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Make it with Micromite Phil Boyce – hands on with the mighty PIC-powered, BASIC microcontroller Part 47: A PicoMite Smart-light Controller – Part 2 L ast month, we introduced the concept of a Smart-light Controller specifically for controlling the Philips Hue range of lighting products. There are two main reasons for selecting the Philips Hue range – first, Philips provide documentation which explains how to interface to their hardware to control it with simple commands; and second, the quality and reliability of the Hue range is excellent (but noting it is more costly than most other manufacturers). The heart of any Philips Hue smarthome setup is the Hue Hub (see Fig.1). Philips have incorporated an API (application programming interface) into their Hub, which means it is possible to communicate with it using a standard Fig.1. The Philips Hue Hub is the heart of a Hue setup. When connected to your home network it acts as an ‘Internet gateway’, allowing you to use the Hue App to control all your Hue smart lights (and smart sockets) from anywhere with an Internet connection. 56 Fig.2. The Waveshare Pico-ResTouch-LCD-2.8 module is an ideal touchscreen for use in our Smart-light Controller. It connects directly with the PicoMite – no cables needed. It also has an onboard SD socket which may prove useful. web protocol (more on this later). For this to work, the Hue Hub needs to be plugged into your home network; and this is typically done by connecting it to your Wi-Fi router. The Hue Hub then appears as a device on your network, meaning it will have an IP address for communication purposes. Put simply, by sending specific commands via Wi-Fi to the Hue Hub API, we can let it know how we want to adjust the smart lights. The Hue Hub will then take care of the more complex Zigbee protocol that Philips uses to communicate directly with Hue smart lights (and other Hue accessories). If you already have one or more Hue products, you will most likely have also downloaded the Philips Hue App onto a smart phone or tablet. This App provides complete control of any Hue product in your setup, and it can do this because it sends the relevant commands via your Wi-Fi network directly to the Hub’s API. So, all our PicoMite Smart-light Controller needs to do is communicate with the Philips Hue Hub in a similar way to the Hue App; something which is well documented by Philips. Therefore, this month we explain how to prepare the Hue Hub so that we can communicate with it; plus, we will assemble a test circuit to ensure we can indeed control a Hue smart light. Let’s start by looking at what PicoMite hardware will be used in our Smart-light Controller. PicoMite hardware From a hardware point of view, our controller will comprise the following three elements: 1. ESP32 Wi-Fi module – provides communication ability with the Hue Hub via Wi-Fi 2. Touchscreen – for our graphical user interface (GUI) 3. PicoMite – the ‘brains’ of our controller. Last month, in Part 1 of this project, we covered how to upgrade the firmware inside an ESP32 so that we have access to all the relevant commands that will be used in our program code. As a brief reminder, we will be sending AT commands from the PicoMite to the ESP32 to control all aspects relating to Wi-Fi network communication with the Hue Hub. Remember to ensure the ESP32 firmware has been updated – as described in Part 46 – before connecting it up. For the Touchscreen, you can use any compatible one that you have at hand. Here, we will use the readily available Waveshare Pico-ResTouch-LCD-2.8 module (see Fig.2). This is an SPI touchscreen with an SD socket, which may prove useful. Practical Electronics | June | 2023 port on your computer. The LED on the Pico will blink slowly, indicating that the PicoMite firmware with MMBasic is now running. The Firmware update should take no more than a couple of minutes and will ensure you have access to the MMBASIC commands we will use in our final program code. Checking the test circuit With everything connected, the next step is to ensure that you have the relevant OPTIONs configured. The exact ones required will depend on the touchscreen that you use, but for the display module we’re using here (Waveshare PicoResTouch-LCD-2.8) the OPTIONs are: 1. Plug the Raspberry Pi Pico into your computer with a USB cable, while holding down the white BOOTSEL button on the Raspberry Pi Pico. The Pico should connect to your computer and create a virtual drive (as if you had plugged in a USB memory stick). This virtual drive will contain two files which you can ignore (but do not delete them!). 2. Copy firmware file PicoMiteV5.07.06. uf2 to this virtual drive. 