Tag Archives: serial

Control Box

Fireworks Control Box

Control Box

This control box receives commands wirelessly via bluetooth and sends commands to the ignition boxes. It is based on the Arduino Mega. A lesser microcontroller can be used, this was chosen due to availability and multiple UART ports. Having more than one will allow the serial bluetooth to stay connected during reprogramming.

The components of this box are

  • Arduino Mega 2560 
  • 2-line display for debugging, status information
  • Break-out board for connections and bluetooth adapter
  • 12V lead-acid battery to power the controller box as well as all the ignition boxes
  • RGB LED strip for status indication & fun

Controller Annotated

Code Overview

The Arduino Mega is programmed using the standard Arduino IDE with the Wire library to communicate to the ignition boxes and LiquidCrystal library for the display.

Setup configures the serial ports, LCD pin configurations, Wire configuration as a master device. In the main loop, read a character from the bluetooth serial port and check for a completed command ending in CR or LF characters. If a command is received, display it, scrolling up to display it. If it is a launch command, call the function to trigger the numbered igniter. Also monitor for a heartbeat and go offline if haven’t received a signal from the tablet in 4 seconds.

When a trigger command is received, the TriggerPin method is called. This will use the Wire library to send a command to the corresponding ignition box to activate the pin for 5 seconds.

Every second the status of every igniter is sent back to the tablet so it can display which outputs are active. A sequence of 100 characters are sent back with ‘0’ = off, ‘1’ = on or ‘2’ for unknown. The sequence is padded out to 100 if fewer igniter boxes are used. An additional code is sent for the controller status if any, and the whole sequence is enclosed in framing brackets ‘[]’.

The loop also handles color animations for the LED strip. The code currently starts up pulsing green, then flashes blue when a bluetooth connection is made. As long as there is a good connection, it will cycle red/white/blue colors. When any igniter is active, it will rapidly flash red and white.

Code Below

#include
#include

// LCD
LiquidCrystal lcd(22,28,29,27,25,23);
char line1[16];
char line2[16];
char line3[16];
int charpos = 0;
char welcome[] = "Ready";

// Serial Bluetooth
unsigned long timeLastSent = 0;
unsigned long timeLastReceived = 0;
boolean launchSequenceStarted = false;
int launchSequenceIndex = 0;
unsigned long timeLastSequence = 0;

// IC2
byte x[3];
boolean igniterOn[80];

enum cmds {
  CMD_WRITE = 1,
  CMD_WRITE_TIMED,
  CMD_STOP_ALL,
  CMD_READ_PINS
};

struct ic2cmd_write {
  byte addr;
  byte val;
};

struct ic2cmd_write_time {
  byte addr;
  int  time;
};

// PWM LED Strip Vars
int redPin = 4;
int greenPin = 3;
int bluePin = 2;
float stripHue = 0;
float currentRed = 0;
float currentGreen = 0;
float currentBlue = 0;
int colorindex = 0;
unsigned long timeLastColor = 0;
int targetRed = 0;
int targetGreen = 0;
int targetBlue = 0;
float deltaRed = 0;
float deltaGreen = 0;
float deltaBlue = 0;
boolean isFading = false;
unsigned long timeLastFade;
int fadeInterval = 10;
enum LEDmode {
  modeStart = 0,
  modeConnect,
  modeOnline,
  modeLaunch
};
int ledMode = modeStart;

// LCD format for LCD display
String formatn(int val)
{
  String ss = "      ";
  val = val % 100000;
  int negadj = (val < 0) ? 1 : 0;
  String sv = String(val);
  String s = ss.substring(sv.length()) + sv;
  return s;
}

// IC2 Send message to slave to activate igniter
void TriggerPin(int pin)
{
  int slavenum = pin / 20;
  ic2cmd_write_time sc;
  sc.addr = pin % 20;
  sc.time = 5000;

  Wire.beginTransmission(4 + slavenum);
  Wire.write(CMD_WRITE_TIMED);
  Wire.write((byte*)&sc, sizeof(sc));              // sends one byte
  Wire.endTransmission();    // stop transmitting
}

