移植；
3、操作系統(tǒng)—無（裸機）；
異?，F(xiàn)象：
1、網(wǎng)線不插入的情況下先給設備上電，之后再插入網(wǎng)線無法ping通；（如果上電前網(wǎng)線插入，網(wǎng)絡正常）；
2、網(wǎng)絡已經(jīng)正常的情況下，電腦PC端修改傳輸模式（比如從原來的100M全雙工修改為10M全雙工）導致網(wǎng)絡不通；
原因分析：
1、針對第一種異常情況，是由于上電時網(wǎng)線未插入，導致ETH初始化部分未能成功完成，之后即使再插入網(wǎng)線，程序中沒有再次進行初始化的邏輯補充，從而導致網(wǎng)絡異常；
2、針對第二種情況，情況是上電時完成了ETH的初始化并與PC協(xié)商成功，此時網(wǎng)絡正常。但當PC端修改傳輸模式后，程序中未能執(zhí)行再次協(xié)商與MAC的初始化工作，導致網(wǎng)絡異常；
解決方法：
首先，要明確上述問題的關鍵點所在，所有的異常均是網(wǎng)線的拔插導致（PC端修改連接傳輸方式時也相當于網(wǎng)線的拔掉重插），因此主程序中必須要有對當前網(wǎng)絡連接與斷開的檢測或者利用PHY芯片的中斷引腳；
其次，無論利用輪詢或是PHY中斷配置引腳，根本的原理都是一樣的，就是感知到網(wǎng)絡的連接與斷開，下面給出采用的查詢方式：
void Eth_Link_ITHandler(struct netif *netif)
{
/* Check whether the link interrupt has occurred or not */
if(((ETH_ReadPHYRegister(DP83848_PHY_ADDRESS, PHY_MISR)) & PHY_LINK_STATUS) != 0){/*檢測插拔中斷*/
uint16_t status = ETH_ReadPHYRegister(DP83848_PHY_ADDRESS, PHY_BSR);
if(status & (PHY_AutoNego_Complete | PHY_Linked_Status)){/*檢測到網(wǎng)線連接*/
if(EthInitStatus == 0){/*之前未成功初始化過*/
/*Reinit PHY*/
ETH_Reinit();
}
else{/*之前已經(jīng)成功初始化*/
/*set link up for re link callbalk function*/
netif_set_link_up(netif);
}
}
else{/*網(wǎng)線斷開*/
/*set link down for re link callbalk function*/
netif_set_link_down(netif);
}
}
}
備注說明：將該檢測函數(shù)放入主循環(huán)，程序中標注的部分為解決網(wǎng)線熱拔插問題的關鍵點。
1、標注紅色的部分執(zhí)行的條件是檢測到網(wǎng)線插入且之前ETH部分未成功初始化過（即之前一直處在上電但網(wǎng)線未插入）的情況，此時需要對ETH重新初始化，從而解決異常現(xiàn)象的第一種情況，具體執(zhí)行內(nèi)容為：
/**
* @brief : first time power on but init failed, do again
* @param : None
*
* @retval : None
* @author : xuk
*/
void ETH_Reinit(void){
/* Configure Ethernet */
EthInitStatus =ETH_Init(Ð_InitStructure, DP83848_PHY_ADDRESS);
}
其中ETH_InitStructure已設為全局結(jié)構體；
2、標注藍色部分的執(zhí)行條件是已經(jīng)成功初始化過ETH，但之后出現(xiàn)了網(wǎng)線的拔插情況，此時需要在每次檢測到網(wǎng)絡連接時重新進行自協(xié)商并初始化MAC，具體的執(zhí)行流程如下介紹：
A、檢測到該條件時，首先調(diào)用：
netif_set_link_up(netif);
netif_set_link_down(netif);
B、追溯兩個函數(shù)的定義處，如下：
#if LWIP_NETIF_LINK_CALLBACK
/**
* Called by a driver when its link goes up
*/
void netif_set_link_up(struct netif *netif )
{
netif->flags |= NETIF_FLAG_LINK_UP;
#if LWIP_DHCP
if (netif->dhcp) {
dhcp_network_changed(netif);
}
#endif /* LWIP_DHCP */
#if LWIP_AUTOIP
if (netif->autoip) {
autoip_network_changed(netif);
}
#endif /* LWIP_AUTOIP */
if (netif->flags & NETIF_FLAG_UP) {
#if LWIP_ARP
/* For Ethernet network interfaces, we would like to send a "gratuitous ARP" */
if (netif->flags & NETIF_FLAG_ETHARP) {
etharp_gratuitous(netif);
}
#endif /* LWIP_ARP */
#if LWIP_IGMP
/* resend IGMP memberships */
if (netif->flags & NETIF_FLAG_IGMP) {
igmp_report_groups( netif);
}
#endif /* LWIP_IGMP */
}
NETIF_LINK_CALLBACK(netif);
}
/**
* Called by a driver when its link goes down
*/
void netif_set_link_down(struct netif *netif )
{
netif->flags &= ~NETIF_FLAG_LINK_UP;
NETIF_LINK_CALLBACK(netif);
}
/**
* Ask if a link is up
*/
u8_t netif_is_link_up(struct netif *netif)
{
return (netif->flags & NETIF_FLAG_LINK_UP) ? 1 : 0;
}
