Skip to content
An interface and keypad emulator for Digital Security Control's PC1550 Alarm Panel
Branch: master
Clone or download
Latest commit e1e5f0a Dec 21, 2016
Permalink
Type Name Latest commit message Commit time
Failed to load latest commit information.
LICENSE Initial commit Aug 30, 2015
PC1550.cpp Initial commit Aug 30, 2015
PC1550.h Initial commit Aug 30, 2015
README.md

README.md

pc1550-interface

An interface and keypad emulator for Digital Security Control's PC1550 Alarm Panel

This class is a keypad emulator for the Digital Security Control's (DSC) PC1550. The model number of the keypad it emulates is PC1550RK. It should work with any ATmega chipset, and was tested using an Arduino UNO.

With this programmatic interface, you could emulate your own keypad on the device (iPhone maybe?) of your choice. Or you could setup your own monitoring/alerting system (maybe send yourself a text message) when certain alarm events occur.

Hardware Connections

There are four wires that go to the keypad:

Red

        Voltage.  This should be about 12V.  On my system, a
        voltage meter read 13.3V with a brand new battery.  You 
        should be able to safely use this as a power supply for the 
        Arduino.  Simply connect the red line to the pin labeled Vin.  
        The Arduino's internal voltage regulator will take care
        of the rest.  Because the PC1550 has a backup battery
        supply, your Arduino will continue to be powered even
        when the electrity goes out (quite convenient).

Black

        Ground.  If you're using the PC1550 to supply power to
        the Arduino, connect this to the GND pin next to the Vin pin

Yellow

        Clock.  The PC1550 control panel determines the clock cycle.
        So long as the processClockCycle() method on this class is 
        called more frequently than half a clock cycle from the PC1550
        then we will safely be able to read and write signals from
        the PC1550 control panel. The total cycle is about 1500-1600
        micro-seconds, on average (roughly 650 Hz).  Because data 
        is sent when the clock is low and read when the clock is high,
        we must run the processClockCycle() method at least every
        800 micro-seconds.  The more frequently the processClockCycle
        method is called, the more likely data transmission will
        succeed (in both directions) without data loss.  If you're
        not sure if you can commit to a calling the processClockCycle()
        function frequently enough, then you can use 
        processTransmissionCycle() instead which will call 
        processClockCycle() and block until a full transmission cycle
        is complete.  This could be handy if your program is performing
        another task that could use significant clock cycles between
        calls to processClockCycle().  On the downside, 
        processTransmissionCycle() takes between 57ms and 104ms to
        complete.

        Connect the clock line up to either a digital or analog pin.
        We only read on this line using digitalRead, so either a
        digital or analog pin will do.  Analog PIN 4 is the default
        but can be overriden via the constructor to this class.

Green

        Data.  The data line is used to send bits to and from the
        PC1550 when the clock is low and high, respectively.
      
        Connect this line to any analog pin.  While we can read
        data from the panel using only digital functions, we 
        must use analog functions to pull the pin low when we 
        want to send data back to the control panel.  Analog pin 3
        is the default but can be overridden via the contructor.

There is one additional connection that can be made that can provide additional state information from the alarm controller.

Blue

        PGM.  The PGM terminal on the DSC PC1550 control panel
        can be programmed to do a number of things.  One option
        is to configure it as a 2nd data line.  The installation
        manual refers to the PC16-OUT module.  This module reads
        data from the PGM line and we can emulate that module here.
        This line does not go to the keypad, and is optional for
        use by this library.

        For the PGM terminal to work, it will need to be connected to the
        AUX+ terminal with a 1k Ohm resistor (for PC1550s).
        
        Analog pin 1 is the default but can be overridden via the contructor.

See http://www.alarmhow.net/manuals/DSC/Modules/Output%20Modules/PC16-OUT.PDF for a full listing of PGM options.

PC1550 Interface Specification

The PC1550 control panel starts by holding the clock high for roughly 26.5ms. It then clocks out 16 cycles (one cycle is represented by the clock going low and then returning to a high state). After 16 clock cycles, the PC1550 holds the clock high for roughly 26.5ms again, which starts the entire cycle over.

During the 16 clock cycles data is received when the clock is high:

  • The first 8 clock cycles are used to send one octet (byte) of data to the keypad (one bit per clock cycle). This byte contains information about which zones are currently open (what zone lights should display on the keypad). For this reason, the first 8 bits are referred to here as "zone bits."

    The table below shows how the data is received and interpretted. Bit 7 is received first, and bit 0 is recieved last. When bit 7 is on, then the zone 1 light should be on; when bit 6 is on, then the zone 2 light should be on, etc. Bits 1 and 0 are not used.