// IC2 send message to stop all igniters
void StopAll()
{
  for (int s=0; s<5; s++)
  {
    Wire.beginTransmission(4 + s);
    Wire.write(CMD_STOP_ALL);
    Wire.endTransmission();
  }
  for (int i=0; i<80; i++) igniterOn[i] = false;
}

// LED Strip Red White Blue pattern
void patternRWB(float shift, float bright)
{
//  shift = 0;
  for (byte i=0; i<16; i++)
  {
    float dist = fmod(fabs(shift + i),16);
    float cdist = dist / 2.0;
    int lcolor = int(cdist);
    int rcolor = (lcolor < 7) ? lcolor + 1 : 0;
    float lweight = 1 - (cdist - lcolor);
    float rweight = cdist - lcolor;
    byte r = byte(min((rwbR[lcolor] * lweight + rwbR[rcolor] * rweight) * bright, 127.0));
    byte g = byte(min((rwbG[lcolor] * lweight + rwbG[rcolor] * rweight) * bright, 127.0));
    byte b = byte(min((rwbB[lcolor] * lweight + rwbB[rcolor] * rweight) * bright, 127.0));
    colors[i * 3 + 1] = 0x80 | r;
    colors[i * 3 + 0] = 0x80 | g;
    colors[i * 3 + 2] = 0x80 | b;
  }
  for (int i = 0; i < 48; i++)
  {
    colors[48 + i] = colors[i];
  }
}

void HSVtoRGB( float *r, float *g, float *b, float h, float s, float v )
{
	int i;
	float f, p, q, t;

	if( s == 0 ) {
		// achromatic (grey)
		*r = *g = *b = v;
		return;
	}

	h /= 60;			// sector 0 to 5
	i = floor( h );
	f = h - i;			// factorial part of h
	p = v * ( 1 - s );
	q = v * ( 1 - s * f );
	t = v * ( 1 - s * ( 1 - f ) );

	switch( i ) {
		case 0:
			*r = v;
			*g = t;
			*b = p;
			break;
		case 1:
			*r = q;
			*g = v;
			*b = p;
			break;
		case 2:
			*r = p;
			*g = v;
			*b = t;
			break;
		case 3:
			*r = p;
			*g = q;
			*b = v;
			break;
		case 4:
			*r = t;
			*g = p;
			*b = v;
			break;
		default:		// case 5:
			*r = v;
			*g = p;
			*b = q;
			break;
	}
}

// PWM LED strip color fade to set value
void fadeTo(int r, int g, int b, int t)
{
  targetRed = r;
  targetGreen = g;
  targetBlue = b;
  float dt = t / fadeInterval;
  if (dt < 0.01) {
    deltaRed = (r - currentRed);
    deltaGreen = (g - currentGreen);
    deltaBlue = (b - currentBlue);
  } else {
    deltaRed = (r - currentRed) / dt;
    deltaGreen = (g - currentGreen) / dt;
    deltaBlue = (b - currentBlue) / dt;
  }
  isFading = true;
}

void DoLEDFade()
{
  if (isFading)
  {
    currentRed += deltaRed;
    currentGreen += deltaGreen;
    currentBlue += deltaBlue;
    int red = currentRed;
    int green = currentGreen;
    int blue = currentBlue;
    analogWrite(redPin, red);
    analogWrite(greenPin, green);
    analogWrite(bluePin, blue);
    if (red == targetRed) deltaRed = 0;
    if (green == targetGreen) deltaGreen = 0;
    if (blue == targetBlue) deltaBlue = 0;
    if ((red == targetRed) && (green == targetGreen) && (blue == targetBlue))
      isFading = false;
  }
}

void setup()
{
  // PC Serial setup
  Serial.begin(9600);

  // bluetooth serial setup
  Serial3.begin(9600);

  // LCD setup
  pinMode(24, OUTPUT);
  digitalWrite(24, 0);
  lcd.begin(16,2);
  // clear buffers
  memcpy(line1, 0, 16);
  memcpy(line2, 0, 16);
  memcpy(line3, 0, 16);
  // print ready message
  lcd.setCursor(0,0);
  lcd.print(welcome);