/**
* Set callback to be called when link is brought up/down
*/
voidnetif_set_link_callback(struct netif *netif, void (* link_callback)(struct netif *netif ))
{
if (netif) {
netif->link_callback = link_callback;
}
}
#endif /* LWIP_NETIF_LINK_CALLBACK */
注意：I：從上述看出，若要這兩個函數(shù)有效編譯，則必須定義宏LWIP_NETIF_LINK_CALLBACK 為1，請自行設置；
II：函數(shù)netif_set_link_callback的作用是指定網(wǎng)絡連接發(fā)生改變時的回調(diào)函數(shù)；
III：詳細的講一下主要思路，Eth_Link_ITHandler執(zhí)行中檢測到網(wǎng)線拔插時分別調(diào)用netif_set_link_up(netif)、netif_set_link_down(netif);這兩個函數(shù)的調(diào)用會引發(fā)netif_set_link_callback的執(zhí)行，從而執(zhí)行指定的網(wǎng)絡連接或斷開的回調(diào)函數(shù)；
Ⅳ：通過netif_set_link_callback該函數(shù)在LWIP初始化的時候指定網(wǎng)絡連接變化的回調(diào)函數(shù)，可放置如下位置：
void LwIP_Init(void){
......
......
......
......
/*set the link up or link down callback function - xuk*/
netif_set_link_callback(&netif,eth_re_link);
}
其中，回調(diào)函數(shù)eth_re_link的具體內(nèi)容如下，實現(xiàn)網(wǎng)絡拔插后的重新自協(xié)商與MAC初始化：
/**
* @brief : process the relink of eth
* @param : netif - - specify the ETH netif
*
* @retval : none
* @author : xuk
*/
voideth_re_link(struct netif *netif){
__IO uint32_t tickstart = 0;
uint32_t regvalue = 0, tmpreg = 0;
if(netif_is_link_up(netif)){/*link up process*/
if(ETH_InitStructure.ETH_AutoNegotiation == ETH_AutoNegotiation_Enable){/*AutoNegotiation_Enable*/
/* Enable Auto-Negotiation */
ETH_WritePHYRegister(DP83848_PHY_ADDRESS, PHY_BCR, PHY_AutoNegotiation);
/* Wait until the auto-negotiation will be completed */
do
{
tickstart++;
} while (!(ETH_ReadPHYRegister(DP83848_PHY_ADDRESS, PHY_BSR) & PHY_AutoNego_Complete) && (tickstart < (uint32_t)PHY_READ_TO));
/* Return ERROR in case of timeout */
if(tickstart == PHY_READ_TO)
{
// return ETH_ERROR;
}
/* Reset Timeout counter */
tickstart = 0;
/* Read the result of the auto-negotiation */
regvalue = ETH_ReadPHYRegister(DP83848_PHY_ADDRESS, PHY_SR);
/* Configure the MAC with the Duplex Mode fixed by the auto-negotiation process */
if((regvalue & PHY_DUPLEX_STATUS) != (uint32_t)RESET)
{
/* Set Ethernet duplex mode to Full-duplex following the auto-negotiation */
ETH_InitStructure.ETH_Mode = ETH_Mode_FullDuplex;
}
else
{
/* Set Ethernet duplex mode to Half-duplex following the auto-negotiation */
ETH_InitStructure.ETH_Mode = ETH_Mode_HalfDuplex;
}
/* Configure the MAC with the speed fixed by the auto-negotiation process */
if(regvalue & PHY_SPEED_STATUS)
{
/* Set Ethernet speed to 10M following the auto-negotiation */
ETH_InitStructure.ETH_Speed = ETH_Speed_10M;
}
else
{
/* Set Ethernet speed to 100M following the auto-negotiation */
ETH_InitStructure.ETH_Speed = ETH_Speed_100M;
}
}
else{/*AutoNegotiation_Disable*/
if(!ETH_WritePHYRegister(DP83848_PHY_ADDRESS, PHY_BCR, ((uint16_t)(ETH_InitStructure.ETH_Mode >> 3) |
(uint16_t)(ETH_InitStructure.ETH_Speed >> 1))))
{
/* Return ERROR in case of write timeout */
// return ETH_ERROR;
}
/* Delay to assure PHY configuration */
