An Arduino Based. Motorised Pool Cover. Controller

Transcription

1 An Arduino Based Motorised Pool Cover Controller Version.02 December 203 Copyright Chris Gaebler 203 This document or any derivative of it may be freely copied and distributed in any form.

2 Contents Contents...2 Introduction...3 Overview...3 Original Controllers...4 Motors...4 Sensors...4 Wiring...4 Overview of the Arduino System...5 Cabling and Connectors...6 Pinouts for Sensor D connectors...6 Pinouts for Motor D connectors...6 Pinouts for key and remote D connector...7 Original Left-Right 6-core Cable...7 New Left-Right Cable...7 Sensor Cables...7 The Sensor Wiring Harness...8 The Key Switch and Remote Control Harness...9 The Remote Control...0 The Relay Boxes... Cables...2 The Manual Switch Box...4 The Charger Module...5 The Input Module...6 Regulators and voltage monitoring...6 Buzzer Output...6 Switch Inputs...6 Key and Remote Control Input...7 Sensor Inputs...8 Buzzer...8 Stripboard Layout...9 The Control Box...20 Arduino Connections...20 The 8-Channel Relay Module...20 Construction...23 Parts List...23 Control Box Cutout Templates...24 Installing the Software...24 Testing the Relay Boxes...24 Testing the Control Box...24 Installation...26 Right Side...26 Left Side...26 Commissioning...27 Adjusting the Fully Closed Sensors...27 Normal Operation...29 A Few Maintenance Tips

3 Introduction The electronic controllers for the Abrisud motorised pool cover are unreasonably prone to failure and unreasonably expensive to replace. The first time ours failed, in 20, after 3 years use, they cost 400 to replace. When they failed again in 203 we were quoted,200 to replace them. We declined. This paper documents the replacement of the original controllers with a home-made system based on an Arduino micro-controller. The total cost of all the parts required for the system described here is well under 00, and we expect our system to be more durable and reliable than the original controllers. But this is not a "beginner's" project. It will take several days to build and requires considerable skill with a soldering iron. Overview The pool cover has several sections, each with an aluminium frame and polycarbonate sheeting. Motors retract each section in turn, then lift it so that the next section can retract beneath it. When fully open, all four sections are stacked on top of each other at one end of the pool, leaving the pool completely open. To close the cover, the motors roll out each section in turn, before lowering the next section down, ready to roll out. The system has two motor housings at one end of the pool. Each housing contains a 2v 2 AH sealed lead acid battery, two motors, three micro-switches, and an electronic controller. The two sides are identical except that one side also has the key switch and the power supply for charging the batteries. The controllers communicate with each other via a 6-core cable that runs underground between the two motor housings. Key Left Side Lift Fully Open Move Fully Lifted Right Side Pool Fully Closed Controllers Sensors Motors 3

4 Original Controllers The original system uses two identical proprietary controllers, one each side, connected together by a 6core cable. Each controller processes the input from its three sensors and manages four relays to control its two bi-directional DC motors. The original controllers allow moisture and insects to get in and cause corrosion of the printed circuit board tracks, leading to failure after as little as two years. Motors The motors are 2 volts DC, and can run in either direction. The Move Motor moves the cover sections backwards and forwards. The Lift Motor lifts and lowers the sections. Sensors There are three micro-switches on each side, all normally open: Fully Closed: Closes when a cover section reaches its correct closing position, i.e. ready for the next section to be lowered onto it. The exact closing position can be adjusted. Fully Open: Closes when each cover section reaches its fully open position, i.e. at the back of the motor housing, ready to be lifted. When the section is lifted, this switch opens again. When a section is lowered, this switch closes. Fully Lifted: Closes when the lift mechanism reaches the top of its travel. On the right hand side there is also a key switch, which is normally open. The user turns the key to the right to open the cover, and to the left to close it. An optional remote control can be wired in parallel with the key. So there are a total of 6 micro-switches and 2 key inputs, making 8 inputs in total. Wiring The original wiring uses Molex Mini-Fit connectors: The sensors have male 2-way Molex Mini-Fit connectors. Both motors on each side are wired to a single male 4-way Molex Mini-Fit connector. The key switch has a male 4-way Molex Mini-Fit connector. The remote control receiver has a male 4-way Molex Mini-Fit connector. These connectors plug directly into the controllers, but this is part of the problem, because they do not allow the controllers to be properly sealed. A 6-core cable runs from the left motor housing to the right motor housing 4

