LPC1768以太網控制器
本文記錄LPC1768的以太網控制器學習使用心得。網卡芯片以DP83848C爲例。主芯片內的以太網控制器（EMAC）位於ISO模型中的數據鏈路層，而外圍網卡（PHY）位於ISO模型中的物理層。這兩者通過RMII（簡化的媒體獨立接口）連接這樣就可以一個簡單的以太網通信了。下面通過分析函數來了解相應的知識。分析LPC1768的例程。
<一>、控制器初始化函數。
Status EMAC_Init(EMAC_CFG_Type *EMAC_ConfigStruct)
{
/* Initialize the EMAC Ethernet controller. */
int32_t regv,tout, tmp;
/* Set up clock and power for Ethernet module */
CLKPWR_ConfigPPWR (CLKPWR_PCONP_PCENET, ENABLE);//(1)打開以太網控制器
/* Reset all EMAC internal modules */
LPC_EMAC->MAC1 = EMAC_MAC1_RES_TX | EMAC_MAC1_RES_MCS_TX | EMAC_MAC1_RES_RX |
EMAC_MAC1_RES_MCS_RX | EMAC_MAC1_SIM_RES | EMAC_MAC1_SOFT_RES;//(2)置位MAC1配置寄存器中的一些位。
LPC_EMAC->Command = EMAC_CR_REG_RES | EMAC_CR_TX_RES | EMAC_CR_RX_RES | EMAC_CR_PASS_RUNT_FRM;//(3)復位控制命令寄存器
/* A short delay after reset. */
for (tout = 100; tout; tout--);
/* Initialize MAC control registers. */
LPC_EMAC->MAC1 = EMAC_MAC1_PASS_ALL;//允許所有的幀信息傳送，包括常規幀和控制幀，使能接收功能時生效
LPC_EMAC->MAC2 = EMAC_MAC2_CRC_EN | EMAC_MAC2_PAD_EN;//允許填充短幀，添加CRC
LPC_EMAC->MAXF = EMAC_ETH_MAX_FLEN;//幀最大長度爲1536
/*
* Find the clock that close to desired target clock
*/
tmp = SystemCoreClock / EMAC_MCFG_MII_MAXCLK;
for (tout = 0; tout < sizeof (EMAC_clkdiv); tout++){
if (EMAC_clkdiv[tout] >= tmp) break;
}
tout++;
// Write to MAC configuration register and reset
LPC_EMAC->MCFG = EMAC_MCFG_CLK_SEL(tout) | EMAC_MCFG_RES_MII; //設置MII的AHB總線時鐘分頻數，復位MII
// release reset
LPC_EMAC->MCFG &= ~(EMAC_MCFG_RES_MII);//釋放MII復位
LPC_EMAC->CLRT = EMAC_CLRT_DEF;//
設置衝突後重發次數和衝突時間槽
LPC_EMAC->IPGR = EMAC_IPGR_P2_DEF;//設置非連續包時間間隔
/* Enable Reduced MII interface. */
LPC_EMAC->Command = EMAC_CR_RMII | EMAC_CR_PASS_RUNT_FRM;//將MAC設置爲RMII模式並設置可接收短幀
/* Reset Reduced MII Logic. */
LPC_EMAC->SUPP = EMAC_SUPP_RES_RMII; //未定義?