// _eth_delay_(PHY_CONFIG_DELAY);
}
/*------------------------ ETHERNET MACCR Configuration --------------------*/
/* Get the ETHERNET MACCR value */
tmpreg = ETH->MACCR;
/* Clear WD, PCE, PS, TE and RE bits */
tmpreg &= MACCR_CLEAR_MASK;
/* Set the WD bit according to ETH_Watchdog value */
/* Set the JD: bit according to ETH_Jabber value */
/* Set the IFG bit according to ETH_InterFrameGap value */
/* Set the DCRS bit according to ETH_CarrierSense value */
/* Set the FES bit according to ETH_Speed value */
/* Set the DO bit according to ETH_ReceiveOwn value */
/* Set the LM bit according to ETH_LoopbackMode value */
/* Set the DM bit according to ETH_Mode value */
/* Set the IPCO bit according to ETH_ChecksumOffload value */
/* Set the DR bit according to ETH_RetryTransmission value */
/* Set the ACS bit according to ETH_AutomaticPadCRCStrip value */
/* Set the BL bit according to ETH_BackOffLimit value */
/* Set the DC bit according to ETH_DeferralCheck value */
tmpreg |= (uint32_t)(ETH_InitStructure.ETH_Watchdog |
ETH_InitStructure.ETH_Jabber |
ETH_InitStructure.ETH_InterFrameGap |
ETH_InitStructure.ETH_CarrierSense |
ETH_InitStructure.ETH_Speed |
ETH_InitStructure.ETH_ReceiveOwn |
ETH_InitStructure.ETH_LoopbackMode |
ETH_InitStructure.ETH_Mode |
ETH_InitStructure.ETH_ChecksumOffload |
ETH_InitStructure.ETH_RetryTransmission |
ETH_InitStructure.ETH_AutomaticPadCRCStrip |
ETH_InitStructure.ETH_BackOffLimit |
ETH_InitStructure.ETH_DeferralCheck);
/* Write to ETHERNET MACCR */
ETH->MACCR = (uint32_t)tmpreg;
/*----------------------- ETHERNET MACFFR Configuration --------------------*/
/* Set the RA bit according to ETH_ReceiveAll value */
/* Set the SAF and SAIF bits according to ETH_SourceAddrFilter value */
/* Set the PCF bit according to ETH_PassControlFrames value */
/* Set the DBF bit according to ETH_BroadcastFramesReception value */
/* Set the DAIF bit according to ETH_DestinationAddrFilter value */
/* Set the PR bit according to ETH_PromiscuousMode value */
/* Set the PM, HMC and HPF bits according to ETH_MulticastFramesFilter value */
/* Set the HUC and HPF bits according to ETH_UnicastFramesFilter value */
/* Write to ETHERNET MACFFR */
ETH->MACFFR = (uint32_t)(ETH_InitStructure.ETH_ReceiveAll |
ETH_InitStructure.ETH_SourceAddrFilter |
ETH_InitStructure.ETH_PassControlFrames |
ETH_InitStructure.ETH_BroadcastFramesReception |
ETH_InitStructure.ETH_DestinationAddrFilter |
ETH_InitStructure.ETH_PromiscuousMode |
ETH_InitStructure.ETH_MulticastFramesFilter |
ETH_InitStructure.ETH_UnicastFramesFilter);
/*--------------- ETHERNET MACHTHR and MACHTLR Configuration ---------------*/
/* Write to ETHERNET MACHTHR */
ETH->MACHTHR = (uint32_t)ETH_InitStructure.ETH_HashTableHigh;
/* Write to ETHERNET MACHTLR */
ETH->MACHTLR = (uint32_t)ETH_InitStructure.ETH_HashTableLow;
/*-----------------------
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