gistfile1.c

// Include the SoftwareSerial library so you can use its functions.
// We're using the software serial library as the Arduino only  has one
// hardware serial port, and it's a shame to waste it on a 9600bps device.
#include <NewSoftSerial.h>
#include <Ethernet.h>


// Define the pins used for the software serial port.  Note that we won't
// actually be transmitting anything over the transmit pin.
#define rxPin 3
#define txPin 4

// Set up the serial port
NewSoftSerial softSerial (rxPin, txPin);

byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
byte ip[] = { 10, 0, 0, 2 };
byte gateway[] = { 10, 0, 0, 2 };
byte subnet[] = { 255, 255, 255, 0 };

Server server(23);

int pos = 0;
char startPattern[] = "<ch1><watts>";
char endPattern[] = "<";
int state = 0;
char power[6] = "";
int j;

#define BUFSIZE 256
char buffer[BUFSIZE];
int bufpos = 0;

void setup()  {
  // Define pin modes for tx and rx pins:
  pinMode(rxPin, INPUT);
  pinMode(txPin, OUTPUT);
  // Set the data rate for the SoftwareSerial port
  softSerial.begin(9600);

  // initialize the ethernet device
  Ethernet.begin(mac, ip, gateway, subnet);
  // start listening for clients
  server.begin();

  // Set the data rate for the hardware serial port
  Serial.begin(115200);
}

void loop() {
  Client client = server.available();

  if (softSerial.available()) {

    readLine();

    for (int i = 0; i < BUFSIZE; i++) {
      Serial.print(buffer[i], BYTE);
      if (state == 0) {
	if (buffer[i] == startPattern[pos]) {
	  pos++;
	  if (startPattern[pos] == 0) {
	    // finished matching start pattern
	    state = 1;
	    power[0] = '\0';
	    j = 0;
	  }
	} else {
	  pos = 0;
	}
      } else if (state == 1) {
	if (buffer[i] == endPattern[0]) {
	  // Finished reading power
	  client.write(power);
	  client.write("\n");
	  state = 2;
	  power[0] = '\0';
	  j = 0;
	} else {
	  // Read another digit
	  power[j] = buffer[i];
	  j++;
	}
      }
    }
    state = 0;
    Serial.print("\n");
  }
}

void readLine(void) {
  char c;
  bufpos = 0;
  buffer[0] = '\0';

  while (bufpos < BUFSIZE) {
    if (softSerial.available()) {
      c = softSerial.read();
      buffer[bufpos] = c;
      bufpos++;
    }
  }
  softSerial.flush();
}