3. When the copy is completed, the Pico will restart and create a virtual serial Practical Electronics | June | 2023 TX RX EN Now set the relevant O P T I O N s , remembering to calibrate the touchscreen if required (with the GUI CALIBRATE command). It is also worth performing a quick test of the touchscreen using the usual commands GUI TEST LCDPANEL and GUI TEST TOUCH. If it doesn’t work as expected, then quickly check that the touchscreen is inserted correctly into the Pico Expansion module, and then check the parameters used in ESP32 each of the OPTION commands (use OPTION LIST to display them). Correct any errors you see – you may need to use the OPTION…DISABLE command. Once the touchscreen is confirmed as working correctly, download and install the first test program – SmartLightController_Test1.txt – available for download from the June 2023 page of the PE website at: NC NC https://bit.ly/pe-downloads NC RST This simple test program will TX CS first attempt to connect to your Wi-Fi network, and then it will RX NC attempt to fetch the current date NC NC and time from an Internet time NC NC server (and display the date and NC 3V3 time on the touchscreen). However, GND GND before you RUN the program, you Wifi BLE click first need to modify two lines of code. These need to be changed so that the program code can send 3V3 0V GP0 GP1 your Wi-Fi network name (SSID) and your Wi-Fi password to the ESP32, which will then allow it Fig.4. Only four connections are needed to to connect to your Wi-Fi network. connect the ESP32 module to the PicoMite. Two To do this, go to the editor (EDIT) are for the 3V3 power supply (do not connect to and scroll down to the first two 5V!); and two for the serial Tx and Rx signals. IO0 It is a plug-and-play device that needs no cables to connect it to the PicoMite. For test purposes, we recommend plugging these three modules into a Pico Expansion module (see Fig.3). The PicoMite and the Touchscreen can be mounted directly onto the expansion module; however, for the ESP32 module, simply use four DuPont leads to connect it to the PicoMite – see Fig.4 for the relevant pin numbers. One more consideration at this stage is to ensure that you have the latest version of the PicoMite firmware installed on your PicoMite. Visit geoffg.net/picomite.html and scroll to the Downloads section at the bottom of the page to obtain the latest .uf2 file (at the time of writing it was PicoMiteV5.07.06.uf2). A zipped folder will be downloaded, so you will need to extract it after downloading; and the required .uf2 file will be one of several files contained within the extracted folder. Here’s a reminder of how to install the downloaded .uf2 file into the PicoMite using the following three steps: OPTION SYSTEM SPI GP10,GP11,GP12 OPTION CPUSPEED (KHz) 252000 OPTION LCDPANEL ST7789_320, LANDSCAPE,GP8,GP15,GP9,GP13 OPTION TOUCH GP16,GP17 OPTION SDCARD GP22 GND Fig.3. A Pico expansion module like the one shown here makes it much easier to assemble our test circuit. Just four female-female DuPont leads are needed to hook up the ESP32 module. lines of uncommented code in the SETUP section. Here you will see the two required string variables (SSID$ and PWD$) that need to be modified. Edit them to contain the SSID and the password of your Wi-Fi network. Once this is done, RUN the program and observe your terminal app’s screen to see what is happening. After a short while, the current date and time should be displayed on the touchscreen. If the date or time is clearly incorrect (for example, ‘Thu Jan 1 1970 01:00:10’), simply wait a short while and RUN the program again. Any errors observed on the terminal screen will likely be caused by an incorrect SSID or password being used. Also, do ensure that you have access to the Internet on your Wi-Fi network. If you don’t have Internet access, then the ESP32 will be able to connect to your Wi-Fi network (when the correct SSID and password are used), but it won’t be able to connect to an Internet time server to display the correct date and time. Note that it will not be a requirement to have Internet access for our Smartlight Controller as it will only need to communicate directly with the Hue Hub (which is simply a device on your home network). However, the likelihood is that you will also have Internet access, and hence this test program checks that too by linking to an Internet time server. 57 Fig.5. The Hue Hub is easy to install – just two leads connect to the rear of the Hub for power and to your network (ie, Wi-Fi router). It must be stressed that it is not important at this stage to understand how the code works – it is just being used for checking the test circuit. With a test circuit built and successfully checked, we can now turn our attention to the components in the Hue setup. 