    Zone Bit    7    6    5    4    3    2    1    0
    Zone        1    2    3    4    5    6  (Not Used)
    
  • The second 8 clock cycles send 8 more bits. This byte contains information about the other lights that should be enabled on the keypad. These bits represent other states and therefore, these bits are referred to here as "state bits."

    The table below shows how each bit is used. Note that when bit 0 is on, the keypad beep emits a short beep.

State Bit 7 6 5 4 3 2 1 0 Ready Armed Memory Bypass Trouble X X Beep

Between receipt of the zone bits, data can be sent back to the control panel when the clock is low. In other words, the panel sends out its bits when the clock is high and the keypad sends back its data when the clock is low.

The keypad only sends back 7 bits-- one bit between each of the 8 zone bits received. These bits represent a button press. When taking the keypad as a table (rows and columns) of buttons, the first three bits received represent the column of the button pressed. The last four bits represent the row of the button pressed:

               First Three Bits               Last 4 Bits
 Column 1      100                    Row 1   0001
 Column 2      010                    Row 2   0010
 Column 3      001                    Row 3   0100
                                      Row 4   1000
                                      Row 5   0000
 No Key        000                            0000 

Encoding bits in the data line: When the data line is LOW the corresponding bit should be ON. When the data line is HIGH the corresponding bit should be OFF.

If the PGM line is connected, then 16 more bits of data are received on this line if (and ONLY IF) the PGM line is configured in PC-16OUT mode. Refer to the PC1550 installation manual for instructions on how to configure this mode. The bits meaning follow:

  • 0 -- PGM Output (whatever the PGM is configured for) ... (This library assumes PGM terminal has been programmed for ... strobe output. This sets bit 0 to the on position ... when the alarm goes off. And the bit remains set until ... the panel is disarmed).
  • 1 -- Fire buttom pressed (on for 4 sec)
  • 2 -- Aux button pressed (on for 4 sec)
  • 3 -- Panic button pressed (on for 4 sec)
  • 4 -- Armed
  • 5 -- Armed
  • 6 -- Armed with bypass (on for 5 sec)
  • 7 -- Trouble
  • 8 -- Fire (on when fire alarm is latched in)
  • 9 -- Not used
  • 10 -- Zone 6 tripped while armed
  • 11 -- Zone 5 tripped while armed
  • 12 -- Zone 4 tripped while armed
  • 13 -- Zone 3 tripped while armed
  • 14 -- Zone 2 tripped while armed
  • 15 -- Zone 1 tripped while armed

For the PGM terminal to work, it will need to be connected to the AUX+ terminal with a 1k Ohm resistor (for PC1550s)

Usage

To use the library, simply do three things:

(1) Include PC1550.h in your Arduino program
(2) Instantiate an instance of the PC1550 instance
(3) call processTransmissionCycle() on the object in each loop

The PC1550 object has a number of methods you may call to determine the state of the lights on the keypad. All the following methods return a boolean value:

  ReadyLight()   -- Indicates whether the keypad's ready light is on
  ArmedLight()   -- Indicates whether the keypad's armed light is on
  MemoryLight()  -- Indicates whether the keypad's memory light is on
  BypassLight()  -- Indicates whether the keypad's bypass light is on
  TroubleLight() -- Indicates whether the keypad's trouble light is on
  Zone1Light()   -- Indicates whether the keypad's zone 1 light is on
  Zone2Light()   -- Indicates whether the keypad's zone 2 light is on
  Zone3Light()   -- Indicates whether the keypad's zone 3 light is on
  Zone4Light()   -- Indicates whether the keypad's zone 4 light is on
  Zone5Light()   -- Indicates whether the keypad's zone 5 light is on
  Zone6Light()   -- Indicates whether the keypad's zone 6 light is on
  Beep()         -- Indicates whether the keypad is beeping

The PC1550 object has a number of methods you may call to determine the state of the alarm based on the PGM output terminal. All the following methods return a boolean value:

  PGMOutput()          -- Indicates the programmable PGMOuput bit is set
  fireButtonTripped()  -- Indicates the fire button on the keypad caused
                          the fire alert to be tripped
  auxButtonTripped()   -- Indicates the aux button on the keypad caused 
                          the aux alert to be tripped
  panicButtonTripped() -- Indicates the panic button on the keypad caused
                          the panic alert to be tripped
  systemArmed()        -- Indicates the system is currently armed
  armedWithBypass()    -- Indicates the system is armed in bypass mode
  systemTrouble()      -- Indicates a trouble situation.  Use the 
                          keypad light methods to deduce the actual 
                          problem
  fireAlarmTripped()   -- Indicates the fire alarm has been tripped
  AlarmTripped()       -- Indicaets the security alarm has been tripped
  Zone1Tripped()       -- Indicates Zone1 tripped since system was armed
  Zone2Tripped()       -- Indicates Zone2 tripped since system was armed
  Zone3Tripped()       -- Indicates Zone3 tripped since system was armed
  Zone4Tripped()       -- Indicates Zone4 tripped since system was armed
  Zone5Tripped()       -- Indicates Zone5 tripped since system was armed
  Zone6Tripped()       -- Indicates Zone6 tripped since system was armed

  keypadStateChanged() -- Indicates the state of the keypad has changed
                          since the last call to processTransmissionCycle()

There are a number of misc methods to provide additional details on the state of the system:

   consecutiveBeeps()      -- The number of clock cycles where a beep has
    		          sounded from the keypad
   consecutiveKeyPresses() -- The number of clock cycles where the same
   			          key has been pressed (and held down)
   atTransmissionEnd()     -- Indicates a full transmission (across 16
                              clock cycles) has been read from the panel
   readyforKeyPress()      -- Indicates the panel is ready for the next
                              keypress

You can simluate a keypress with the following method:

   bool sendKey(char c, int holdCycles)
       where 
          char is the character to send.  Valid values are 
            '1' through '9',
            '#'
            '*'
            'F','A', and 'P'

          holdCycles is the number of cycles across which to simulate
          holding of the key

       returns false if the panel is not ready for a keypress or
       if the character code is not valid.

To read from the panel, call one of the following methods:

    processTransmissionCycle() -- blocks until a full transmission has
                                  been read across 16 clock cycles
    processClockCycle()        -- reads a single clock cycle and release
                                  control so that you may perform other
                                  tasks before the next clock cycle.  You
                                  must call this method every 800us or
                                  data receipt will not be reliable.  If
                                  you are unsure, call 
                                  processTransmissionCycle() instead.

Example

#include <PC1550.h>

PC1550 alarm = PC1550();

void setup() {
   Serial.begin(115200);
}

void loop() {

  //process a full transmisison cycle with the PC1550 controller  
  alarm.processTransmissionCycle();

  //print the state of the keypad and and PGM output to the Serial console
  if (alarm.keypadStateChanged())
     printState();

}


void printState(){
      Serial.print("\n|");
      alarm.ReadyLight() ? Serial.print("R") : Serial.print(" ");
      alarm.ArmedLight() ? Serial.print("A") : Serial.print(" ");
      alarm.MemoryLight() ? Serial.print("M") : Serial.print(" ");
      alarm.BypassLight() ? Serial.print("B") : Serial.print(" ");
      alarm.TroubleLight() ? Serial.print("T|") : Serial.print(" |");
      alarm.Zone1Light() ? Serial.print("1") : Serial.print(" ");
      alarm.Zone2Light() ? Serial.print("2") : Serial.print(" ");
      alarm.Zone3Light() ? Serial.print("3") : Serial.print(" ");
      alarm.Zone4Light() ? Serial.print("4") : Serial.print(" ");
      alarm.Zone5Light() ? Serial.print("5") : Serial.print(" ");
      alarm.Zone6Light() ? Serial.print("6|") : Serial.print(" |");
      alarm.Beep() ? Serial.print("B| ") : Serial.print(" | ");

      alarm.fireButtonTripped()  ? Serial.print("F"):Serial.print(" ");
      alarm.auxButtonTripped()   ? Serial.print("A"):Serial.print(" ");
      alarm.panicButtonTripped() ? Serial.print("P|"):Serial.print(" |");
      alarm.systemArmed() ? Serial.print("Armed   |") : Serial.print("Disarmed|");
      alarm.Zone1Tripped() ? Serial.print("1") : Serial.print(" ");
      alarm.Zone2Tripped() ? Serial.print("2") : Serial.print(" ");
      alarm.Zone3Tripped() ? Serial.print("3") : Serial.print(" ");
      alarm.Zone4Tripped() ? Serial.print("4") : Serial.print(" ");
      alarm.Zone5Tripped() ? Serial.print("5") : Serial.print(" ");
      alarm.Zone6Tripped() ? Serial.print("6") : Serial.print(" ");
      alarm.AlarmTripped() ? Serial.print("|A|") : Serial.print("| |");
 
}
You can’t perform that action at this time.