for (tout = 100; tout; tout--);
LPC_EMAC->SUPP = 0;//PHY支持寄存器,操作速率將爲10M(10/100M)
/* Put the DP83848C in reset mode */
write_PHY (EMAC_PHY_REG_BMCR, EMAC_PHY_BMCR_RESET);//（4）
/* Wait for hardware reset to end. */
for (tout = EMAC_PHY_RESP_TOUT; tout; tout--) {
regv = read_PHY (EMAC_PHY_REG_BMCR);
if (!(regv & (EMAC_PHY_BMCR_RESET | EMAC_PHY_BMCR_POWERDOWN))) {
/* Reset complete, device not Power Down. */
break;
}
if (tout == 0){
// Time out, return ERROR
return (ERROR);
}
}
// Set PHY mode
if (EMAC_SetPHYMode(EMAC_ConfigStruct->Mode) < 0){//(5)設置PHY模式，mode爲自動模式
return (ERROR);
}
// Set EMAC address
setEmacAddr(EMAC_ConfigStruct->pbEMAC_Addr);//設置MAC地址
/* Initialize Tx and Rx DMA Descriptors */
rx_descr_init ();//(6)
tx_descr_init ();//發射通道初始化，同理6
// Set Receive Filter register: enable broadcast and multicast
LPC_EMAC->RxFilterCtrl = EMAC_RFC_MCAST_EN | EMAC_RFC_BCAST_EN | EMAC_RFC_PERFECT_EN;
//RxFilterCtrl接收過濾控制寄存器，接收多播幀，接收廣播幀，接收和MAC地址相同的幀
/* Enable Rx Done and Tx Done interrupt for EMAC */
LPC_EMAC->IntEnable = EMAC_INT_RX_DONE | EMAC_INT_TX_DONE;//使能接收中斷和發送中斷
/* Reset all interrupts */
LPC_EMAC->IntClear = 0xFFFF;//清除中斷
/* Enable receive and transmit mode of MAC Ethernet core */
LPC_EMAC->Command |= (EMAC_CR_RX_EN | EMAC_CR_TX_EN);//接收使能，發送使能
LPC_EMAC->MAC1 |= EMAC_MAC1_REC_EN;//MAC寄存器中接收使能
return SUCCESS;
}
(1)CLKPWR_ConfigPPWR函數將設置外設功率控制寄存器（PCONP），以打開或者關閉相應的外設的時鐘源。
(2)復位的這些位定義如下，
#define EMAC_MAC1_RES_TX 0x00000100 /**< Reset TX Logic該位置位將使發送功能邏輯進入復位狀態*/
#define EMAC_MAC1_RES_MCS_TX 0x00000200 /**< Reset MAC TX Control Sublayer，MAC層的發送邏輯復位MCS執行流控制*/
#define EMAC_MAC1_RES_RX 0x00000400 /**< Reset RX Logic該位置位將使接受功能邏輯進入復位狀態*/
#define EMAC_MAC1_RES_MCS_RX 0x00000800 /**< Reset MAC RX Control Sublayer，MAC層的接受邏輯復位MCS執行流控制*/
#define EMAC_MAC1_SIM_RES 0x00004000 /**< Simulation Reset發送功能中的隨機數發生器復位*/
#define EMAC_MAC1_SOFT_RES 0x00008000 /**< Soft Reset MAC 將使MAC中的除主機接口的所有狀態復位*/
(3)定義如下
#define EMAC_CR_REG_RES 0x00000008
/**< Reset Host Registers 所有的通道和和主機寄存器都復位*/
#define EMAC_CR_TX_RES 0x00000010
/**< Reset Transmit Datapath 復位發送通道 */
#define EMAC_CR_RX_RES 0x00000020
/**< Reset Receive Datapath 復位接收通道*/
#define EMAC_CR_PASS_RUNT_FRM 0x00000040
/**< Pass Runt Frames 接收短幀功能 */
(4)這個函數是寫數據到外部網卡（PHY）的。
static int32_t write_PHY (uint32_t PhyReg, uint16_t Value)//PhyReg，PHY中寄存器地址 value，值
{
/* Write a data 'Value' to PHY register 'PhyReg'. */
uint32_t tout;
LPC_EMAC->MADR = EMAC_DEF_ADR | PhyReg;//EMAC_DEF_ADR是默認的PHY(最多可控制32個PHY)。MADR裏包含哪個PHY哪個寄存器
LPC_EMAC->MWTD = Value;//寄存器的值
/* Wait until operation completed */
tout = 0;
for (tout = 0; tout < EMAC_MII_WR_TOUT; tout++) {//等待操作結束
if ((LPC_EMAC->MIND & EMAC_MIND_BUSY) == 0) {
return (0);
}
}
// Time out!