5 Overview of the Arduino System The replacement controller is based on a single Arduino Uno. An 8 channel relay module powers the relays that control the motors. An additional Relay Box on each side of the pool powers the motors from the local battery. A custom-made Input Module has power regulators and the components that stabilise the sensor inputs as well as a few other components. A separate Charge Module keeps the batteries on a permanent float charge. Left Relay Box Right Relay Box Charge Module Control Box 8-Channel Relay Module Input Module Key Switch Left Sensors Arduino Uno Right Sensors 5

6 Cabling and Connectors To avoid modifying the existing motor and sensor wiring, we connect to them using the Molex Mini-Fit connectors recovered from the original controllers. These are used to create new wiring harnesses that connect to the DB9 connectors used in the new system. DB9 connectors are chosen for the new Control Box because they are reliable and enable the box to be completely sealed against moisture and insects. This picture is looking into the open end of a male DB9 connector. The following diagram shows the connectors used in the new system (M for Male, F for Female). Note that a new cable is required from the left motor housing to the right motor housing in addition to the original 6-core cable. Left Side Left motor relay box with DB9 male Right Side Right sensors 2 3 Left sensors 2 3 Original 6-core cable M key & remote M F M F M M F F F M F M Control Box with 5 female DB9 connectors F Right motor relay box with DB9 male New 4-core cable Coloured tape is used to identify the cables to avoid errors during maintenance. Pinouts for Sensor D connectors = Ground 2 = Fully Open 3 = Fully Closed 4 = Fully Lifted Pinouts for Motor D connectors = Ground 2 = Move Open 3 = Move Close 6

7 4 = Lift Up 5 = Lift Down 6 = 2 volts (supplied from the relay boxes) Pinouts for key and remote D connector = Ground 2 & 3 = Open 4 & 5 = Close 6 & 7 = 2 volts Original Left-Right 6-core Cable The right side relay board is connected to the left side motor casing using the original 6-core cable, which is fitted with a female DB9 connector on the right side and a male DB9 connector on the left side, as follows: DB9 Pin Cable Colour Thick black Thin yellow Thin green Thin red Thin white Thick red Function Ground Move open Move close Lift up Lift down +2 volts charge voltage New Left-Right Cable Since the new system has only a single controller (on the left side), a new cable must be run from the left side to the right side, containing at least four cores. It only carries a few milliamps so cat5 cable can be used, although a multi-stranded cable would be easier to work with. It has a female DB9 connector on the right side and a male DB9 connector on the left side, with the following pinout: DB9 Pin Cat 5 cable colour Brown+white Green+white Blue+white Brown Green Blue Function Ground Fully Open Fully Closed Fully Lifted Sensor Cables The sensors in our system are identified by coloured tape as follows: Fully Open Fully Closed Fully Lifted Yellow tape Black tape Blue tape 7

8 The Sensor Wiring Harness The sense switches are wired to Molex Mini-Fit 2-pin connectors, each side having three sense switches. We need two identical wiring harnesses, one for each side. Each harness connects three Molex 2-pin connectors to one 9 pin male D connector. The original sensor cables plug in to the Molex connectors. The harness takes a 2 volt feed from the local battery, so that the sense switches provides 2 volts to the Control Box when activated. The 9 pin D connector on the left side plugs directly into the Control Box. The 9 pin D connector on the right side is extended by the new (cat-5) cable running from the left side to the right side. 8

