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WebMite-based Watering System Controller By Geoff Graham This advanced Watering System Controller does it all. It can change the watering schedule depending on the seasons, check the weather forecast before watering and even alert you to a burst pipe or blocked sprinkler. Best of all, it is very easy to set up and use. W ateringsystemcontrollers, often known as reticulation or irrigation controllers, are notoriously difficult to program. They generally have a small LCD screen and an array of tiny buttons or switches to configure the watering schedule. Our Watering System Controller has no LCD or buttons; it is entirely set up and controlled via a web browser on your smartphone, tablet or computer. The web pages are easy to understand and provide everything you need to set it up. The key component is the WebMite, a Raspberry Pi Pico W microcontroller running the MMBasic programming language, starting on page 28 in this issue. Here it delivers the web pages, gets the time, date and weather from the internet and follows the watering schedule you have configured. The only other significant components in this design are a small power supply and the solid-state relays (SSRs) that drive the solenoid watering valves. The program running on the WebMite is written in BASIC, so you can read it and edit it if you have any special requirements. This project was partly developed to demonstrate what you can do with the WebMite. Even if you do not want to build a Watering System Controller, this project can be helpful by providing the code and techniques you can use in other projects. The Watering System Controller program will even run on a bare Raspberry Pi Pico W. That means you can explore the program and try it yourself without building anything; you just need the Pico W module. Watering system layout Fig.1 shows a typical reticulation layout. The water supply is connected via a master valve to a series of valves that control individual sprinklers (or sets of sprinklers). The Controller opens the master valve, then steps through each sprinkler valve in turn, opening them for the specified time. The master valve is important as it provides a backup if one of the sprinkler valves is stuck open (it happens). The master valve will still cut off the water supply, limiting the The finished controller in a weatherproof enclosure mounted on an exterior wall. We decided to mount the status LED on the lid along with a waterproof power switch. 34 damage caused by the permanently-open valve. Some systems have a pump as the water supply; in that case, the Watering System Controller would switch that on and off instead of a master valve. Either way, the Controller will switch it on half a second before the first sprinkler valve is opened and switch it off half a second after the last has been closed. That is to ensure that the water pipes leading to the sprinkler valves are kept full of water, avoiding the situation where a sprinkler valve closes after the master valve, letting water out of the pipes. Otherwise, when the master valve next opens, the water rushing through the empty pipes could act as a hammer and damage the joints in the pipe and the valve. The flow sensor is an optional but worthwhile addition. It is usually fitted at the outlet of the pump or master valve and tells the Controller the amount of water flowing through the system. The Controller records this and, over time, builds up an average flow rate for each valve. The Controller can then easily detect an abnormal flow rate when it opens a valve, either over or under the average. This is invaluable as an excessive flow indicates that a pipe has burst and it might be digging a hole in your garden. A lower-than-normal flow rate means a sprinkler or valve is blocked; if left unfixed, that could cause your plants to die. When an excessively high flow is found, the Controller immediately shuts off that valve to stop any damage. In the case of underflow, it will continue with the watering time in the hope that some water is getting Practical Electronics | August | 2024 Fig.1: a typical watering system layout. The water supply is connected via a master valve (or pump if using rain water) to a series of valves that control the sprinklers. The optional flow sensor allows the Controller to detect a burst pipe (above-average flow) or blocked valve (below-average flow). through, but it will also inform you of the problem. The rain sensor is also optional. The Watering System Controller can check the weather forecast for you and skip watering if rain is predicted, but connecting a rain sensor provides a backup specific to your garden. The Controller will check the sensor before it starts a watering run, and if it indicates that it is currently raining, the schedule will be skipped for that day. Typical Watering System Controllers require you to change the watering characteristics at the start of each season, and that can quickly become tedious, something that our design cleverly eliminates. That page includes buttons to configure each schedule. After clicking one, you will be presented with a web page similar to that shown in Screen 2, which provides all the schedule details. Controller