Chicken Door User Manual Introduction This chicken door incorporates a linear actuator to horizontally slide the existing door of the hen house. The door opens just after dawn and closes just after dusk these times are automatically determined by two light sensors in the chicken run. There is a switch ( close switch ) at the far end of the hen house which is pushed shut when the door is closed, enabling the control box to determine correct movement of the actuator. A motion sensor attached to the hen house will detect movement at night and prevent the door from opening until the area has been checked by a human. An indicator box is positioned outside of the chicken run, and displays the current door status via three coloured lights. Contents Introduction... 1 System Description... 2 Linear Actuator... 2 Power (Electricity)... 3 Control Box... 3 Light Sensors... 4 Close Switch... 4 Motion Sensor... 4 Mode of Operation... 6 Reasoning... 7 Indicator Box... 9 Backup System... 9 Appendix A Indicator Box...10 Appendix B Circuit Schematics...11 Page 1 of 11
System Description What follows is a description of the installed system. Linear Actuator A linear actuator is located horizontally inside the hen house, and uses its full extension to slide the door open and closed. The actuator is branded HIWIN, is rated at up to 24 volts and a strength of 800 Newtons. The actuator is extremely strong and is capable of severe damage if items (such as the ladder) are placed in the way of the door. Note that the linear actuator automatically de-activates once it has reached its full extension this is not controlled by the control box. As a result, any re-location of the linear actuator may cause severe damage to the hen house and chicken door system. The linear actuator is attached to the door via an M8 threaded rod, washers and nuts. This ensures that the link between the door and actuator is rigid. When working near the threaded rod, be careful of the ends as these may present sharp edges. Page 2 of 11
Power (Electricity) The hen house is electrified via an extension cable which exits the house from underneath the computer table in the playroom. It is underneath the surface and clearly marked if working near the cable, be careful not to damage it. The cable enters the hen house through the nearside ventilation gap and terminates inside a green waterproof case on the floor. Inside the waterproof case an adaptor is attached to the end of the extension cable which converts the 240 volt AC to 12 volt DC. A black cable from the adaptor exits the waterproof case and plugs into the control box. The adaptor is originally from an old wireless router, and is capable of providing up to 1.2 amperes of current (12 volts x 1.2 amperes = 14.4 Watts max). This is sufficient for normal running of the linear actuator, but be aware that under heavy loads (i.e. in the event of an obstruction) the actuator will attempt to draw more current from the adaptor. This may damage the adaptor. A spare adaptor is available if this occurs. Note that to convert 240VAC to 12VDC the adaptor radiates a lot of heat this is normal. Control Box The control box contains the power and processing unit which controls the actuator. The control box also provides power to the indicator box and motion sensor. Central to the control box (and entire system) is a Picaxe 28X1 microchip. This chip retrieves and checks light levels, motion alerts and door states, communicates with the indicator box and controls two relays (housed inside the control box) to activate the linear actuator. The control box has a various switches and input/output sockets, as indicated in the image below. FRONT: Socket 1 Power Input This socket accepts the DC connector from the power adaptor. Any DC power source within a voltage range of 9 to 24 volts can be attached here (correct plug is required). This includes heavy duty lead-acid or wet-cell batteries if these are required. FRONT: Switch 1 Power Switch When switched on, provides power from the adaptor to the entire system (including indicator box and linear actuator). Note that the only indication of the power actually being on is through Page 3 of 11
the indicator box, where the lights should be active. There are LEDs inside the control box, but these can only be accessed by unscrewing the lid (not recommended). FRONT: Switch 2 Reset Switch This switch resets the system to the last known door state (see Mode of Operation). A similar function can be achieved by switching off and then switching back on the power to the control box. BACK: Socket 2 Linear Actuator Output This headphone style socket receives the plug from the linear actuator. BACK: Socket 3 Peripheral Socket Input/Output This large socket provides power to the motion sensor and indicator box, in addition to facilitating communications between the light sensors, close switch, motion sensor and indicator box. The control box includes three circuit boards: a power board, the main control board and a drive board (which includes the relays). The schematics for each can be found in APPENDIX. The power board converts the 12VDC into 5VDC for use by the Picaxe and relays. The control board includes the Picaxe and receives all inputs from the sensors and switches. The drive board includes two separate drive circuits in order to provide enough current to actuate the relays. The relays switch the 12VDC for use by the linear actuator (i.e. forward or reverse