9 The Key Switch and Remote Control Harness The key switch and remote control are wired with Molex Mini-Fit 4-pin connectors. The pinout is:. Grey = Close 2. Brown = Open 3. Orange = 2volts 4. Blue = Ground The key switch connects pins 2 and 3 to open the cover and pins and 3 to close it. The key switch does not require, and does not have, the ground connection. The remote control unit works the same way but it does need the ground connection. The new harness connects two Molex Mini-Fit 4-pin connectors (from the original controllers) to one 9-pin male D connector. 9

10 The Remote Control The manufacturer's remote control option is very expensive but any two-channel remote control can be used. We use a Quasar 6S2-433A, Maplin part number L27BK. Extra key fobs are Maplin part number RN56L. This unit was previously in use with the original controllers and is re-used unchanged in the new system. The receiver connects to the controller via a 4 core cable terminated with a 4-way Molex Mini-Fit connector, Molex part number The pins are Molex crimp socket terminals awg, Molex part number The pinout is as shown above for the key switch. The receiver unit is wired so that the Open button connects pins 2 and 3, and the Close button connects pins and 3. 0

11 The Relay Boxes The relays on the Arduino 8-channel Relay Module are rated at 0A, but under heavy load the motors can exceed that. The relays on the original controllers are rated at 30A. We also need to power the motors on each side from the local battery. The solution is to provide four additional 30A automotive relays on each side, and trigger these relays from the Arduino 8-channel Relay Module. It may seem an excessive use of relays, but it works well and keeps the high motor currents well away from the Arduino. The left and right relay boxes are identical. Each contains four standard 2 Volt 5 Pin 30 Amp automotive accessory relays with terminals numbered 85, 86, 87, 87a, & 30. The connections are made with standard automotive spade connectors. Where motor current is carried,.5mm2 flexible mains cable is used. The wiring is such that: If neither relay is energised, both motor terminals are connected to -ve, acting as a brake. If relay is energised, one motor terminal is +ve and one is -ve, so the motor runs. If relay 2 is energised, the motor terminal are -ve and +ve, so the motor runs the other way. If both relays were to be energised, both motor terminals would be connected to +ve, again acting as a brake. As with all relays, back EMF suppressor diodes are required to protect the control circuitry. These are fitted in the Control Box, although arguably it would be better to fit them in the Relay Boxes.

12 Cables The Relay Boxes each have three external cables: A 6-core cable about 50cm long terminated with a male D-sub-9 connector. This cable supplies 2 volts to the control box and receives relay switching signals from the control box. DB9 Pin Cable Colour Blue Yellow Green Brown White Grey Function Ground Move open Move close Lift up Lift down +2 volts to Control Box Relay Coil A 2-core.5mm2 power cable about 30cm long terminated with 6.3mm piggyback spade connectors. This cable picks up 2 volts from the local battery. A 4-core.5mm2 motor cable about 20cm long terminated with a female Molex connector, which connects to the original motor cables. The existing motor cables connect both motors on one side to a single 4-way Molex plug as follows: Pins & 3 drive the Move Motor When pin is +ve and pin 3 is -ve, the cover opens When pin is -ve and pin 3 is +ve, the cover closes Pins 2 & 4 drive the Lift Motor When pin 2 is +ve and pin 4 is -ve, the lift lifts When pin 2 is -ve and pin 4 is +ve, the lift lowers Note that the left and right lift motors must actually run in opposite directions. This is handled by the software. The left and right Relay Boxes are identical. The pins are connected to the relays as follows: Molex pin Relay, pin 30 2, pin 30 3, pin 30 4, pin 30 The relays are built into a plastic box about 50 x 80 x 50 mm. In the picture, a small piece of UPVC is used to hold the relays in place. Once the boxes have been tested, the cable hole is sealed with hot glue and the lid of the box is sealed with electrical tape. Automotive relays rarely fail and we don't expect to ever have to revisit these boxes. 2

13 3

14 The Manual Switch Box The Manual Switch Box is an optional extra, for use in an emergency if the Arduino system fails. It enables the 8 motor relays to be manually activated using four momentary SPDT switches. It's quite easy to open the cover using this system, but more difficult to close it because the sections must be moved forward to exactly the right position. The switch box terminates with two female 9-pin D connectors, which can quickly be connected on the left side in place of the Control Box. Each pair of switches takes 2 volts from pin 6 of the 9-pin D connector. The cable needs to have ten cores and be about 2 metres long. 4