capabilities To set up the Controller, you use a web browser to access its web page, shown in Screen 1. It lists all the possible watering schedules, with a button to configure each. It also has a RUN NOW button that can be used to start the watering schedule at any time. These schedules are set to start at a certain date in the year and terminate at another. For example, you can set up a schedule for the summer months tailored to the demands of hot weather, another for autumn when less watering is required, another for winter and so on. You can set up the watering requirements for the whole year and, unless you change your mind, it will be repeated year after year. Features & Specifications Practical Electronics | August | 2024 The first field on the configuration page allows you to enter a meaningful title to be displayed on the main page. You can also enable or disable the schedule with a checkbox. The next four fields let you set the start and stop dates in the year for the schedule. Schedules can overlap and, if you want the same watering scheme for the whole year, you can set the start to 1/1 and the end to 31/12. Configured using a web interface from a smartphone, tablet or computer Controls a master valve plus up to eight sprinkler valves Up to eight independent watering schedules Schedules can be customised for different requirements during summer etc The active schedule can be skipped if rain is forecast or detected Sprinkler times can be increased on hot days Flow sensor support for detecting burst pipes, blocked valves or sprinklers A rain sensor can be connected to avoid watering during rain Schedules can run on certain days of the week or at intervals in days Schedules can start at a fixed time or a period before/after sunrise/sunset Time and date are set from the internet with automatic daylight saving compensation » No battery-backed clock is required » Schedules continue if the WiFi or internet is down » Schedules automatically restart after a power failure » Powered by 24V AC at 1A » » » » » » » » » » » 35 The following section allows you to set the days of the week for watering or specify a watering interval in days. This is a case of one or the other but not both. Following this, you set the time for the watering to start. Screen 2 shows this set to 6 hours 0 minutes after midnight (ie, 6am). However, using the dropdown list, you can also specify a number of hours and minutes before sunrise, after sunrise, before sunset or after sunset. That gives you a lot of flexibility in setting the start time. In the next section, you can configure each solenoid valve’s watering time in minutes. The Controller will step through each valve in the sequence, opening it for the specified time. It can drive up to eight valves (plus the master valve), but you do not need to install that many if you need fewer. The program will skip any valves with a zero or blank watering time. If you have entered some watering times in these fields, the RUN NOW button will appear on the main page, even if the schedule is disabled and the other fields have not been filled in. That means you can create a watering sequence that can only be started on demand from the web page. The final section allows you to change the watering schedule for that day depending on the weather forecast. You can skip watering entirely if rain is forecast, and you can increase the watering times if the forecast for the next 24 hours predicts Screen 1: the main web page you see when you connect to the Controller. It lists all the watering schedules and their start and stop dates. The CONFIGURE button lets you change the associated schedule, while the RUN NOW button immediately starts that program. Screen 2: this allows you to modify a schedule, including the start and stop dates, the time to start watering, the watering time for each valve and the actions to take based on the weather forecast. 36 a maximum temperature over a certain threshold. The former can avoid wasting water, while the latter can prevent plant death on unusually hot days. At the bottom of the page is a button to save the changes that you have made. The BASIC program saves the configuration and settings to a file called “settings.dat” in the internal file system of the WebMite. On power-up or a reboot, the program reads that file so that all the details are in memory. General settings The GENERAL SETTINGS button at the bottom of the main page (in Screen 1) takes you to the web page shown in Screen 3. On this page, you can tell the program your location, connected sensors and details for sending emails. The location data is used for many features of the Controller, including its time zone, daylight saving compensation, the times for sunrise and sunset and the weather forecast. You need to enter the name of your city and the country code, which is AU for Australia and NZ for New Zealand (a full list of the Alpha-2 codes can be found at https://w.wiki/Gb$). After that, you can click on the TEST button, and you should see a response similar to that shown in Screen 4. For large cities, you can also enter a suburb (eg, “North Sydney”); if that is found, it will provide you with a more specific weather forecast. The database has over 200,000 cities and towns, so you should be able to find your location. If you cannot, try for the nearest larger city or town within the same time zone. The weather predictions might still be accurate enough, depending on how close it is to you. These functions use data from Open Weather Map (http:// openweathermap.