  // 2-Wire slave communication setup
  Wire.begin(); // join i2c bus (address optional for master)
  memset(x, 0, sizeof(x));
  x[0] = 1;
  x[1] = 1;
  for (int i=0; i<80; i++) igniterOn[i] = false;

  // SPI LED Strip setup
  SPI.begin();
  SPI.setClockDivider(SPI_CLOCK_DIV2);
  SPI.setBitOrder(MSBFIRST);
  rwbR[0] = 30; rwbG[0] = 0;  rwbB[0] = 0;
  rwbR[1] = 30; rwbG[1] = 0;  rwbB[1] = 0;
  rwbR[2] = 10; rwbG[2] = 10; rwbB[2] = 10;
  rwbR[3] = 10; rwbG[3] = 10; rwbB[3] = 10;
  rwbR[4] = 0;  rwbG[4] = 0;  rwbB[4] = 30;
  rwbR[5] = 0;  rwbG[5] = 0;  rwbB[5] = 30;
  rwbR[6] = 00; rwbG[6] = 00; rwbB[6] = 30;
  rwbR[7] = 30; rwbG[7] = 00; rwbB[7] = 00;
  patternRWB(0.0, 1.0);
}

void loop() {
  unsigned long timenow = millis();
  // Read input from bluetooth serial
  if (Serial3.available()) {
    char c = Serial3.read();
    Serial.write(c); // echo to PC
    if ((charpos == 16) || (c == 13)) {
      timeLastReceived = timenow;

      // if this is the 2sec heartbeat, throw away text reset row 3
      if (strncmp(line3, "Online", 6) == 0)
      {
        for (int i = 0; i < 16; i++) {
          line3[i] = 0;
          charpos = 0;
        }
      } else {

        // received end of line, shift line buffers
        for (int i = 0; i < 16; i++) {           line1[i] = line2[i];           line2[i] = line3[i];           line3[i] = 0;         }            // Refresh display         lcd.setCursor(0,0);         lcd.print("                ");         lcd.setCursor(0,0);         lcd.print(line1);         lcd.setCursor(0,1);         lcd.print("                ");         lcd.setCursor(0,1);         lcd.print(line2);         charpos = 0;            // Execute commands         if (strncmp(line2, "Launch ", 7) == 0)         {           int index = atoi(&line2[7]);           TriggerPin(index);           ledMode = modeLaunch;           colorindex = 0;            /* // No launch squencing for 2013           // check for launch sequence start           if (index == 76)           {             launchSequenceStarted = true;             launchSequenceIndex = 76;             timeLastSequence = timenow;           } */   //        Serial.write(line2);         } else if (strncmp(line2, "Stop", 4) == 0)         {   //        Serial.write("Stopping All\n");           StopAll();         }       }     }        // Add received character to buffer     if (c >= ' ' && c <= 'z') {       line3[charpos] = c;       charpos++;     }   }   // check for sequencing   if (launchSequenceStarted && (timenow - timeLastSequence > 20000))
  {
    timeLastSequence = timenow;
    launchSequenceIndex++;
    TriggerPin(launchSequenceIndex);
    ledMode = modeLaunch;
    colorindex = 0;
    if (launchSequenceIndex == 80)
      launchSequenceStarted = false;
  }

  // if we got a signal but in start mode switch to connect mode
  if ((ledMode == modeStart) && (timeLastReceived > 0) && (timenow - timeLastReceived < 500))   {     ledMode = modeConnect;     colorindex = 0;   }      if ((ledMode == modeOnline) && (timenow - timeLastReceived > 4000))
  {
    ledMode = modeStart;
    colorindex = 0;
  }
/*
  if (Serial.available())
    Serial3.write(Serial.read());
*/

//  lcd.setCursor(0,0);
//   lcd.print(formatn(timenow));