is set by the relays at the request of the Picaxe). Light Sensors The system includes two light sensors located inside the chicken run. One is positioned underneath the nearside carry-handle of the hen house. The other is affixed to the fence post. The sensors are positioned away from each other to alleviate the risk of localised light conditions triggering a door event. The light sensors are more correctly called light dependent resistors (LDRs). An LDR is a resistor that changes in value according to the light falling on it. Commonly, an LDR has a high resistance in the dark, and a low resistance in the light. This resistance is measure by the Picaxe, and at certain threshold levels the door is either opened or closed. These threshold levels are set in the Picaxe program, and are thus changeable. It should be remembered that the LDR response is not linear in general there is a large resistance change at brighter light levels and this must be accounted for when setting the threshold values. Close Switch This is a simple switch which is used by the control box to determine whether the door is closed. As the door slides shut, the switch is pushed closed. The control box periodically checks the status of the switch to ensure that the door remains closed at night (see Mode of Operation). Motion Sensor The motion sensor used in this system includes a passive infra-red (PIR) sensor, which detects body heat, and a bright LED floodlight. The motion sensor also includes a light sensor, and only operates at night. Page 4 of 11
The motion sensor was purchased at Maplin, and can be used as a stand-alone unit powered by four AA batteries. The unit in the chicken run has been modified to operate from the 5 volts supplied by the control box. A further modification ensures that when the motion sensor is triggered a signal is returned to the control box, in addition to the normal triggering of the LED floodlight. When the motion sensor is triggered, and the control box is satisfied that an intruder is present (see Mode of Operation), the door is disabled and the system goes into hibernate. To wake the system and re-enable the door, it must be reset using the reset switch on the indicator box. This is a design feature ensuring that the area is checked before the system is re-set. When you are away for a length of time and are unable to respond to intruder events, you must switch off the motion detector by setting the switch on the motion detector to the OFF position (see image below). Failure to switch off the motion detector will imprison the chickens inside the hen house until someone resets the system. Once back, reset the motion sensor to AUTO. Page 5 of 11
Mode of Operation The figure below describes the control box operation flow. Normal operation is defined as executing a complete loop without intruder events and door movement, and takes approximately 10 seconds approximately 8 of those seconds are spent pausing or sleeping, mainly to conserve power or wait to interrogate the second light sensor (see Light Levels, below). Page 6 of 11
Reasoning Motion Detector The idea behind the motion sensor is to prevent the door from opening in the morning if an intruder is/has been present, for fear of presenting the chickens directly to a hungry animal. The motion detector only works at night when the door is closed (to prevent accidental triggering by the chickens). The LED floodlight may still switch on before the door is closed but this will not trigger an intruder event and does not have to be reset. To alleviate the risk of cats walking past the chicken run at night triggering an intruder event, the control box will only assume an intruder is present if the motion sensor has been triggered twice within 30 minutes. The first trigger will start a stopwatch, whilst the second will initiate the intruder event. If motion is not detected within 30 minutes after the first trigger, the stopwatch is reset. During an intruder event, the control box disables the door and hibernates. The three LEDs on the indicator box will flash for the entirety of the intruder event. To wake the system the reset button on the indicator box must be briefly depressed. Note that when the motion sensor triggers, or the reset button on the indicator box is depressed, the control box sleeps for approximately 40 seconds. This is in order for the LED floodlight to switch off and/or the person who reset the system to move away from the area, preventing a second intruder event. When the reset button on the indicator box is depressed during an intruder event, all three LEDs will remain solidly lit for approximately 40 seconds whilst the control box re-initialises. Afterwards, the corresponding LED will light (red for door closed, green for door open etc). It is an intentional design decision to locate the rest switch outside near the chicken run this is to prevent re-setting of the system without checking that the area is clear from intruders. When you are away for a length of time and are unable to respond to intruder events, you must switch off the motion detector by setting the switch on the motion detector to the OFF (0) position (see IMAGE). Failure to switch off the motion detector will imprison the chickens inside the hen house until someone resets the system. Once back, reset the motion sensor to AUTO. Light Levels Two light sensors work in unison to determine the current local light levels. During normal operation the first light sensor is read one second before the second. This is an attempt to prevent possible short term light interference (lightening, for example). The readings which the light sensors provide are integer numbers between 0 (pitch black) and 255 (super bright). The control box averages the value of both light sensors and checks these against the threshold values for dawn/dusk. Currently, the threshold values are 170 for dawn and 75 for dusk with these values the door opens approximately 15 minutes after dawn, and closes approximately 30 minutes after dusk. Once a threshold value is reached, the light sensors are interrogated once per second for 20 seconds to ensure that the actual threshold value has been reached. If the light level does not Page 7 of 11