­com). It uses that service to look up the latitude and longitude when validating your location. The program can then use that information to query Open Weather Map for your time zone (including DST) and the sunrise and sunset times. If a schedule depends on the weather forecast, the program will query Open Weather Map for the 24-hour forecast before running the watering schedule. With that data, the program can then determine if the schedule should be skipped or needs to be modified. If you do not enter a location, the Controller will still operate but will use the AEST (GMT + 10 hours) time Practical Electronics | August | 2024 Screen 3: this screen lets you change the settings for the Controller as a whole. You can tell it your location, the connected sensors and how to send emails. The location is particularly important as it is used to determine the time zone, daylight saving compensation, times for sunrise and sunset and the weather forecast. zone or whatever is set in the BASIC program. You can still set a watering schedule and start times, but compensation for daylight saving will not be included, and you will not be able to set times based on sunset/ sunrise or modify the schedule based on the weather. Sensors There is a section below the location data where you can configure the flow and/or rain sensors (if fitted). The flow sensor will alert you if the water flow for a particular valve is significantly over or under its average flow rate. Either case will cause the status LED to flash and add a warning message on the main web page of the Controller. However, these can be missed, so an email alert (see below) should also be configured to ensure you are notified of the fault. If the fault is not corrected, the Controller will, over time, add this abnormal flow into its average flow rate for the valve and eventually stop treating it as a failure. So, if you get an email indicating a fault, make sure that you attend to it. When you fix the fault, click the button to reset the average so that the BASIC program knows to build a new average for fault detection (it will do that for all valves). You can connect a rain sensor and, if configured, the Controller will not run a watering schedule if it is currently raining. That is in addition to checking the weather forecast. Most rain sensors have normally-closed contacts that open in the case of rain, which is what the Controller is designed for. You just need to connect it to the screw terminal on the Controller and tick the box to enable this function. Sending emails This is an invaluable feature as you would not normally check the Controller’s status LED or web page daily. Because sprinklers are usually run before sunrise, critical faults can remain unnoticed for months, by which time they could have done a lot of damage to your garden. To send emails, you need to open a free account with SendGrid (http:// sendgrid.com). Opening the account is a little tedious because they need to verify your identity to prevent spammers from abusing their service. However, with the account created, you can get a free API key (a 69-character string) that you can enter in the API key field. When you get the key from SendGrid, you must also provide them with a matching “from email address”, Practical Electronics | August | 2024 Screen 4: you can test the location you entered and if it is found, you will see a message like this. When you test the email function, you will see a similar message confirming that it worked OK. which should be entered in the next field (From Email Address). Finally, you need to provide an email address to receive emails. This can be the same as the From Address or different. To test your settings, click on the TEST button. After a few seconds, you should see a confirmation message telling you that a test email has been successfully sent. You can then check your email inbox to confirm you have received it. Circuit details The circuit diagram for the Watering System Controller, Fig.2, is dominated by the Raspberry Pi Pico W (ie, the WebMite). The only other significant components are the power supply and the solenoid drivers. All valves use a single common return connection. The Controller is designed for the typical solenoid valves used in domestic reticulation systems that are controlled by 24V AC. These solenoids usually draw a surge current of 350mA when energised, then drop to a holding current of about 220mA. An IXYS CPC1965 solid-state relay drives each valve. These switch on the zero crossing of the AC waveform, 37 so there are no problems with inductive kickback from the coils in the solenoid valves. These are controlled by an inbuilt LED that provides isolation between the input and output. The drive current for the LED is about 5mA (limited by the 470W resistor), which is well within the drive capability of the microcontroller’s digital outputs. Only two solenoid valves can be energised at once: the master