3. C onfigure the Hue Hub (as per instructions from Philips) 4. Install and configure at least one Hue smart light so we have something for our controller to control 5. Identify the IP address of the Hue Hub, and make it ‘Static’ so that we know the IP address that our controller will need to communicate with 6. Obtain a unique API key from the Hue Hub (required for security reasons to prevent hackers controlling our lights) 7. Get a list of smart light IDs from the Hue Hub so we can tell the Hue API which specific light ID we are controlling. Do not panic if any of these steps don’t make sense at this stage – the list above is just provided as an overview of what we will be discussing in the next few sections. By the end of this article, everything will become clear. 1. Install the Hue Hub This is a straightforward step. When you purchase a Hue Hub (around £50 if purchased by itself, or cheaper if purchased in a Hue kit), there are three main items in the box: the Hub (also referred to as a ‘Hue Bridge’), its power supply and a network lead. At the back of the Hue Hub you will see two sockets (Fig.5). First connect the Hue Hub to your Wi-Fi router with the supplied network lead, and then connect the power supply. The blue LEDs will start to turn on, and after a short while, all three on the top should be lit. These LEDs (from right-to-left) indicate Power, Wi-Fi connection, and Internet connection. That’s it, the Hue Hub is installed. We will configure it in Step 3 after the Hue App has been installed. To prepare the Hue components for receiving communication from our Smart-light Controller, complete the following steps: 1. Install the Hue Hub (on your network) 2. Install the Hue App (on a smart phone or tablet) If you already have a Hue setup (with a Hue Hub), then the first four steps can be skipped; however, if you’re just starting out with Hue, then all seven steps will need to be performed. Once the required steps have been completed and we have the relevant information, we will then be able to use our test circuit from above to check that we can indeed control one of the smart lights in the setup. Please note that without the IP address of the Hub, or the API key, or the relevant smart light ID, or the appropriate command instruction, our Smart-light Controller will not work. Fig.6. There are many Apps related to Hue. Be sure to download the official Philips Hue App. Fig.7. a) (left) To find the IP address of the Hub, select ‘My Hue System’ from the ‘Settings’ page in the Hue App; b) (top right) tap the ‘i’ icon; and c) (bottom right) The Hub’s IP address will then be displayed. Configuring the Hue system 58 2. Install the Hue App The Hue App is required to configure the Hue Hub; and is also used to add smart Practical Electronics | June | 2023 lights and other smart devices such as switches, buttons, sockets and movement sensors. It can also be used to control any device in your setup (ie, turn a light on or off), and is particularly useful for device control when you’re away from home. The Hue App is free and available for download from the Google Play Store (for Android devices) and from the App Store (for Apple iOS devices). Search for ‘Philips Hue’ and you will see many Apps available. Be sure to install the ‘Official Philips Hue app’ which is simply called ‘Philips Hue’ (see Fig.6). After a few seconds it will be installed. Next, open it, to configure the Hue Hub. 3. Configure the Hue Hub When the Hue App is run for the first time, it will want to search for a Hue Hub (although there are a few confirmation buttons you will need to press first). We will not go into stepby-step detail here as Philips have made the process pretty much idiot-proof from the App! You will essentially have to press the round button on top of the Hue Hub (when instructed to do so), and the App will automatically link to it. It will then want to run a software update for the Hue Hub – let this update complete and wait for the confirmation message showing that your Hue Bridge is up to date. The App will then go to the Home page from where you ‘add a room’ by clicking the three dots in the top-right corner (and select the option ‘Add a new Room or Zone’). By adding an appropriately named room you will have somewhere to place the smart light that we’ll be adding in the next step. I find the Hue App very intuitive, however, if you do struggle with adding a room, or with anything else regarding the Hue App, then turn to the Internet where there are many step-bystep videos and tutorials. 