  // Once a second, get status from slaves and send over bluetooth
  if ((timenow - timeLastSent) >= 1000)
  {
//    Serial.write("Checking Slaves\n\r");
    // send updates once a second
    timeLastSent = timenow;
    Serial3.write("["); // framing value
    Serial3.write("2"); // System code

    for (int s = 0; s < 4; s++)
    {
      Wire.requestFrom(4 + s, 20);
      byte nread = 0;
      while (Wire.available())
      {
        byte b = Wire.read();
        Serial3.write('0' + b);
        nread++;
      }
      for (int i = nread; i < 20; i++)         Serial3.write('2');           }     Serial3.write("]\r\n"); // framing value   }      // PWM LED strip   if (timenow - timeLastFade > fadeInterval)
  {
    DoLEDFade();
    timeLastFade = timenow;
  }

  switch (ledMode) {

    case modeStart:
    {
      if ((timenow - timeLastColor) > 2000)
      {
         timeLastColor = timenow;
         colorindex++;
        if (colorindex >= 2) colorindex = 0;
        switch (colorindex)
        {
          case 0: fadeTo(0, 0, 0, 1600); break;
          case 1: fadeTo(0, 50, 0, 1600); break;
        }
      }
    } break;

    case modeLaunch:
    {
      if ((timenow - timeLastColor) > 100)
      {
         timeLastColor = timenow;
         switch (colorindex % 2)
         {
            case 0: fadeTo(80, 80, 80, 20); break;
            case 1: fadeTo(120, 0, 0, 20); break;
         }
         colorindex++;
        if (colorindex >= 30)
        {
          colorindex = 0;
          ledMode = modeOnline;
        }
      }
    } break;

    case modeConnect:
    {
      if ((timenow - timeLastColor) > 300)
      {
         timeLastColor = timenow;
         switch (colorindex)
         {
            case 0: fadeTo(0, 0, 100, 200); break;
            case 1: fadeTo(0, 0, 0, 100); break;
            case 2: fadeTo(0, 0, 100, 200); break;
            case 3: fadeTo(0, 0, 0, 100); break;
        }
         colorindex++;
        if (colorindex >= 3)
        {
          colorindex = 0;
          ledMode = modeOnline;
        }
      }
    } break;

    case modeOnline:
    {
      if ((timenow - timeLastColor) > 3000)
      {
        timeLastColor = timenow;
        colorindex++;
        if (colorindex >= 3) colorindex = 0;
        switch (colorindex)
        {
          case 0: fadeTo(100, 0, 0, 1500); break;
          case 1: fadeTo(50, 50, 50, 1500); break;
          case 2: fadeTo(0, 0, 100, 1500); break;
        }
      }
     } break;
  }

}

Fireworks Ignition Box

Ignition Box

Ignition Box

This box receives commands from the control box and powers the nichrome based fuses.

Microcontroller

An Atmel ATMEGA328P was used to for the ignition control. This is the same family of controller as the Arduino, so can reuse libraries from that project. In addition to the price and size savings over an Arduino board, more I/O points are available if the fuses are reprogrammed to remove the use of the RESET pin for I/O instead. All 23 of the available data pins are used, the other 5 pins of the 28 pin package are for voltage. This allows for 20 igniter controls, 2 communication pins (SCL/SDA for clock/data), and one pin for an indicator LED control.

Ignite Box Annotate

Screen Shot 2013-07-06 at 5.16.05 PM

Switch & LED circuit

Each igniter is connected on one side to +12V via the safety cut-off switch. The other side connects to the drain of a low side FET switch. The source of the FET is connected to ground, when the controller activates the gate by going high, a full 12V is placed across the igniter and it heats up.

When there is an igniter connected, a small amount of current will flow from the 12V supply to the 5V supply, lighting the green LED indicating a closed circuit. When the control is activated, the low side of the LEDs in the diagram are brought to ground, causing the red LED to light, indicating the switch is active.

A couple notes about this LED setup: First, there will be a reverse voltage of up to 7V across the LED, make sure the chosen LEDs can support that. Secondly, with all 20 igniters connected, 20 green LEDs will light, causing tens of mA to flow from the 12V to the output side of the 5V regulator which will cause problems for the regulator. To offset that current, additional LEDs are placed between the 5V supply and ground to drain off that current. This also adds some illumination to the box, as seen by the colored lights under each box in the photo below.