and the currently open sprinkler valve. These are protected by separate PPTC (polymeric positive temperature coefficient) ‘fuses’, which increase in resistance if there is an excessive current through them, limiting the maximum current. When the fault is removed, they revert to regular operation. They protect against short circuits in a solenoid or the solenoid wiring. The power supply is a switching buck (step-down) regulator providing 5V DC to the WebMite and the flow sensor (if fitted). This comprises switching regulator REG1, inductor L1, diode D1, a feedback voltage divider that sets the output to 5V and a couple of bypass/filter capacitors. The power requirement of the Controller is modest at 60-100mA. However, the relatively high input voltage of around 34V DC from the rectified 24V AC would result in 3-4W of heat being generated by a linear regulator. In a sealed enclosure, that could lessen the life of the electrolytic capacitors. With the switching power supply, dissipation is less than 1W. The life of the electrolytic capacitors is a major consideration, as the Watering System Controller should ideally last for 10-20 years or more. For this reason, we have specified high-­voltage, high-temperature capacitors with higher capacitances than strictly necessary. Those factors together should extend the life of the capacitors considerably. 5V power to the WebMite is supplied via schottky diode D2. This is to isolate the Controller’s power supply from the USB 5V provided by your computer if you have plugged that Photo 1: The fully populated Watering System Controller PCB (shown smaller than actual size). Along the bottom edge are the screw terminals for the power input, the master valve plus eight sprinkler valves and the inputs for the optional flow and rain sensors. The board has plenty of space below the screw terminals to route the wires. 38 into the WebMite, letting you use the USB port to debug and test the software on the WebMite even while the Watering System is powered. The flow and rain sensor inputs are pulled up to 3.3V (from the Pico) by 3.3kW resistors and clamped to stay within the supply rails by pairs of schottky diodes. The diodes are for protection from miswiring, nearby lightning strikes etc. In both cases, the input is pulled to ground by the sensor, which is detected and processed by the WebMite’s BASIC program. There are two LEDs and two tactile switches mounted on the PCB. The red LED indicates the controller status; when it is solidly lit, the Controller is operating without fault. If it is flashing or off, that indicates a fault like an abnormal flow detected by the flow sensor, an inability to connect to the internet etc. The green LED illuminates when the Controller is running a watering cycle; the abort button below it can terminate this cycle. The reset switch will force the WebMite to reboot, which is useful if you are upgrading the firmware. Circuit board design The fully-populated Watering System Controller PCB is shown in Photo 1. This is intended to be mounted in a RITEC RP1285BF 186 × 146 × 75mm waterproof sealed enclosure. Altronics stocks this (Cat H0310F) and there are others of a similar size, some with a clear lid. Note the screw terminals along the bottom edge of the PCB. The first on the left is the 24V AC power input. While a capacity of 1A is specified, a source capable of providing 750mA or more should work OK. Further along the bottom are the outputs for driving the eight sprinkler valves plus one master valve. Also on the bottom edge are the inputs for the optional flow and rain sensors. The flow sensor should be a Hall effect type that can be powered by 5V DC. The parts list gives a typical example, although there are many other suppliers. The rain sensor does not need power and should be a type with normally-closed contacts; again, the parts list gives a typical example. The board has been designed so there is plenty of space between the screw terminals and the bottom of the case, allowing you to route the wires easily. On the top of the PCB, there is space for a small toroidal transformer that can be installed by a qualified Practical Electronics | August | 2024 Watering System Controller Fig.2: the Watering System Controller circuit is dominated by the Raspberry Pi Pico W (ie, the WebMite). The power supply at upper left is a switching design to reduce heat generation. The solenoid drivers on the right switch on the zerocrossing of the AC waveform to avoid inductive spikes from the solenoid valves. electrician if the Watering System Controller is to be permanently wired to a power circuit. Before you decide on the placement of the Controller, check that the WebMite can reach your WiFi network at that location. As described later, you can do this by loading the firmware onto the WebMite and powering it with a 5V USB power bank or portable computer. If you can call up its web page from that location, you are good to go. 24V AC power source 24V AC is the standard power supply for domestic watering system controllers and if you are replacing an Practical Electronics | August | 2024 existing controller, it might already be available. We mounted the prototype Watering System Controller next to the house fusebox, which had