4. Install and Configure at least one Hue smart light To add a Hue smart light to the setup, you simply click the three dots in the top-right corner of the Home page and select ‘Add lights’. You will then see an option to ‘Search’, but before you do this you must ensure the Hue smart light is installed in the light fitting and that it has power too – this means the smart light will initially be turned on. Upon pressing the Search button, the App will look for your new smart light, and after a few seconds, will display it in the App. Note that if you purchased a Hue kit, then the lights may already be shown in the App, meaning you can bypass the Search function. Once the smart light is listed in the App, you can rename it to something meaningful (eg, ‘Lounge Table Light’) and then you can associate it to a specific room (by dragging the light into the room). Now place your smart light in the room you created in Step 3. And that is it, the smart light is successfully added. Note that there is no need to configure any other item (such as a light switch to control the smart light we’ve just added) since the minimum requirement for testing our PicoMite controller is just a single smart light. From the Home page, you will now see the room that you just created. To the right, you will see a ‘slide switch’ which when tapped, will toggle the smart light between being turned on and turned off. Check that this does work. The above four steps are just standard Hue setup procedures. By using the App to add new rooms and new lights, you can expand on the number of smart lights in your home. 5. Identify the Hub’s IP address The Hue Hub is connected to your local network, and to communicate with it we will need to know its IP address. This is easy to find from within the Hue App; however, we ideally want to make it ‘static’ too so that it doesn’t change. That way, our PicoMite controller will always communicate to a single known IP address that remains the same. First, let’s find the current IP address by using the ‘Settings’ page in the App (bottom right-hand option), and selecting ‘My Hue System’ near the top of the list (Fig.7a). You will then see a ‘Philips hue’ option with an ‘i’ icon on the right-hand side (Fig.7b). On tapping the ‘i’, it will display information relating to the Hue Hub, including the IP address (Fig.7c). Make a note of this IP address and keep it at hand – we will need it for the following steps. Next, make this a static IP address. From the Settings page, scroll down to ‘Hue Bridge settings’ (Fig.8a). Select ‘Network settings’ (Fig.8b), then tap the DHCP switch (Fig.8c) so that it is off. Here you can set the IP address obtained above (it will likely Fig.8. a) (left) To make the IP address static, select ‘Hue Bridge settings’ from the ‘Settings’ page; b) (middle top) then select ‘Network settings’; c) (middle bottom) DHCP will be on; d) (right) and tapping it will turn it off where the IP address will be displayed. Practical Electronics | June | 2023 59 Fig.9. a) (top left) After installing Postman, you will see a screen inviting you to create an account, b) (top right) Select ‘Skip to go to the app’ to see the ‘Overview’ tab; c) (bottom) Select ‘Create a request’ and then you will be able to enter in an API request. be set already) – see Fig.8d. The point is to make sure DHCP is switched off so that the Hub’s IP address doesn’t change. 6. Obtain a unique API key Without an API key, we will not be able to communicate with the Hue API to control any smart lights. A unique API key is issued by the Hue Hub, and it is only issued when a request is sent to the Hub (a request only needs to be performed once). To be able to send the request to the Hub, we will need to send a basic command to the Hub (that doesn’t require an API key) using a piece of computer software that is able to send APIs. If this is starting to sound complicated – don’t panic. We will simply be downloading a program called ‘Postman’ which will allow us to send a message from our computer to the Hue Hub, and get a response back from the Hub. For example, we can send a request for an API key, and get a response back containing the unique API key number. For anyone experienced with APIs, you may already have an API tester that you can use instead of Postman. To download Postman, visit postman. com/downloads and follow the instructions. Once installed, run it and you will see a screen that resembles something like that shown in Fig.9a. Click ‘Skip….’ to see the ‘Overview’ tab Fig.10. When sending the request to get an API key, the Postman screen should look something like this. The response from the Hub is indicating that the Hub’s round button needs to be pressed. Note the Status showing ‘Status: 200 OK’. Any other value means something is wrong! 