Ignition boxes

Ignition boxes

Programming

The program is compiled using AVR studio from Atmel. Instructions on how to program the chips can be found here. This will use the Wire library for serial communications with the controller box, you can copy that library from Arduino.

This is a slave device to the control box, it waits to receive a serial command from the controller. It should get a request every second, if not, it is considered off-line.

Setup configures the pins for output and registers the callbacks for the serial data received event. The controller currently sends two types of commands, either to turn on an output for a specified number of seconds, or to turn off all pins. Each box needs to be programmed with a different serial ID number so they can be addressed separately by the controller, this is done in the Wire.begin(x) call.

The main loop will check if it is time to turn off any pins that have timers set. It will also blink the indicator light depending on the state of the system communications. A serial read request will return the state of all the output pins.

Source code below

#include <avr/io.h>
#include "Arduino.h"
#include <Wire.h>

// pin map so that igniters can be numerically ordered counter clockwise around the chip
byte pinMap[20] = {0, 1, 2, 3, 4, 14, 15, 5, 6, 7, 8, 9, 10, 11, 12, 13, 16, 17, 18, 19};
void receiveEvent(int howMany);
void requestEvent();
unsigned long pinOffTime[20];
unsigned long lastBlinkTime;
unsigned long lastRequestTime;
unsigned int blinkLength = 200;
bool blinkOn;
const byte blinkPin = 22;

bool isIgniting = false;

enum cmds {
CMD_WRITE = 1,
CMD_WRITE_TIMED,
CMD_ALL_OFF,
CMD_READ_PINS
};

struct spicmd_write {
byte addr;
byte val;
};

struct spicmd_write_time {
byte addr;
unsigned int  time;
};

// run once, when the sketch starts
void setup()
{
  pinMode(22, OUTPUT);
  blinkOn = false;
  digitalWrite(22, 0);

  // Set each slave controller to unique address
  Wire.begin(7);                // join i2c bus with address #4 for first slave, 5 for second, etc..
  Wire.onReceive(receiveEvent); // register event
  Wire.onRequest(requestEvent);

// set the digital pin as output
  for (int i = 0; i < 20; i++)
  {
    pinMode(pinMap[i], OUTPUT);
    digitalWrite(pinMap[i], 0);
    pinOffTime[i] = 0;
  }
}

// run over and over again
void loop()
{
  unsigned long now = millis();
  // check if any timed pins should be shut off
  bool anyIgniting = false;
  for (int i = 0; i < 20; i++)
  {
    if (pinOffTime[i] != 0)
    {
      anyIgniting = true;
      if (now > pinOffTime[i])
      {
        pinOffTime[i] = 0;
        digitalWrite(pinMap[i], 0);
      }
    }
  }
  isIgniting = anyIgniting;

  if (now >= lastBlinkTime + blinkLength)
  {
    lastBlinkTime = now;
    blinkOn = !blinkOn;
    digitalWrite(blinkPin, blinkOn ? 0 : 1);
    // if igniting blink fast
    if (isIgniting) {
      blinkLength = 100;
    } else {
      if (now < lastRequestTime + 1500) {
        blinkLength = blinkOn ? 500 : 500; // good connection blink 1 sec
      } else {
        blinkLength = blinkOn ? 100 : 900; // no connection mostly off, blink momentarily
      }
    }
  }
delay(1);
}

// function that executes whenever data is received from master
// this function is registered as an event, see setup()
void receiveEvent(int howMany)
{
  if (Wire.available() == 0) return;

  byte data[8];
  for (int i = 0; i < howMany; i++) {
    data[i] = Wire.read();
  }

  byte command = data[0];