a mains GPO socket inside, then used a 24V AC plug pack to power the Controller. This is the best and most economical solution; suitable plug packs are inexpensive and easy to find. Typical examples are Jaycar MP3032 and Altronics M9379A. If you want to power the Controller from the mains, you will need a qualified electrician to run the cables and connect them to a power circuit. This is expensive, so we do not recommend it, but if you must, the PCB has space for a small toroidal transformer at the top, such as Jaycar Cat MT2112 or Vigortronix VTX-146030-212. The Controller does not have facilities for terminating and fusing the transformer primary as that would be done by the electrician. Construction The Controller is built on a 132 × 152mm double-sided PCB coded 15110231, with the components mounted as shown in Fig.3. It is available from the PE PCB Service Before you start, you need to decide what options you will include or exclude. The first is the number of 39 valves to control. Most reticulation schemes only need two, three or four sprinkler valves, but the Controller can control up to eight to accommodate large layouts. Most constructors will choose one of the options mentioned in the parts list: four, six or eight valves. The two sensor inputs are also optional. You can omit the associated components if you do not plan to install a rain or flow sensor. Still, you might want to fit them in case you decide to use them later. The two LEDs and tactile switches are also optional. They are helpful if you are fault-finding or setting up the Controller, but they will be of little use once the box is sealed. You could mount them on the front panel using waterproof LEDs and switches with flying leads, where they would be much more useful. We mounted a waterproof power switch and status LED on the front panel of our prototype. If you see the LED flashing, you can visit the Controller’s web page to determine the cause. All the components are throughhole types, so construction should be easy and there are no particular tricks. Follow Fig.3 and the silkscreened text on the PCB and start with the low profile components, working towards the taller components. The WebMite (Pico W) can be soldered directly to the PCB, but we strongly recommend using sockets on the PCB and pin headers on the WebMite to make it a plug-in device. That way, you can easily remove it for testing and fault-finding. Loading the firmware Before you plug the WebMite into the board, load the firmware via the USB port on a computer (Windows, Mac or Linux). Starting with a factory-­fresh Raspberry Pi Pico W, you first need to load the WebMite firmware (MMBasic). The process is described in detail in the WebMite User Manual, but we will summarise it here: 1. While holding down the white button on the top of the Pico, plug it into your computer. The Pico should appear as a pseudo USB drive on your computer. 2. Locate the WebMite firmware (with a name like WebMiteV5.07.07. uf2) and drag and drop that into the USB drive. 3. When it finishes copying, the WebMite will reboot and reconnect to your PC as a serial port over USB. The green LED on the top of the Pico W should slowly flash. 4. Determine the name of the serial port used by the WebMite (ie, COM12), then use Tera Term (http:// tera-term.en.lo4d.com) to connect to that port. Fig.3: this shows where to place the components on the PCB. Note that many parts are optional and could be left off if you don’t need them. Take care with the orientation of the IC, diodes, SSRs and electrolytic capacitors. 40 Practical Electronics | August | 2024 5. Press return/Enter and you should see the MMBasic command prompt (the > character). Next, you must set the WebMite options for accessing the WiFi network. These are entered at the command prompt and each will cause the WebMite to reboot, so you will need to reconnect the Tera Term session after each (the double quotes are required for the SSID and password values): OPTION WIFI “SSID”, “password” OPTION TCP SERVER PORT 80 OPTION TELNET CONSOLE ON The following command will show the IP address that your router has allocated to the WebMite: PRINT MM.INFO(IP ADDRESS) Now you need to copy some files to the WebMite’s internal file system. The best way to do this is by using TFTP on your computer. Follow these instructions for Windows: siliconchip.au/link/abmf The files are in the download for the Watering System Controller from the August 2024 page of the PE website: https://bit.ly/pe-downloads They are named “retic.bas”, “config.html”, “index.html” and “setup. html”. Use the following TFTP commands to transfer the files (ipaddr is the IP address of the WebMite): TFTP -i ipaddr PUT retic.bas TFTP -i ipaddr PUT config.html TFTP -i ipaddr PUT index.html TFTP -i ipaddr PUT setup.html You can check the files have copied correctly by using the command FILES at the MMBasic prompt. That will list the files in the internal file system. Now you can run the BASIC program using the following command and the Watering System Controller should start up: RUN “retic.bas” When the program starts, it will print a series of status messages on the console. The program does this whenever it takes some action; it is useful for debugging and understanding