60 Practical Electronics | June | 2023 This time it will respond with two bits of information, as shown in Fig.11. Rather bizarrely, the API key that we need is the value returned for the ‘username’ (and not the ‘clientkey’) so be very careful to make a note of the ‘username’ for our API key. With this noted, we are ready for the next step. 7. Get a list of smart light IDs Fig.11. Once the Hub’s link button is pressed, if we send the same request again, this time it will respond with the required API key (for security reasons, it is shown here partially greyed out!). Note that the required API key number is in the ‘username’, and NOT in the ‘clientkey’. (Fig9b) and then select ‘Create a request’. This will take you to the screen where you enter the API request (Fig.9c). To send the request for an API key, change ‘GET’ to ‘POST’, and in the ‘Enter Request URL’ input box, type the following (but using the IP address of you Hub obtained in step 5): https://192.168.50.107/api Next, select the ‘Body’ tab (under the ‘Request URL’ just entered), and below that, select ‘RAW’. This will allow the request to be entered in the box. The request we want to send is: {"devicetype":"app_name#instance_name", "generateclientkey":true} Once this is entered, press the blue ‘Send’ button near the top-right of the screen. If everything is entered correctly, the request will be sent to the Hub at the IP address entered, and the Hub will send a response that can be seen towards the bottom of the screen. Refer to Fig.10 as to how the screen should look for this step. Looking at the response, you will see that it contains the words: "description": "link button not pressed" Press the round button on top of the Hub, and then resend the same request again. We will now use Postman again to send another request. We can simply edit the request we just used to get the API but ensure your make the following changes. The Request URL needs to be set to the following (but using your Hub’s IP address): https://192.168.50.107/clip/v2/resource/light Next, change ‘POST’ back to ‘GET’, and then select the ‘Headers’ tab underneath (rather than the ‘Body’ tab). Here we need to enter our API key as follows. In the ‘Key’ input box, type hue-application-key and in the ‘Value’ input box, type in your API key generated from Step 6. You then press the ‘Send’ button to send the request. Your screen should then look similar to that shown in Fig.12, but with a response that lists data from your setup. The bit of data we’re interested in is the first "id" value under the "data" heading (as highlighted in Fig.12). This is the smart light ID we that we will require for testing our PicoMite controller, so make a careful note of it. If you are lucky enough to have more than one smart light, then scroll through the response until you reach the required light you wish to control. If you noticed from Fig.12, the second line from the bottom of the screen-shot response shows the "name" as "Dining Room Light" so you can use this as a reference to the different lights. Test to control a single smart light With all the above steps completed, it is now time to see if we can control a smart light with our PicoMite controller test circuit. Download the file SLC_Test2.txt and load it into your PicoMite. Before running the code, you will need to edit the first three lines of uncommented code so that it knows the following three things: Fig.12. Here we can see how the request (and response) appear in Postman when obtaining a list of smart light IDs. Practical Electronics | June | 2023 61 • Your Hub’s IP address (Step 5) • Your unique API key (Step 6) • The Light ID (step 7) for the single smart light which we want to control. Note that when you used the initial Test1 program (to check the test circuit), you edited the first two lines to define your Wi-Fi network name (SSID) and Wi-Fi password. A specific AT command that was used in that program (AT+CWJAP) stores this network information in the ESP32’s internal Flash memory. Hence, we don’t need to define it again in this second test program. So, an important point to stress here is that you must ensure that you have RUN the SmartLightController_Test1 program (on the same Wi-Fi network) prior to using the SLC_ Test2 program code. For those who are inquisitive, whenever you power up the ESP32 having successfully complete Test 1, the ESP32 will automatically attempt to connect to the Wi-Fi network name which is stored in its Flash memory. This only takes a couple of seconds after powering up the ESP32 module, and if it does successfully connect, the