求教：如何用W5100实现上下位通讯？
最近做一个项目需要通过以太网通讯，想问一下下位在接收是需不需要进行超时判断？如果哪位能提供一个简单的示例，感激不尽。贴一下刚完成的接收函数（未测试）
//W5100 variable define
#define SF_WAIT_FRAME_HEAD 0X01
#define SF_WAIT_FRAME_LEN 0X02
#define SF_WAIT_FRAME_CMD 0X03
#define SF_WAIT_FRAME_DATA 0X04
#define SF_WAIT_FRAME_CHK 0X05
boolean DataReceivedOK = false;
boolean alreadyConnected = false;
boolean EnthernetIsOK = false;
byte PacketBuffer;
unsigned int LocalPort = 8888;
byte mac[] = {0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED};
IPAddress ip(192, 168, 1, 177);
IPAddress gateway(192, 168, 1, 1);
IPAddress subnet(255, 255, 255, 0);
IPAddress Center(192, 168, 1, 113);
// Enter the IP address of the server you're connecting to:
IPAddress server(192, 168, 1, 113);
EthernetServer AlarmServer;
// Initialize the Ethernet client library
// with the IP address and port of the server
// that you want to connect to (port 23 is default for telnet;
// if you're using Processing's ChatServer, useport 10002):
EthernetClient AlarmClient;
byte ReceiveBuf;
byte SendBuf[]={0xaa,0x03,0x05,0x28,0x11,0xbb};
String str="";
void setup()
{
// start the Ethernet connection:
Ethernet.begin(mac, ip);
// Open serial communications and wait for port to open:
Serial.begin(9600);
// if you get a connection, report back via serial:
if (AlarmClient.connect(server, 9050))
{
Serial.println("connected");
}
else
{
// if you didn't get a connection to the server:
Serial.println("connection failed");
}
}
void loop()
{
// if there are incoming bytes available
// from the server, read them and print them:
if (client.available())
{
/*static char sn=0;
static char len=0;*/
char c = client.read();
Serial.println(c);
if (c == 0xaa)
{
Serial.println("Get Frame HEAD 0xAA");
}
else if (c == 0xbb)
{
Serial.println("Get Frame Length 0xBB");
}
else
{
Serial.print("Get other Byte value:");
Serial.println(c);
}
}
// as long as there are bytes in the serial queue,
// read them and send them out the socket if it's open:
while (Serial.available() > 0)
{
char inChar = Serial.read();
if (client.connected())
{
client.print(inChar);
}
}
for(int i=0;i<6;i++)
{
client.write(SendBuf);
}
delay(1000);
// if the server's disconnected, stop the client:
if (!client.connected())
{
Serial.println();
Serial.println("disconnecting.");
client.stop();
// do nothing:
while (true);
}
}
void EthernetInit()
{
Ethernet.begin(mac, ip, gateway, subnet);
AlarmServer.begin();
}
void AlarmServerStart()
{
EthernetClient client = AlarmServer.available();
if (client)
{
if (!alreadyConnected)
{
client.flush();
client.println("Hello,client!");
alreadyConnected = true;
}
if (client.available()>0)
{
char thisChar = client.read();
AlarmServer.write(thisChar);
}
}
}
//连接server
void AlarmClientStart()
{
if (AlarmClient.connected())
{
EnthernetIsOK = true;
Serial.println("Connected");
}
else
{
EnthernetIsOK = false;
AlarmClient.connect(Center, LocalPort);
}
}
//读取一个字节
byte AlarmClientRead()
{
byte c;
if (AlarmClient.available())
{
c = AlarmClient.read();
FrameStateMachine(c);
//Serial.print(c);
}
return c;
}
//接收报文状态机
/*
报文格式：0xAA len cmd datacheck
0xaa : 报文头
len：data区数据长度，不超过20
cmd：命令字，一个byte
data：len个byte
check：校验字，等于len^cmd^data
*/
void FrameStateMachine(byte c)
{
static byte FSState = SF_WAIT_FRAME_HEAD;
static byte len = 0;
static byte CheckSum = 0;
//static byte TimeOutCounts = 0;//超时计数
switch (FSState)
{
case SF_WAIT_FRAME_HEAD:
CheckSum = 0;
len = 0;
if (c == 0xAA)
{
PacketBuffer = c;
FSState = SF_WAIT_FRAME_LEN;
}
break;
case SF_WAIT_FRAME_LEN:
if (c <= 0x14 && c >= 0x00) //数据长度不能大于20个字节
{
PacketBuffer = c;
CheckSum = CheckSum^PacketBuffer;
FSState = SF_WAIT_FRAME_CMD;
}
else
{
FSState = SF_WAIT_FRAME_HEAD;
}
break;
case SF_WAIT_FRAME_CMD:
if (c>0x01 && c<0x40) //command word is between 0x01 and 0x40
{
if (PacketBuffer>0)
{
PacketBuffer = c;
CheckSum = CheckSum^PacketBuffer;
FSState = SF_WAIT_FRAME_DATA;
}
else
{
PacketBuffer = c;
CheckSum = CheckSum^PacketBuffer;
FSState = SF_WAIT_FRAME_CHK; //如果数据长度为0，则进入校验值接收
}
}
else
{
FSState = SF_WAIT_FRAME_HEAD;
}
break;
case SF_WAIT_FRAME_DATA:
PacketBuffer = c;
CheckSum = CheckSum^ c;
len++;
if (len>PacketBuffer)
{
FSState = SF_WAIT_FRAME_CHK;
}
break;
case SF_WAIT_FRAME_CHK:
if (c == CheckSum)
{
FSState = SF_WAIT_FRAME_HEAD;
DataReceivedOK = true;
}
else
{
FSState = SF_WAIT_FRAME_HEAD;
}
break;
default:
FSState = SF_WAIT_FRAME_HEAD;
break;
}
}
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