what is happening. You can now fire up your web browser and enter in the address field the IP address of the WebMite that you determined earlier. When you press Enter, you should then see a web page similar to Screen 1 (without the configuration data entered). Note that it’s possible to skip all the steps above apart from setting the WiFi options and running the program by instead loading the allin-one “WaterCtrl.uf2” file that’s Practical Electronics | August | 2024 Parts List – Watering System Controller 1 double-sided PCB coded 15110231, 132 × 152mm 1 Raspberry Pi Pico W microcontroller module (MOD1) 1 RITEC RP1285BF 186 × 146 × 75mm sealed enclosure [Altronics H0310F, DigiKey 164-RP1285BF-ND, Mouser 546-RP1285BF] 1 330μH 0.5A bobbin-style inductor (L1) [Altronics L6227] 1 IXYS CPC1966Y or CPC1965Y solid-state relay (SSRLYM) [Mouser 849-CPC1966Y or 849-CPC1965Y] 2 500mA hold current, 1A trip PPTC resettable fuses (PTC1-2) [Altronics R4550A or Bourns MF-RX050/72-AP] 2 PCB-mounting momentary tactile switches (S1, S2) [Altronics S1120] 2 two-way 5/5.08mm 45° PCB-mounting terminal blocks (CON1, CON2) [Altronics P2044A] 2 20-pin headers, 2.54mm pitch (for MOD1) 2 20-pin header sockets, 2.54mm pitch (for MOD1) 2 3AG PCB-mounting fuse clips (F1) [Altronics S5980] 1 3AG slow-blow 500mA fuse (F1) 4 No.4 × 6mm panhead self-tapping screws Semiconductors 1 LM2574(Y)N-ADJ buck regulator, DIP-8 (REG1) 1 W04 400V 1.2A bridge rectifier (BR1) [Altronics Z0073 or Z0073A] 2 1N5819 40V 1A schottky diodes (D1, D2) 1 3mm red LED (LED1) 1 3mm green LED (LED2) Capacitors 2 220μF 63V 105ºC radial electrolytic caps Resistors (all ¼W 5% axial) 1 10kW 1 3.3kW 3 470W Extra parts for a four-, six- or eight-valve controller 4, 6 or 8 IXYS CPC1966Y or CPC1965Y solid-state relays (SSRLY1-SSRLY8) [Mouser 849-CPC1966Y or 849-CPC1965Y] 4, 6 or 8 470W ¼W 5% axial resistors 2, 3 or 4 two-way 5/5.08mm 45° PCB-mounting terminal blocks (CON3-CON6) [Altronics P2044A] Extra parts for the flow sensor 2 1N5819 40V 1A schottky diodes (D3, D4) 1 10kW ¼W 5% axial resistor 1 3.3kW ¼W 5% axial resistor 1 three-way 5/5.08mm 45° PCB-mounting terminal block (CON7) [Altronics P2045A] 1 5V-powered flow sensor, TTL output [Valves Direct siliconchip.au/link/abmg] Extra parts for the rain sensor 2 1N5819 40V 1A schottky diodes (D5, D6) 1 10kW ¼W 5% axial resistor 1 3.3kW ¼W 5% axial resistor 1 two-way 5/5.08mm 45° PCB-mounting terminal block (CON8) [Altronics P2044A] 1 rain sensor with NC contacts [Valves Direct siliconchip.au/link/abmh] included in the download package. Now you can install the WebMite on the Controller PCB, place the Controller in its final location and attach the case lid. You can then set up the Controller as described earlier by accessing it via WiFi, configuring each watering schedule, completing the basic setup section to enter your location etc. Fault-finding If the Controller does not work as expected, first check the status LED. If it is off or flashing, that means a fault has been detected; if it is permanently illuminated, that means that everything is working correctly (as far as the program is concerned). While the Controller is starting up, the LED will turn off or flash for a while, but if it is still flashing after a minute or two, something is wrong. If the LED indicates an error, log into the Controller web page and check for a message in red at the bottom. This could be an incorrect configuration, inability to access the internet, excessive water flow 41 Modifying the BASIC program While the Controller is configured via its web pages, you can also change some minor settings by editing the BASIC program. To do this, use Telnet to connect to the WebMite’s console (eg, using Tera Term), then press CTRL-C to interrupt the running program. Enter EDIT at the command prompt to run the editor. Scrolling down, you will see part of the program labelled “User changeable constants”, as shown in code below. These are the parameters that you can easily change. The status LED will flash continuously if you have not entered a location on the general setup page. To avoid this, you can turn off the warning by setting DisableLocationWarning to 1 instead of 0. You might want to change the default time zone from AEST (+10 ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' ' User changeable constants ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' ‘ set this to 1 to disable the location warning Const DisableLocationWarning = 0 ‘ this is the default time zone if the location is not set Const DefaultTimeZone = 10.0 ‘ the % increase in flow rate to trigger a fault Const UpperFtolerance = 50 ‘ the % decrease in flow rate to trigger a fault Const LowerFtolerance = 50 ‘ % forecast % chance of rain required to skip a schedule Const RainThreshild = 90 ‘ API key for accessing Open Weather Map ‘ This key is shared between all users of this program and is ‘ limited to 60 queries/minute. This should not be a problem but ‘ you can easily get your own key and be inderpendent. To do this ‘ goto https://openweathermap.org/ and open a free account, then ‘ generate a key and replace the key below with your own key. Const OWMKey = "73cd207244614965fc5ca3646bdd10ab" hours). To do this, change the line CONST DefaultTimeZone = 10.0 to your time zone. For example, Adelaide is 9.5. Note that the program will not be able to correct for daylight saving in this case. The program will signal a fault from the flow sensor if the value is 50% above the long-term average. This can be changed by changing etc. When you correct this error, the message should vanish and the status LED will stop flashing. If you cannot log into the web page or the Controller appears dead, unplug the WebMite and plug it directly into the USB port on your computer. Then use Tera Term to access the serial-over-USB console to diagnose the problem. You might have to press CTRL-C to terminate the running program so you can access the MMBasic console. Try restarting the BASIC program with the command RUN “retic.bas”. As the program starts, you should see a series of messages in your terminal emulator describing the progress. The first will be concerned with connecting to your WiFi, then connecting to the internet, followed by more messages detailing the progress in getting your location and time zone from Open Weather Map. The success or failure of these should give you some pointers as to where to look. Typical problems that can trip you up include: ● Not programming the Pico W with the correct WebMite firmware. ● Incorrect SSID or password in the OPTION WIFI command. Photo 2: the Controller mounted in a waterproof sealed enclosure. This shows it with an onboard 24V mains transformer, but note that it must be installed by a qualified electrician who will terminate the primary and connect it to a suitable power circuit. 42 Practical Electronics | August | 2024 the entry Const UpperFtolerance = 50 to another value. For example, if you wanted the Controller to be much more sensitive to excessive flow, you could change the value to 20 (20%). Similarly, for the lower tolerance (reduction in flow), change the entry Lower­Ftolerance on the line below. We have registered an account with Open Weather Map and used the associated API key in the Watering System Controller program. Their free account provides us with everything we need. The only significant restriction is that users of the key are limited to 60 queries per minute or a million in a month. That means that all users of this program will be using the same API key, but that should be fine as it is unlikely for 60 users to all make a call in the same minute. However, you can get your own access key if you want to be independent. If you open an account with Open Weather Map, they will provide you with an API key. The key is a 32-character-long string of letters and numbers that acts like a password. To replace the key in the code, edit the program line starting with “Const OWMKey =”. When the program gets the weather forecast from Open Weather Map, the chance of rain is returned as a percentage, with 0 representing no chance of rain and 100 indicating certainty. If a schedule is configured to skip watering on a forecast of rain, the program will do this if the chance of rain is at least 90%. You can change this threshold to anything you want by changing the line “Const RainThreshild = 90”. For example, if you only want to skip watering if it is certain to rain, you can set the value to 100 (ie, 100% chance). ● Your router is not configured for WPA-PSK security and DHCP. ● Your router is blocking the WebMite from reaching the internet. ● You have not set the options correctly. Use OPTION LIST to check them. ● You have not copied the program files to the WebMite. Use the FILES command to check that all four files have been copied correctly and are not zero bytes. If the WebMite seems to operate fine while plugged into your computer but not in the enclosure, then it could be something as simple as a wire inside the controller box draped near the WebMite’s WiFi aerial, reducing its sensitivity. If the fault appears to be with the control board, you will have to revert to traditional fault-finding procedures like checking that the power supply is working correctly and 5V is on the VSYS pin of the WebMite. Also check the component values and examine your soldering in detail. Hopefully, your Watering System Controller will work the first time, and you can relax knowing that your plants will have all the water they need. For future software updates, check the Practical Electronics website or the author’s website at: http://geoffg. net/retic.html If you enjy using the WebMite then consider joining the Back Shed Forum (www.thebackshed.com/ forum/Microcontrollers), where many enthusiastic WebMite and MMBasic users are happy to help newcomers with advice and hints. Teach-In 8 CD-ROM Exploring the Arduino Reproduced by arrangement with SILICON CHIP magazine 2024. www.siliconchip.com.au EE FR -ROM CD ELECTRONICS TEACH-IN 8 FREE CD-ROM SOFTWARE FOR THE TEACH-IN 8 SERIES FROM THE PUBLISHERS OF This CD-ROM version of the exciting and popular Teach-In 8 series has been designed for electronics enthusiasts who want to get to grips with the inexpensive, immensely popular Arduino microcontroller, as well as coding enthusiasts who want to explore hardware and interfacing. Teach-In 8 provides a one-stop source of ideas and practical information. 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