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26 Silicon Chip R l e ix E L B G Ne o P G iven the popularity of my RGB LED ‘Analog’ clock design, and with some possible upgrades in mind, I felt a follow-up was worthwhile. While this new whitefaced clock doesn’t necessarily make the previous black one obsolete, it has some nice new features. I explained in the earlier article (May 2025; siliconchip.au/Article/18126) that I used standard RGB LEDs rather than addressable WS2812B ‘NeoPixel’ LEDs as they’re cheaper and easier to solder. I have since discovered cheaper ways to get these parts while designing the RGB LED Star (December 2025; siliconchip.au/Article/19372). That project used pre-soldered SMD LEDs, so we’re using them again. That means the Clock kit comes almost fully assembled. You just need to add a few bits like the Raspberry Pi Pico W that controls it, and away you go! You can see a video of the new Clock starting up and showing the time using Wi-Fi/NTP at siliconchip.au/Video/ NewRGBClock Using addressable LEDs means that we can have some more interesting effects on this clock. The previous one was limited to lighting four or five LEDs at a time as it used multiplexing; any more and they would become too dim. This one doesn’t have such a restriction. So, for example, the optional ‘sub-second’ chaser that runs around the face each second can have a trail. Having onboard Wi-Fi gives built-in support for network (NTP) time, meaning it will work and remain accurate anywhere you can get an internet connection. It also means you can fully control and configure the Clock from a computer, tablet or smartphone. That’s far more convenient than fiddling around with buttons. There’s also a lot of status and debugging information available over that interface, which opens in a normal web browser. You connect the Clock to a Wi-Fi network by powering it up, connecting to the hotspot it creates, then choosing your network and entering the password. As soon as it’s connected, it will try to get NTP time, and it should display an accurate time almost immediately. You just need to set your time zone if you aren’t in NSW, Victoria, Tasmania or the ACT to get the correct local time year-round. Our last RGB LED ‘Analog’ clock was popular. This one brings some style changes and updated features. It uses addressable RGB LEDs, with built-in Wi-Fi and NTP support, so you don’t need to add anything for timekeeping. It can also use a GNSS/GPS module as a time source. Australia's electronics magazine siliconchip.com.au ED ‘Ana Par t 1b yN ic V las l ho C l og ’ i ne n ock If you connect a GNSS/GPS module, you can choose whether the clock uses NTP or GNSS as the primary time source. It can fall back to the other source if the signal is poor or unavailable. If using a GNSS module as the primary time source, it can operate in Wi-Fi access point mode, so you can still configure and control it using a wireless device even if no Wi-Fi access point is available. Since the LEDs are fully addressable, you have more choices of colours. The previous clock let you use red, green or blue for the hour, minute and second hands. This one lets you choose any available RGB colour and brightness for any hand, plus the sub-second trail (if enabled) and the AM/PM LEDs, which can be disabled if you don’t want them. You can easily adjust the brightness remotely, or activate/deactivate and configure automatic brightness using the onboard LDR light sensor. The clock can be powered from a regular USB 5V supply or via a higher-­ voltage DC supply, up to 15V, using an efficient onboard regulator. The firmware we supply should do all this and more, but if a bug is discovered, a future update is released, or you want to try changing some of its features, the firmware can be updated remotely, over Wi-Fi. Still, for the most part, once the clock is set up, you can just hang it on your wall, power it up and leave it. It’ll keep the time accurate and correct year-round. Circuit details As you can see from Fig.1, there isn’t a great deal to the circuit, as most of the complexity is in the Pico W software. The 60 WS2812B addressable RGB LEDs are partially shown at lower left. They are connected in series, and the Pico W feeds them data in a daisy-chain serial fashion from its pin 6 (GP4) digital output via a 330W resistor. That resistor dampens any inductive spikes from the tracks between the Pico and LEDs, so LED1 isn’t damaged. There are numerous 5V supply bypass capacitors spread around the board: 22 × 100nF ceramic, 8 × 22μF ceramic and 4 × 220μF solid tantalum. These ensure that the WS2812B supplies remain steady even if many of them are switching on/off at the same time. siliconchip.com.au Australia's electronics magazine November 2026  27 they sit at +3.3V when the corresponding button is not pressed or 0V when it is. The Pico W just has to read the digital input state and perform some software debouncing to sense when a button is pressed. The optional GNSS module interface is a row of six pads labelled CON2. A typical GNSS/GPS module will run from a 5V supply and offer a 3.3V TTL serial interface, which makes it suitable for direct connection to the Pico W pins. A 330W series resistor on GP13, the serial output, provides protection in case that pin is accidentally shorted to ground or +5V. A 10kW pull-up resistor on the serial input pin, GP12, means that if nothing is connected to CON2, the Pico W doesn’t receive noise or garbage serial data. Pin 16 will be clamped below about 