return (-1);
}
(5)
int32_t EMAC_SetPHYMode(uint32_t ulPHYMode)
{
int32_t id1, id2, tout, regv;
/* Check if this is a DP83848C PHY. */
id1 = read_PHY (EMAC_PHY_REG_IDR1);//讀出PHY芯片的ID
id2 = read_PHY (EMAC_PHY_REG_IDR2);
#ifdef MCB_LPC_1768
if (((id1 << 16) | (id2 & 0xFFF0)) == EMAC_DP83848C_ID) {//ID是DP8384的ID
switch(ulPHYMode){//根據參數進入相應的部分設置PHY
case EMAC_MODE_AUTO:
write_PHY (EMAC_PHY_REG_BMCR, EMAC_PHY_AUTO_NEG);//設置PHY的Base Control寄存器的位爲自動選擇傳輸速率和方式
#elif defined(IAR_LPC_1768) /* Use IAR LPC1768 KickStart board */
if (((id1 << 16) | id2) == EMAC_KSZ8721BL_ID) {
/* Configure the PHY device */
switch(ulPHYMode){
case EMAC_MODE_AUTO:
/* Use auto-negotiation about the link speed. */
write_PHY (EMAC_PHY_REG_BMCR, EMAC_PHY_AUTO_NEG);
// write_PHY (EMAC_PHY_REG_BMCR, EMAC_PHY_BMCR_AN);
#endif
/* Wait to complete Auto_Negotiation */
for (tout = EMAC_PHY_RESP_TOUT; tout; tout--) {
regv = read_PHY (EMAC_PHY_REG_BMSR);
if (regv & EMAC_PHY_BMSR_AUTO_DONE) {
/* Auto-negotiation Complete. */
break;
}
if (tout == 0){
// Time out, return error
return (-1);
}
}
break;
case EMAC_MODE_10M_FULL:
/* Connect at 10MBit full-duplex */
write_PHY (EMAC_PHY_REG_BMCR, EMAC_PHY_FULLD_10M);
break;
case EMAC_MODE_10M_HALF:
/* Connect at 10MBit half-duplex */
write_PHY (EMAC_PHY_REG_BMCR, EMAC_PHY_HALFD_10M);
break;
case EMAC_MODE_100M_FULL:
/* Connect at 100MBit full-duplex */
write_PHY (EMAC_PHY_REG_BMCR, EMAC_PHY_FULLD_100M);
break;
case EMAC_MODE_100M_HALF:
/* Connect at 100MBit half-duplex */
write_PHY (EMAC_PHY_REG_BMCR, EMAC_PHY_HALFD_100M);
break;
default:
// un-supported
return (-1);
}
}
// It's not correct module ID
else {
return (-1);
}
// Update EMAC configuration with current PHY status
if (EMAC_UpdatePHYStatus() < 0){//這個函數會讀取PHY中的0x10寄存器來查出現在PHY的速率和傳輸方式，來設置MAC的速率和傳輸方式
return (-1);
}
// Complete
return (0);
}
(6)
static void rx_descr_init (void)
{
/* Initialize Receive Descriptor and Status array. */
uint32_t i;
for (i = 0; i < EMAC_NUM_RX_FRAG; i++) {
Rx_Desc[i].Packet = (uint32_t)&rx_buf[i];//<1>
Rx_Desc[i].Ctrl = EMAC_RCTRL_INT | (EMAC_ETH_MAX_FLEN - 1);//控制字段
Rx_Stat[i].Info = 0;
Rx_Stat[i].HashCRC = 0;
}
/* Set EMAC Receive Descriptor Registers. */
LPC_EMAC->RxDescriptor = (uint32_t)&Rx_Desc[0];//RxDescriptor保存接收描述符數組的基地址(最低地址)
LPC_EMAC->RxStatus = (uint32_t)&Rx_Stat[0]; //RxStatus
LPC_EMAC->RxDescriptorNumber = EMAC_NUM_RX_FRAG - 1;//接收描述符數目寄存器
/* Rx Descriptors Point to 0 */
LPC_EMAC->RxConsumeIndex = 0;//接收消耗索引，它與RxProductIndex(接收生產索引)組成環狀緩存形式
}
<1>rx_buf是一個二維數組，4個接收數據數組，每個1536字節
如：static uint32_t rx_buf[EMAC_NUM_RX_FRAG][EMAC_ETH_MAX_FLEN>>2];
小結總結：EMAC_Init函數初始化了了以太網模塊中的各個寄存器並通過其設置了外部的PHY，爲收發數據做好了準備。
<二>
之後程序打開了設置了各個變量後，調用函數
void DoNetworkStuff(void)
{
if (CheckFrameReceived()) // 函數將檢查RxConsumeIndex和RxProductIndex是否相等來判斷是否有數據來
{
if (IsBroadcast()) { //（1）
ProcessEthBroadcastFrame(); //廣播消息的處理
} else {
ProcessEthIAFrame(); //處理ARP幀和IP幀，本文不深入協議部分。
}
EndReadFrame(); //設置消耗索引RxConsumeIndex，即++，若索引到盡頭，因爲是環形緩衝，所以索引置0
}
if (TCPFlags & TCP_TIMER_RUNNING)
if (TCPFlags & TIMER_TYPE_RETRY)
{
if (TCPTimer > RETRY_TIMEOUT)
{
TCPRestartTimer(); // set a new timeout
if (RetryCounter)
{
TCPHandleRetransmission(); // resend last frame
RetryCounter--;
}
else
{
TCPStopTimer();
TCPHandleTimeout();
}
}
}
else if (TCPTimer > FIN_TIMEOUT)
{
TCPStateMachine = CLOSED;
TCPFlags = 0; // reset all flags, stop retransmission...