  // command 1 set an output pin
  if (command == CMD_WRITE) {
    // must be 3 bytes: command, pin, on/off
    if (howMany - 1 != sizeof(spicmd_write)) return;
    spicmd_write *cdata = reinterpret_cast<spicmd_write*>(&data[1]);
    digitalWrite(pinMap[cdata->addr], cdata->val != 0);
    isIgniting = true;
  }
  // command 1 set an output pin on, timed shutoff
  else if (command == CMD_WRITE_TIMED)
  {
    // must be 3 bytes: command, pin, on/off
    if (howMany - 1 != sizeof(spicmd_write_time)) return;
    spicmd_write_time *cdata = reinterpret_cast<spicmd_write_time*>(&data[1]);
    digitalWrite(pinMap[cdata->addr], 1);
    pinOffTime[cdata->addr] = millis() + cdata->time;
    isIgniting = true;
  }
  else if (command == CMD_ALL_OFF)
  {
    for (int i=0; i<20; i++)
    {
      digitalWrite(pinMap[i], 0);
      pinOffTime[i] = 0;
    }
  }
}

void requestEvent()
{
  byte state[20];
  for (int i = 0; i < 20; i++) {
    state[i] = digitalRead(pinMap[i]);
  }
  Wire.write(state,20);
  lastRequestTime = millis();
}

// arduino main
int main(void)
{
  init();
  setup();

  for (;;)
    loop();

  return 0;
}

Twitter Water Sensor Software

Start with the modules programmed, wired and plugged in as described in the last 2 posts. The modules should be communicating and sending the sensor samples. We now need to read the data from the serial port and write a tweet when the sensor indicates a low on DIO4. Before writing and running this code, you will need to have set up a Twitter account and set up an Application. Then follow this account from your main twitter account, enabling mobile messaging if you want to receive a text message when an event occurs.

This is developed on Ubuntu, but using the Perl scripting language that should be portable to other platforms. Use CPAN to install the dependent modules:

  • Device::SerialPort for communications with the XBee
  • Tie::CharArray for splitting a string into a character array
  • Net::Twitter  provides a class to interface with Twitter

Open and read data from the serial port. We convert the received binary string into a character array of the ordinal values for easier processing. Then copy characters read into a processing buffer so we can handle multiple reports coming in a single read or partial reads.

my $port=Device::SerialPort->new("/dev/ttyS0");</pre>
while ($timeout>0)
{
	my ($count,$saw)=$port->read(255); # will read _up to_ 255 chars
	tie my @chars, 'Tie::CharArray::Ord', $saw; 
	for ($i = 0; $i < $count; $i++) {
		push(@buffer, @chars[$i]);
		printf("0x%02x ", @buffer[$i]);
	}

We then run a series of checks on the header information to verify the packet is received correctly. First check the header character for proper framing, or throw away characters until we find the next frame header.

	# check frame header
	if (@buffer[0] != 0x7e) {
		printf("Bad Frame\n");
		shift(@buffer);
		next;
	}

Then verify all the characters expected have been received by checking the packet size.

	# check all chars are now in buffer
	$size = @buffer[2] + @buffer[1] * 0x100;
	printf("Size:     %d\n", $size);
	if ($size > scalar(@buffer) - 4) { next; }

Then verify the contents of the package by running the checksum operation.

	# check checksum
	$sum = 0;
	for ($i = 0; $i < $size ; $i++) {
		$sum += @buffer[$i + 3];
	}
	$sum = 0xff - $sum % 0x100;
	if ($sum != @buffer[$size + 3]) {
		printf("Checksum: FAIL %02x != %02x\n", $sum, @buffer[$size + 3]);
		next;
	} else {
		printf("Checksum: PASS %02x\n", $sum);
	}

If contents are complete and intact, copy message to a packet buffer.

	my @packet;
	for ($i = 0; $i < $size + 4 ; $i++) {
		push(@packet, @buffer[$i]);
	}

If an packet received is an IO sample packet, process the IO message. Then remove this packet from the input buffer.

	if (@buffer[3] == 0x92) {
		ProcessIO(\@packet);
	}
	for ($i = 0; $i < $size + 4; $i++) {shift(@buffer);} 

In the ProcessIO sub routine, extract the packet information. Fetch the device ID of the sending XBee, the 16 bit ID, packet type, and read digital IO 4.

  
sub ProcessIO {
	my @packet = @{(shift)};
	
	my $xbeeid = sprintf("%02x%02x%02x%02x%02x%02x%02x%02x", @packet[4], @packet[5], @packet[6],
		@packet[7], @packet[8], @packet[9], @packet[10], @packet[11]);
	printf("DeviceID: %s\n", $xbeeid);

	printf("Net MyID: %02x%02x\n", @packet[12], @packet[13]);
	
	printf("PackType: %02x\n", @packet[14]);
	
	my $dio4 = (@packet[20] & 0x10) != 0;