15 The Charger Module We don't want mains power anywhere near the swimming pool, so a small DC mains adaptor is located in the pool shed, supplying 5 volts to the left motor housing. We use a 5 volt 500mA adaptor, much like the one supplied with the original system. The ideal float charge for a 2V Sealed Lead Acid Battery is between 3.6 and 3.8V. An LT29 variable voltage regulator salvaged from an original controller is used to derive the required charging voltage. With R = 68k and R2=80k, the output voltage is 3.7v. Since the LT29 dropout voltage is 400mv, the minimum input voltage required is 4.v. The LED requires a 0.5W 680R resistor. If you don't have 0.5W resistors, you can use two 0.25W.5k resistors in parallel. The Charger Module is built on a small piece of strip-board with no track breaks. The regulator is actually mounted vertically with a heatsink. The output has a cable about 60cm long with piggyback spade connectors that connect directly to the left battery. The batteries must be brought into the house for the winter if there is a possibility of frost, and should not be allowed to fall below 2.6 volts. The Charger Module can be left permanently connected to the batteries over the winter. 5

16 The Input Module The Input Module contains the following components: The 9 volt regulator for the Arduino. The 5 volt regulator for the 8-channel Relay Module The voltage divider for monitoring the battery voltage. The buzzer. The input sensor voltage dividers. Regulators and voltage monitoring The maximum supply voltage for the Arduino is 2 volts, but the lead acid batteries can reach 3.8 volts. To avoid stressing the Arduino, we provide a 9 volt supply from the batteries, using a 7809 fixed voltage regulator. The 8-channel Relay Board requires a 5 volt supply, which is provided by a 7805 fixed voltage regulator. A voltage divider reduces the 2 volt battery voltage so that it can be monitored by Arduino pin A5. R7 is 3.3k and R8 is k. Buzzer Output The buzzer is a Kingstate KXG22C from an original controller, providing a fixed 2.3kHz tone. They are specified as 2 volts, 30mA but provide an adequate beep at 5 volts drawing about 0mA, so can be directly connected to an Arduino output pin. The buzzer has to be connected the right way round. There is a round symbol marked on the casing next to the positive terminal, which goes to the Arduino I/O pin. Switch Inputs There are five switch inputs on the left side and three on the right. The three on the right side are connected via a cat5 cable running in the same conduit as the motor activation cables, and are severely affected by noise. The usual 5 volt sensing voltage with pull-up resistor did not work at all well, so we chose to make use of the local 2 volt battery to supply a 2 volt signal when the switches close, with a voltage divider to pass a suitable voltage to the Arduino pin. Even this arrangement suffered from noise without the inclusion of the 0.uF capacitor. With the capacitor, the circuit works perfectly. The same circuit is repeated eight times: 6

17 Key and Remote Control Input 7

18 Sensor Inputs Buzzer 8

19 Stripboard Layout The Input Module is built on a piece if strip-board about 50mm x 40mm. Track breaks are shown with a red dot. 2 volts is supplied from the motor relay connectors. 9