SocketStatus &= SOCK_DATA_AVAILABLE; // clear all flags but data available
}
switch (TCPStateMachine)
{
case CLOSED :
case LISTENING :
{
if (TCPFlags & TCP_ACTIVE_OPEN) // stack has to open a connection?
if (TCPFlags & IP_ADDR_RESOLVED) // IP resolved?
if (!(TransmitControl & SEND_FRAME2)) // buffer free?
{
TCPSeqNr = ((unsigned long)ISNGenHigh << 16) | (SysTick->VAL & 0xFFFF); // NXP: changed from T0TC to SysTick->VAL;
// set local ISN
TCPUNASeqNr = TCPSeqNr;
TCPAckNr = 0; // we don't know what to ACK!
TCPUNASeqNr++; // count SYN as a byte
PrepareTCP_FRAME(TCP_CODE_SYN); // send SYN frame
LastFrameSent = TCP_SYN_FRAME;
TCPStartRetryTimer(); // we NEED a retry-timeout
TCPStateMachine = SYN_SENT;
}
break;
}
case SYN_RECD :
case ESTABLISHED :
{
if (TCPFlags & TCP_CLOSE_REQUESTED) // user has user initated a close?
if (!(TransmitControl & (SEND_FRAME2 | SEND_FRAME1))) // buffers free?
if (TCPSeqNr == TCPUNASeqNr) // all data ACKed?
{
TCPUNASeqNr++;
PrepareTCP_FRAME(TCP_CODE_FIN | TCP_CODE_ACK);
LastFrameSent = TCP_FIN_FRAME;
TCPStartRetryTimer();
TCPStateMachine = FIN_WAIT_1;
}
break;
}
case CLOSE_WAIT :
{
if (!(TransmitControl & (SEND_FRAME2 | SEND_FRAME1))) // buffers free?
if (TCPSeqNr == TCPUNASeqNr) // all data ACKed?
{
TCPUNASeqNr++; // count FIN as a byte
PrepareTCP_FRAME(TCP_CODE_FIN | TCP_CODE_ACK); // we NEED a retry-timeout
LastFrameSent = TCP_FIN_FRAME; // time to say goodbye...
TCPStartRetryTimer();
TCPStateMachine = LAST_ACK;
}
break;
}
}
if (TransmitControl & SEND_FRAME2)
{
RequestSend(TxFrame2Size);
if (Rdy4Tx()) { // NOTE: when using a very fast MCU, maybe
_DBG_("Send Frm2");
SendFrame2(); // the EMAC isn't ready yet, include
} else { // a kind of timer or counter here
TCPStateMachine = CLOSED;
SocketStatus = SOCK_ERR_ETHERNET; // indicate an error to user
TCPFlags = 0; // clear all flags, stop timers etc.
}
TransmitControl &= ~SEND_FRAME2; // clear tx-flag
}
if (TransmitControl & SEND_FRAME1)
{
PrepareTCP_DATA_FRAME(); // build frame w/ actual SEQ, ACK....
RequestSend(TxFrame1Size);
if (Rdy4Tx()){ // EMAC ready to accept our frame?