Once we have this information, we compare the device ID to verify it is the sensor device we are interested in. Then check if the DIO4 line has been brought low from previously being high since we only want to tweet the first time water is detected, not every second. This code is taken from the sample code in the Net::Twitter documentation. Net::Twitter->new creates and authenticates a connection with Twitter, then ->update posts a tweet. A time stamp is added to the message, otherwise it may be rejected as a duplicate tweet.

 	if ($xbeeid eq $xbee_basement) 	{ 		if (($dio4 == 0) && ($last_water == 1)) 		{ 			printf("DETECTED WATER!!\n"); 			my $nt = Net::Twitter->new(
				traits   => [qw/OAuth API::REST WrapError/],
				consumer_key        => $consumer_key,
				consumer_secret     => $consumer_secret,
				access_token        => $token,
				access_token_secret => $token_secret,
			);

			$now_string = strftime "%H:%M", localtime;
			$tweet = sprintf("At %s Basement sensor 4 detected water", $now_string);

			my $result = $nt->update($tweet);
			#print Dumper $result;
		}
		$last_water = $dio4;

Then just run the script from a terminal.
Perl xbee.pl

use Device::SerialPort;
use Tie::CharArray;
use Net::Twitter;
use Data::Dumper;
use POSIX qw(strftime);

 my $port=Device::SerialPort->new("/dev/ttyS0");

 my $STALL_DEFAULT=60; # how many seconds to wait for new input

 my $timeout=$STALL_DEFAULT;

my $consumer_key = "your consumer key";
my $consumer_secret = "your consumer secret";
my $token = "your token";
my $token_secret = "your token secret";
my $xbee_basement = "0013a200400a1896";

 $port->read_char_time(0);     # don't wait for each character
 $port->read_const_time(500); # 1 second per unfulfilled "read" call
 my $last_water = 1;

 sub ProcessIO {
	my @packet = @{(shift)};

	my $xbeeid = sprintf("%02x%02x%02x%02x%02x%02x%02x%02x", @packet[4], @packet[5], @packet[6],
		@packet[7], @packet[8], @packet[9], @packet[10], @packet[11]);
	printf("DeviceID: %s\n", $xbeeid);

	printf("Net MyID: %02x%02x\n", @packet[12], @packet[13]);

	printf("PackType: %02x\n", @packet[14]);

	my $dio4 = (@packet[20] & 0x10) != 0;

	if ((@packet[16] & 0x04) != 0) { printf("DIO10:   %d\n", (@packet[19] & 0x04) != 0); }
	if ((@packet[16] & 0x08) != 0) { printf("DIO11:   %d\n", (@packet[19] & 0x08) != 0); }
	if ((@packet[16] & 0x10) != 0) { printf("DIO12:   %d\n", (@packet[19] & 0x10) != 0); }
	if ((@packet[17] & 0x01) != 0) { printf("DIO0:    %d\n", (@packet[20] & 0x01) != 0); }
	if ((@packet[17] & 0x02) != 0) { printf("DIO1:    %d\n", (@packet[20] & 0x02) != 0); }
	if ((@packet[17] & 0x04) != 0) { printf("DIO2:    %d\n", (@packet[20] & 0x04) != 0); }
	if ((@packet[17] & 0x08) != 0) { printf("DIO3:    %d\n", (@packet[20] & 0x08) != 0); }
	if ((@packet[17] & 0x10) != 0) { printf("DIO4:    %d\n", $dio4); }
	if ((@packet[17] & 0x20) != 0) { printf("DIO5:    %d\n", (@packet[20] & 0x20) != 0); }
	if ((@packet[17] & 0x40) != 0) { printf("DIO6:    %d\n", (@packet[20] & 0x40) != 0); }
	if ((@packet[17] & 0x80) != 0) { printf("DIO7:    %d\n", (@packet[20] & 0x80) != 0); }
	$as = 21;
	if ((@packet[18] & 0x01) != 0) { my $val = @packet[$as++] * 0x100 + @packet[$as++]; printf("AD0:    %4x\n", $val); }
	if ((@packet[18] & 0x02) != 0) { my $val = @packet[$as++] * 0x100 + @packet[$as++]; my $cval = $val * 100.0 / 0x3ff; printf("AD1:    %4x %4.1fC %4.1fF\n", $val, $cval, $cval * 9 / 5 + 32); }
	if ((@packet[18] & 0x04) != 0) { my $val = @packet[$as++] * 0x100 + @packet[$as++]; printf("AD2:    %4x\n", $val); }
	if ((@packet[18] & 0x08) != 0) { my $val = @packet[$as++] * 0x100 + @packet[$as++]; printf("AD3:    %4x\n", $val); }
	if ((@packet[18] & 0x80) != 0) { my $val = @packet[$as++] * 0x100 + @packet[$as++]; printf("VSS:    %4x\n", $val); }