reach the threshold level at any time during these 20 seconds then the control box assumes the threshold level has not been achieved, and continues normal operation. Using torches within the chicken run will not trigger an event unless a torch is shone at each light sensor for over 20 seconds. The LED floodlight, if triggered, will also not trigger an event. Door Motion It is important to note that once the door is moving (either open or closed), there is nothing short of a power failure which will prevent the door from completing its move. If an intruder is detected this will not register until the door has completed its move, and only then will it register if the LED floodlight is still on when the door has completed its move. Once the door has completed its move its status is stored in the internal memory of the control box. This ensures that in the event of a power failure, the control box will still know what position the door is in once power is restored. There are nine different door status codes, outlined below. These are for reference only the user will not come across these codes at the moment. Door Code Description 1 Door open 2 Door closed 3 Door opening 4 Door closing 5 Door open/closed & checking light levels 6 Door probably open, but close switch closed 7 Door probably closed, but close switch open 8 Door position unknown/resetting 9 Intruder event Close Switch The close switch is a physical switch which is pushed closed by the door when closing. During normal operation, the switch is checked for correct positioning. This is achieved by checking the switch position with the door state stored in the control box memory. For example, if the control box memory indicates that the door is closed, the switch should also be closed. If there is a discrepancy between the control box memory and the switch, the control box memory is assumed to be correct. Continuing the example above, if the control box memory indicates that the door is closed, but the switch is in fact open, it is assumed that the door should be closed. The control box will then attempt to re-close the door. This will continue for each loop of normal operation until either the door is completely closed or dawn has been reached and the door should be opened. If this discrepancy frequently occurs, check the state of the close switch there may be obstructions between the contacts. Page 8 of 11
Indicator Box The indicator box is powered by a 5V power cable from the control box. A third cable acts as a communications line between the control box and the indicator box. The indicator box includes four LEDs red, amber and green on the front, and a single white LED on the underside. The red, amber and green LEDs indicate various door and system states, as described in Appendix A Indicator Box. The white LED flashes each time data is sent between the two boxes. The intruder reset switch is also located on the underside of the indicator box. Note that this switch is only active during an intruder event it will not reset the system during normal operation. During an intruder event, depressing the switch briefly will cause the underside white LED to flash and the system to reset within 40 seconds. It is suggested that you leave the area once the reset button has been depressed to avoid triggering a second intruder event. Backup System In the event of a complete system failure, a backup system is provided for use with a mechanical timer. The backup system uses a mechanical timer to provide power to the actuator. On the outside of the switchbox is a toggle switch which reverses the polarity of the current sent to the actuator. This provides control over the direction in which the actuator runs. Once the door is open, the toggle switch must be set to CLOSE. At night, once the door has closed, the toggle switch must be set to OPEN to enable the door to open in the morning. Two slots must be pushed in the mechanical timer, one in the morning when you wish the door to open, and one in the evening when you wish the door to close. The switchbox attaches to the actuator via a headphone-style socket, shown in the image above. Keep the switchbox inside, as it is not waterproof, and run the green cable through the grass into the hen house. Page 9 of 11
Appendix A Indicator Box Indication Description State Startup / Resetting / General Error. 8 Door closed. 2 Door closed & confirming light levels. 5 Door opening. 3 Door open. 1 Door open & confirming light levels. 5 Door closing. 4 Error when opening. Door probably closed. Error when closing. Door probably open. 6 7 Intruder detected. Reset to resume. 9 Page 10 of 11
Appendix B Circuit Schematics Page 11 of 11