ESP will respond on its Tx serial output with the message: WIFI CONNECTED WIFI GOT IP Back to SLC_Test2, go ahead and EDIT the program code to enter your Hub’s IP address, your API key and the required Light ID you wish to control. On running the program, nothing will appear to be happening, but you will observe a simple graphic on the touchscreen display. If you now tap the righthand side of the touchscreen, your smart light should turn on; and tapping the left-hand side of the touchscreen should GET T LATES HE T COP Y OF TEACH OUR -IN SE RIES A VAILAB L NOW! E turn it off. If this is what you observe, then congratulations, you have everything configured correctly. If Test2 does not control the smart light, then carefully check that the three lines at the start of the program code have the data entered 100% correctly. Any single character missed (or that is incorrect) will result in it not working. The code has been used on several different Hue setups at different locations (and hence on different Wi-Fi networks too), and the only time it failed was when I incorrectly entered a light ID into the program code. As always, reach out by email if you find you are struggling; but do ensure that you have methodically followed all the steps in the sequence presented in this article, without missing any of them out. Once again, understanding how the program code works is not important at this stage. Test2 is all about ensuring we have the correct API key, and that you understand how to extract a smart light ID. However, do feel free to have a play and see if you can modify the code and control a second smart light. Next time Now that we have everything in place to be able to successfully communicate with the Hue Hub, we are ready to work on the program code. In Part 3 of our Smart-light Controller project we will discuss how to implement the features we wish to add, such as selecting a specific light from a list of available lights, and how to control it – turning it on/off, or adjusting brightness. Until then, stay safe, and have FUN! Questions? Please email Phil at: contactus<at>micromite.org Order direct from Electron Publishing PRICE £8.99 (includes P&P to UK if ordered direct from us) EE FR -ROM CD ELECTRONICS TEACH-IN 9 £8.99 FROM THE PUBLISHERS OF GET TESTING! Electronic test equipment and measuring techniques, plus eight projects to build FREE CD-ROM TWO TEACH -INs FOR THE PRICE OF ONE • Multimeters and a multimeter checker • Oscilloscopes plus a scope calibrator • AC Millivoltmeters with a range extender • Digital measurements plus a logic probe • Frequency measurements and a signal generator • Component measurements plus a semiconductor junction tester PIC n’ Mix Including Practical Digital Signal Processing PLUS... YOUR GUIDE TO THE BBC MICROBIT Teach-In 9 – Get Testing! Teach-In 9 A LOW-COST ARM-BASED SINGLE-BOARD COMPUTER Get Testing Three Microchip PICkit 4 Debugger Guides Files for: PIC n’ Mix PLUS Teach-In 2 -Using PIC Microcontrollers. In PDF format This series of articles provides a broad-based introduction to choosing and using a wide range of test gear, how to get the best out of each item and the pitfalls to avoid. It provides hints and tips on using, and – just as importantly – interpreting the results that you get. The series deals with familiar test gear as well as equipment designed for more specialised applications. The articles have been designed to have the broadest possible appeal and are applicable to all branches of electronics. The series crosses the boundaries of analogue and digital electronics with applications that span the full range of electronics – from a single-stage transistor amplifier to the most sophisticated microcontroller system. There really is something for everyone! Each part includes a simple but useful practical test gear project that will build into a handy gadget that will either extend the features, ranges and usability of an existing item of test equipment or that will serve as a stand-alone instrument. We’ve kept the cost of these projects as low as possible, and most of them can be built for less than £10 (including components, enclosure and circuit board). © 2018 Wimborne Publishing Ltd. www.epemag.com Teach In 9 Cover.indd 1 01/08/2018 19:56 PLUS! You will receive the software for the PIC n’ Mix series of articles and the full Teach-In 2 book – Using PIC Microcontrollers – A practical introduction – in PDF format. Also included are Microchip’s MPLAB ICD 4 In-Circuit Debugger User’s Guide; MPLAB PICkit 4 In-Circuit Debugger Quick Start Guide; and MPLAB PICkit4 Debugger User’s Guide. ORDER YOUR COPY TODAY: www.electronpublishing.com 62 Practical Electronics | June | 2023