20 The Control Box An ABS plastic box about 8cm long x 2cm wide x 8cm deep houses the Arduino, the 8 channel Relay Module, and the Input Module. Five female 9 pin D connectors are mounted on the ends of the box. Ideally, you need at least 7 different colours of hookup wire. For example: Ground 2v 5v Raw sensor inputs Arduino sense inputs Arduino motor outputs Relay motor outputs Black Red Brown Yellow White Blue Orange Arduino Connections The Arduino Uno has just enough I/O pins: Arduino Pin D0 D D2 D3 D4 D5 D6 D7 D8 D9 D0 D D2 D3 A0 A A2 A3 A4 A5 Gnd Power 5v Function Arduino Serial Receive Arduino Serial Transmit Motor Output Left Down Motor Output Left Up Motor Output Left Close Motor Output Left Open Motor Output Right Down Motor Output Right Up Motor Output Right Close Motor Output Right Open Switch Input Left Fully Open Switch Input Left Fully Closed Switch Input Left Fully Lifted Arduino on-board LED & Buzzer Switch Input Right Fully Open Switch Input Right Fully Closed Switch Input Right Fully Lifted Switch Input key switch Open Switch Input key switch Close Battery voltage monitor Ground 9 volts from the Input Module (2.mm plug, centre +ve) Reference voltage 5 volts from the Input Module Connects To Not used Not used Relay Module IN Relay Module IN2 Relay Module IN3 Relay Module IN4 Relay Module IN5 Relay Module IN6 Relay Module IN7 Relay Module IN8 Input Module Input Module Input Module Input Module Input Module Input Module Input Module Input Module Input Module Input Module Relay Module GND Input Module Relay Module VCC Relay Module JD-VCC The 8-Channel Relay Module The Relay Module is a "SainSmart 8-Channel 5V Relay Module for Arduino". It needs three power supplies: VCC is the Arduino 5 volt supply used as a reference for the input pins. 20

21 The relay coils must be powered by a separate supply because the Arduino 5 volt supply is not powerful enough to power the relays. Remove the jumper between pins 2 (VCC) and 3 (JD-VCC), and connect the 5 volt supply from the Input Module to pin 3 (JD-VCC). The common terminals of the relays are all connected to 2 volts. The Normally Open relay terminals are connected to the motor DB9 connectors. N400 diodes are is used to protect the Control Box against the back EMF from the secondary relays. 2

22 The Arduino, Relay Module and Input Module connected and ready to go into the Control Box (the suppressor diodes are not installed yet!) The Completed Control Box 22

23 Construction All soldered pin connections should be protected by heat-shrink sleeving for mechanical and environmental protection. Where cables enter a D-sub-9 cover, they should also be protected with heat-shrink. Use a proper crimping tool to crimp the spade connectors and check every crimp for tightness. If you are likely to make mistakes, consider using a Ruggeduino instead of a standard Arduino. Use coloured tape to match connectors to help prevent possible misconnections. Parts List Some parts can be salvaged from the original controllers: The Molex 4.20mm Pitch Mini-Fit Jr. series connectors. The LT29 variable voltage regulators. The voltage regulator heatsinks. The Kingstate KXG22C buzzers. Most parts can be obtained in France from Relay Boxes (two) Plastic box about 50 x 80 x 50 mm 5 Pin automotive type 2volt 30Amp relays 6.3MM Female spade crimp connectors Male D-sub-9 connector D-sub-9 connector cover 6-core cable, about.5m 4-pin Molex connectors Conrad Conrad Conrad 7455 Conrad Conrad Conrad Original controller Charge Module LT29 adjustable output voltage regulator LT29 heatsink 68k 0.25W resistor 80k 0.25W resistor 0uF electrolytic capacitor LED 680R 0.5W resistor Original controller Original controller Input Module fixed voltage regulator 7805 fixed voltage regulator 3.3k 0.25W resistor k 0.25W resistor.8k 0.25W resistors 0.uF polyester capacitors Buzzer Conrad or Original controller Control Box 5 5 Plastic box about 75 x 25 x 00 mm Female D-sub-9 connectors D-9 locking screw kit Arduino Uno Conrad 5388 Conrad Conrad