_DBG_("Send Frm1");
SendFrame1(); // (see note above)
} else {
TCPStateMachine = CLOSED;
SocketStatus = SOCK_ERR_ETHERNET; // indicate an error to user
TCPFlags = 0; // clear all flags, stop timers etc.
}
TransmitControl &= ~SEND_FRAME1; // clear tx-flag
}
}
（1）
unsigned int IsBroadcast(void) {
unsigned short RecdDestMAC[3]; // 48 bit MAC
RecdFrameLength = StartReadFrame(); //<1>
CopyFromFrame_EMAC(&RecdDestMAC, 6); //此函數從rptr中順序讀取6個字節到RecdDestMAC，這首6個字節是目標MAC地址
CopyFromFrame_EMAC(&RecdFrameMAC, 6); //再讀6個字節到RecdFrameMAC，是源MAC地址
if ((RecdDestMAC[0] == 0xFFFF) && //如果MAC地址是0xFFFFFFFFFFFF就是廣播地址
(RecdDestMAC[1] == 0xFFFF) &&
(RecdDestMAC[2] == 0xFFFF)) {
return(1);
} else {
return (0);
}
}
<1>
unsigned short StartReadFrame(void) {
unsigned short RxLen;
EMAC_PACKETBUF_Type RxPack;
RxLen = EMAC_GetReceiveDataSize() - 3; //函數將通過狀態寄存器中保存的狀態變量地址中的info字段來判斷幀的長度
// Copy packet to data buffer
RxPack.pbDataBuf = (uint32_t *)pgBuf; //pgBuf = LPC_AHBRAM1_BASE,這是一塊未使用的地址，可用來保存接收的幀數據
RxPack.ulDataLen = RxLen;
EMAC_ReadPacketBuffer(&RxPack);//從寄存器指向的環形緩衝中，拷貝一幀數據到pgBuf
// Point to the data buffer
rptr = (unsigned short *)pgBuf;//用全局rptr變量保存地址
return(RxLen);
}
第二節，分析和協議相關部分
如果不是廣播包，則調用函數
void ProcessEthIAFrame(void)
{
unsigned short TargetIP[2];
unsigned char ProtocolType;
switch (ReadFrameBE_EMAC()) // get frame type 讀取類型字段
{
case FRAME_ARP : // check for ARP
{
if ((TCPFlags & (TCP_ACTIVE_OPEN | IP_ADDR_RESOLVED)) == TCP_ACTIVE_OPEN)
if (ReadFrameBE_EMAC() == HARDW_ETH10) // check for the right prot. etc.
if (ReadFrameBE_EMAC() == FRAME_IP)
if (ReadFrameBE_EMAC() == IP_HLEN_PLEN)
if (ReadFrameBE_EMAC() == OP_ARP_ANSWER)
{
TCPStopTimer(); // OK, now we've the MAC we wanted ;-)
CopyFromFrame_EMAC(&RemoteMAC, 6); // extract opponents MAC
TCPFlags |= IP_ADDR_RESOLVED;
}
break;
}
case FRAME_IP : // check for IP-type
{
if ((ReadFrameBE_EMAC() & 0xFF00 ) == IP_VER_IHL) // IPv4, IHL=5 (20 Bytes Header)
{ // ignore Type Of Service
RecdIPFrameLength = ReadFrameBE_EMAC(); // get IP frame's length
ReadFrameBE_EMAC(); // ignore identification
if (!(ReadFrameBE_EMAC() & (IP_FLAG_MOREFRAG | IP_FRAGOFS_MASK))) // only unfragm. frames
{
ProtocolType = ReadFrameBE_EMAC() & 0xFF; // get protocol, ignore TTL
ReadFrameBE_EMAC(); // ignore checksum
CopyFromFrame_EMAC(&RecdFrameIP, 4); // get source IP
CopyFromFrame_EMAC(&TargetIP, 4); // get destination IP
if (!memcmp(&MyIP, &TargetIP, 4)) // is it for us?
switch (ProtocolType) {
case PROT_ICMP : { ProcessICMPFrame(); break; }
case PROT_TCP : { ProcessTCPFrame(); break; }
case PROT_UDP : break; // not implemented!
}
}
}
break;
}
}
}
看到有人要這個源碼，這個是網上公開可以很容易下到的源碼，這裏附上工程文件
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