	if ($xbeeid eq $xbee_basement)
	{
		if (($dio4 == 0) && ($last_water == 1))
		{
			printf("DETECTED WATER!!\n");
			my $nt = Net::Twitter->new(
				traits   => [qw/OAuth API::REST WrapError/],
				consumer_key        => $consumer_key,
				consumer_secret     => $consumer_secret,
				access_token        => $token,
				access_token_secret => $token_secret,
			);

			$now_string = strftime "%H:%M", localtime;
			$tweet = sprintf("At %s Basement sensor 4 detected water", $now_string);

			my $result = $nt->update($tweet);
			#print Dumper $result;
		}
		$last_water = $dio4;
	}
 }

 my @buffer;
 while ($timeout>0)
 {
	my ($count,$saw)=$port->read(255); # will read _up to_ 255 chars
	tie my @chars, 'Tie::CharArray::Ord', $saw;
	for ($i = 0; $i < $count; $i++) { 		push(@buffer, @chars[$i]); 		printf("0x%02x ", @buffer[$i]); 	} 	if ($count > 0) { printf("\n"); }

	if (scalar(@buffer) == 0) { next; }

	# check frame header
	if (@buffer[0] != 0x7e) {
		printf("Bad Frame\n");
		shift(@buffer);
		next;
	}

	# check all chars are now in buffer
	$size = @buffer[2] + @buffer[1] * 0x100;
	printf("Size:     %d\n", $size);
	if ($size > scalar(@buffer) - 4) { next; }

	# check checksum
	$sum = 0;
	for ($i = 0; $i < $size ; $i++) {
		$sum += @buffer[$i + 3];
	}
	$sum = 0xff - $sum % 0x100;
	if ($sum != @buffer[$size + 3]) {
		printf("Checksum: FAIL %02x != %02x\n", $sum, @buffer[$size + 3]);
		next;
	} else {
		printf("Checksum: PASS %02x\n", $sum);
	}

	my @packet;
	for ($i = 0; $i < $size + 4 ; $i++) {
		push(@packet, @buffer[$i]);
	}

	printf("Command:  %02x\n", @buffer[3]);
	if (@buffer[3] == 0x92) {
		ProcessIO(\@packet);
	}

	# Check here to see if what we want is in the $buffer
	# say "last" if we find it
	for ($i = 0; $i < $size + 4; $i++) {shift(@buffer);}
	$timeout = $STALL_DEFAULT;
}

 if ($timeout==0) {
        die "Waited $STALL_DEFAULT seconds and never saw what I wanted\n";
 }

Parsing Misterhouse Serial Data

The sensors transmit data in the form “Address,Port,Value” A typical input would be “A1,T1,30.0″ for module 1, temperature sensor 1, and 30 deg C.

In this case only temp data is read by this. split is used to segment the three elements, the temperature is converted to Fahrenheit, and the result stored in a hash.

$xbee_serial = new Serial_Item(undef, undef, 'serial1');
if (my $data = said $xbee_serial)
{
	my @values = split(',', $data);
	my $temp = $values[2] * 9 / 5 + 32;
	$xbee_data{ $values[0].$values[1] } = $temp;
}