24 8 SainSmart 8-Channel 5V Relay Module for Arduino N400 Diodes Arduino female headers Arduino male headers Cable Harnesses, Connectors, Miscellaneous pin Molex connectors 4-pin Molex connectors Male D-sub-9 connector Female D-sub-9 connectors D-sub-9 connector cover 6-core cable to go from one side to the other 6.3MM Spade crimp connectors, various gauges 6.3MM Piggyback spade connectors Various sizes of heatshrink sleeving Hookup wire in various colours Strip-board Original controller Original controller Conrad Conrad Conrad Conrad Conrad 7455, 74594, Conrad Conrad Conrad 60555, Control Box Cutout Templates Installing the Software To download the software into the Arduino, you need to connect the Arduino to a PC or Mac using an "A-B" USB printer cable. You also need to download and install the Arduino programming software from here: We maintain the pool cover control program as a stand-alone text file. Download the latest version of the pool cover control program from here: At the time of writing the latest version is "pool_cover_.04.c" Open the file in any text editor, copy the entire text, paste it into the Arduino Sketch window, and click the Upload button. The program will be uploaded to the Arduino and start to run. Start the Serial Monitor (Ctrl-Shift-M) at 57,600 baud to see diagnostic output and enter diagnostic commands. Testing the Relay Boxes If you built the Manual Switch Box, you can use it to test the relay boxes. If not you can use jumper wires on the D connector pins. Connect 2 volts to the Relay Box and activate each relay in turn and check that the correct voltages appear at the motor connector. Testing the Control Box The Control Box should be thoroughly tested before it is installed in the cover. Connect 2 volts to pins and 6 of one of the motor connectors, and connect a PC to the Arduino, and start the 24

25 Arduino Serial Monitor. You should see the "Initialised" message, followed by the value of the battery voltage. You can use the Serial Monitor to enter the following commands:? t lu ld lo lc ru rd ro rc bu bd bo bc s o c d e q v m Show the current state of all the switches Test all relays - switches all the relays on for 2 seconds Left Up Left Down Left Open Left Close Right Up Right Down Right Open Right Close Both Up Both Down Both Open Both Close Stop all motors Simulate the key being set to open the cover (stop with the "s" command) Simulate the key being set to close the cover (stop with the "s" command) Disable all motors - no motors can run until an "e" command is entered Enable - cancel the "disabled" state Quiet mode - disables the buzzer and battery warnings Show the current battery voltage Show the current memory usage The 8-way relay board has LED's that light when each relay is activated. The "t" command, as well as the individual "l" and "r" commands should be used to verify that all the relays are working correctly. A volt-meter should be used to check that the correct outputs are activated. A jumper wire should be used to inject 2 volts into each of the sensor inputs. As each switch is activated and de-activated, a message is shown on the Serial Monitor. The Control Box can also be bench tested in conjunction with the Relay Boxes, using the diagnostic commands to activate each relay in turn. 25

26 Installation Right Side Remove the original controller, together with its battery cables. Remove the old connectors from the end of the existing left-right 6-core cable and fit a 9 pin female D connector to it. Fit a 9 pin female D connector to the end of the new 4-core cable. Install a Relay Box and Sensor Harness. Connect both to the battery. The Completed Right Side Left Side Same as the right side, plus: Install the Charger Module and connect to the battery. Install the Control Box and Key Harness. Connect the key switch and remote to the Key Harness. The Completed Left Side 26

27 Commissioning If you built the Manual Switch Box, you can use it to test that the relay boxes correctly drive the motors. It is fairly easy to open the cover using the switches. It is also possible, but more difficult, to close it. The Control Box should initially be tested while connected to a PC. Open the Arduino software and start the Serial Monitor. You should see the "Initialised" message, followed by the battery voltage. The first job is to test all the switch inputs by manually activating each switch. As each switch changes, a message is displayed on the serial monitor. Each change should only output one message with no "bounce". The next job is to test each motor individually, using the diagnostic commands. When starting a motor individually, keep a finger on the "s" key, ready to stop it quickly. You don't want individual motors to run for very long. The commands must activate the correct motors. If they don't, you must change either the physical wiring, or the constant definitions in the program. Once the switches and motors have been checked individually, you can test the Open and Close functions. Opening should normally work without any problems, although the first time, keep a finger on the "d" key ready to stop and disable the motors quickly if something doesn't look right. Adjusting the Fully Closed Sensors Closing starts by advancing the first section until it hits the "fully closed" sensors. The next section is then lowered behind it in order to engage in the hooks of the next section. Since the timing of the Arduino system is different from the original controller, you will need to adjust the fully closed sensors. Be careful here as incorrect adjustments can cause damage. As the first section begins to lower, stop the motors just as lowering begins. Look carefully at both sides and measure the adjustment required. Each section should stop about 6-7 mm away from the one in front, on both sides. The "fully closed" sensors are triggered by movable stops on each side of each section, just below the drive track. The stop is secured in its track by a grub screw with a 2.5 mm Allen key head. Loosening the grub screw allows the stop to slide backwards and forwards in the track, although it may require a light tap with a tool to free it. Moving the stop forwards (towards the 27