4V due to its internal ESD proWhat this RGB LED tection diode. Clock can do: While a 1PPS connection is proTells the time using 60 addressable RGB LEDs vided (to digital input GP10), it and two optional AM/PM LEDs isn’t used by the firmware. The White clock face with black writing software could be changed to Built-in Wi-Fi time (NTP) support The AM and PM use it, but we found it was Easy-to-build kit available with most components pre-soldered LEDs (LED61 & LED62) fine to just wait for a serial Each ‘hand’ can be configured with its own colour and style are driven similarly but from time update from the mod(as can AM/PM LEDs) different outputs and via ule before updating the Optional sub-second hand chaser, which can be customised their own resistors – output clock display. Second hand can be switched off GP5 for LED61 and GP28 Digital output GP14 Automatic brightness via LDR (can be configured/disabled) for LED62. That is purely drives an active-high Can run from USB 5V or 6-15V DC via an onboard DC/DC converter to improve the PCB layout; enable output. This is GPS/GNSS module can be used as a primary or secondary time source those two LEDs are close to simply driven high when Configurable time zone settings with automatic changeover the Pico W in the middle, GNSS time is enabled in Two configurable buttons for various functions while LED1-LED60 are around the configuration, or low All settings are adjustable over Wi-Fi using a web browser the circumference of the board. the rest of the time. Initial SSID/password setup via a Wi-Fi hotspot generated by So a track from LED60 to LED61 the Clock Power supply would be much longer than one Over-the-air firmware updates using a web browser from MOD1 to LED61. The rest of the circuit is Wi-Fi status page, full configuration and The LDR for auto-dimming is conthe optional power logging/debugging features nected in series with a 100kW resistor supply. I write to form a divider so that the ambient optional light brightness is translated to a voltage at pin 31 of the Pico W, which is an analog input. The Pico W uses its internal analog-to-digital converter (ADC) to convert that voltage to a number that can be used to adjust the LED brightness. The top of this divider (one end of the LDR) is fed from pin 35, which is the ADC voltage reference pin, meaning that supply voltage variations won’t affect this reading. It becomes a pure reading of the relative resistance of the LDR to the fixed 100kW resistor. Pushbutton switches connect between digital inputs GP15/GP16 and ground. These inputs are configured with weak pull-up currents, so 28 Silicon Chip Australia's electronics magazine siliconchip.com.au Fig.1: the Clock circuit is dominated by the 62 addressable LEDs (only some of which are shown) and the Pico W module, MOD1. The power supply at the top is optional; it can run from 5V USB power via the Pico W’s onboard socket if desired. because you can power the whole clock through a USB cable plugged into MOD1. That’s what we did during development, and it worked fine. Still, if you want to run it from a battery or a plugpack, an efficient switchmode power supply is provided. 6-15V DC is applied to CON1, and Mosfet Q1 provides reverse polarity protection as it will only connect the negative input to GND if the positive input has a higher voltage. The incoming supply is filtered and fed through a ferrite bead (for EMI suppression) to REG1, a switching buck step-down regulator. Its output is filtered by inductor L1 and some more capacitors, and a divided version is fed back to its FB pin to obtain a regulated +5V at the output. This goes through another ferrite bead and feeds the +5V rail if LK1 is shorted. LK1 is a closely spaced pair of pads siliconchip.com.au on the PCB, so you just need to short them if you want to power the circuit through REG1. This has the advantage that you can check REG1 is working before applying power to the 62 LEDs. That way, if something is wrong and the output voltage is too high, you won’t cook them! The Pico W is powered by +5V at its pin 39 VSYS input. It internally regulates this down to 3.3V to power the microcontroller, flash memory chip and other onboard parts. Construction The Clock is built on a double-sided white PCB coded 19101252 that’s circular and close to 200mm in diameter. Our kit includes a mostly assembled circuit board plus the remaining parts. We have done it this way partly to make it easier for constructors, but also because the cost of doing it this Australia's electronics magazine way is not much higher than simply providing all the parts. Fig.2 shows the front-side overlay. The parts mounted on this side are 62 WS2812B LEDs, two small tactile pushbuttons and a through-hole LDR (light-dependent resistor). Everything else is on the back. The only part you’ll need to fit on this side is the LDR, but don’t do that yet. Fig.3 is the back overlay. All the capacitors and resistors will already be populated, along with some of the semiconductors. The only parts you need to add are MOD1, REG1 and CON1 (if you’re using them) plus the optional GNSS/GPS module. If using that module, it can be stuck on the back with double-sided tape (antenna facing out) and its cable ends soldered to CON2. There are also pads to solder a few stiff pieces of wire so it can hang on a wall without the electronic parts November 2026  29 touching the wall, if that’s how you want to display it. Setting up the Pico W Before you start soldering the components, there are a few things to