28 pool) causes that side of that section to stop sooner. Moving the stop backwards causes the section to stop later. The stops must be adjusted so that when the next section is lowered it engages perfectly with the previous section. 2.5mm hex grub screw To make adjustments, measure how far forwards or backwards each stop needs to move, then briefly reverse the section so that the stops are accessible behind the move motors. Mark the current and new positions with a pencil before loosening the screw and tapping the stop to its new position. The process must be repeated for each section, and it can take some time to get every section set perfectly. It is important that each section lowers perfectly without skewing the previous section. Note that if the gap is more than about 5mm, when the next section lowers, it may be pulled forwards towards the previous section, and in extreme cases it may be pulled clear of both fully open sensors (the ones at the very back of the motor housings). This will "confuse" the controller program. It really is very important that the fully closed sensors are correctly adjusted. The control program waits for the left fully closed sensor to trigger before stopping the left move motor, and it waits for the right fully closed sensor to trigger before stopping the right move motor. If one side runs for more than a few seconds more than the other, the program beeps four times and stops. For the first section, this approach works well, allowing the adjustment of the stops to "steer" the cover on the correct path. The adjustment of the first section sets the closing alignment of the entire cover. For the rest of the sections it's not possible for the motors to steer the cover, so you must make sure than the left and right sensors are adjusted so that they both trigger. It's best to start with the first section and work backwards. 28

29 Normal Operation You may notice a short delay (600 milli-seconds) before the key begins to open or close the cover. After that, holding the key in the open or closed positions works as normal. However, if you turn the key to the Open position and off again 3 times within 4 seconds, the program beeps once, then enters "auto-open" mode, running 4 open cycles, then stops. The number of sections defaults to 4 but you can easily change it by changing the value of NUMBER_OF_SECTIONS, near the top of the program. The auto-open process can be stopped at any time by turning the key briefly in either direction. Doing a full open in automatic mode should not normally be a problem, but you should keep an eye on the process and be ready to stop it if necessary. Auto-close mode is invoked in the same way, but you must watch the process more carefully. If lowering fails to securely engage two sections properly, damage can occur when the cover next begins to move. Beep Codes One beep is used to indicate the start and end of an auto-open or auto-close. Three beeps mean the battery voltage is low. Three beeps followed by a long beep means that the battery voltage is too low to run. Four beeps indicates an error, for example opening a section is taking too long to open or close, and the program stops the motors to prevent any possible damage. Switching the key off and on resets the error and you can try again. If you really need to know what the problem is, connect a computer and start the Arduino serial monitor to see the diagnostic output. 29

30 A Few Maintenance Tips Wickes in the UK sells a silicone lubricant for lubricating plastic guttering. It is clear, waterproof, and doesn't turn into a sticky brown mess like normal grease. It is ideal for outside use and perfect for metal-to-metal, metal-to-plastic, and plastic-toplastic. A small amount on the sliding plastic surfaces makes the whole cover run much more smoothly and quietly. Don't forget the large plastic hooks that engage the cover sections, the axles of the guide wheels, and the axles of the small lift wheels. Make sure all the guide wheels turn freely. Conrad part number is perfect for any that need replacing. The various plastic shaft bearings in the motor housings can break. A little silicone lubricant once a year might help them last longer. We also use the silicone lubricant on the chains. We now bring the batteries and electronics indoors for the winter. Lead-acid batteries are permanently damaged by being discharged for any length of time so they must be re-charged monthly, or left on permanent charge. 30