do. One is to program the Pico W. That is easy as long as you have a computer and a USB cable with a micro Type-B plug at one end. Download the firmware from siliconchip.au/Shop/6/3662 and extract the UF2 file from the ZIP. Uploading the firmware is basically the same procedure as copying a file to a USB flash drive. Plug the Pico W into your computer and its ‘flash drive’ should appear, named “RPI-RP2”. Copy the UF2 file you extracted earlier onto that drive, and after a few seconds, it will disappear. A little later, the LED on the Pico W should start flashing at about 0.5Hz. That means the firmware was loaded correctly. If the ‘drive’ doesn’t appear when you plug the Pico W into your computer, unplug it and hold down the white BOOTSEL button while plugging it back in. Once the firmware is loaded, it’s a good idea to get it connected to your Wi-Fi network. That way you know the Wi-Fi is working before you solder it. If you plan to use a GNSS module only for time then you don’t need to connect it to your network, but you may want to do that anyway to make changing settings easier. The alternative is to let it create its Fig.2: there are 62 LEDs on the front of the board, two buttons, the LDR and printed labels. The copper is covered with a white solder mask to match the white LED bodies. 30 Silicon Chip own Wi-Fi network that you can join only when you want to configure or communicate with it. In that case, it would be a good idea to at least check that you can connect to it before soldering. Using a computer, smartphone or tablet with Wi-Fi, search for the network named “RGBClock”. By default, there is no security, so you should be able to connect to it without entering a password. Open up a web browser and go to http://sc-rgb-clock.local – you should see a screen similar to that shown in Screen 1. If that doesn’t work, try http:// 192.168.4.1 (sometimes the name resolution can be slow or unreliable but it should work eventually). Note that the package orientation marking for the WS2812B LEDs is located on pin 3, rather than pin 1 Australia's electronics magazine siliconchip.com.au If you’ve gotten this far, the Pico W and its firmware are definitely working, and if you don’t plan to connect the Pico W to your Wi-Fi network (meaning you can’t use NTP mode), you can unplug it now and finish assembly. Assuming you do want to use NTP mode, or at least have the convenience of accessing it through your network, you might as well set it up now. If you know the SSID and password for your Wi-Fi network, enter them in the fields at the top of the web page that you’ve opened. You can also change the hostname (the name you use to access the Clock) if you want. Change the network mode to “Connect to network”, then click Reconnect. If you don’t know the network SSID, instead click on the “Scan for networks” button in the Wi-Fi section. A new window should open, and after a few seconds, it will be populated with networks. Click on the one you want to connect to. This will fill in the SSID field and take you to the password field, where you enter your network password, then click Reconnect. You can connect your computer back to your normal Wi-Fi network and access the Clock’s page via http:// sc-rgb-clock.local Now that you know the Wi-Fi settings are now correct, scroll down to the bottom of that page and click the Save button to save these new settings to flash. You can make more changes later. You are now ready to unplug the Pico W and finish assembly. Mounting the Pico W The Pico W can be surface-mounted onto the back of the clock PCB to make the clock as thin as possible. However, it’s unlikely you will be able to plug a USB cable into its socket if you do that. So if you are planning to power it from a USB cable, or want to debug it or upload new firmware via USB, you will need to mount it on some headers. Having said that, you can power it from a USB supply via CON1 if you need to, and it’s possible to update the firmware over Wi-Fi, so you can certainly use the clock with the USB Fig.3: on this side of the board, we have all the bypass capacitors for the LEDs, the Pico W control module, power supply and ancillaries. siliconchip.com.au Australia's electronics magazine November 2026  31 Screen 1: the RGB Clock can be controlled over Wi-Fi. Initially when connecting to it via http:// sc-rgb-clock. local you should see this screen. The Clock can also be configured using USB, as described in the panel overleaf. 32 Silicon Chip Australia's electronics magazine socket inaccessible. In that case, you will need to fit the REG1 chip later, or link it out if you’re going to run the clock from a source of regulated 5V DC (more on that later). Low-profile headers are tall enough to let a USB cable plug into the Pico W without making the clock assembly too deep, although you can use standard headers if you want. We supply low-profile headers in the kit, so you might as well use them. Start by soldering them to the Pico W module, inserted from the underside with the shorter ends of the pins sticking out the top. You can use a breadboard as a jig to keep them straight while soldering. Make sure you don’t fit them wonky or you might have trouble soldering the resulting assembly to the Clock board later. To save time, you don’t have to solder all 40 pins. We’ve marked all the pins that are actually used with triangles on the PCB silkscreen (also visible in Fig.3). You can refer to that and just solder the pins that are used. Those marked with “G” are ground pins, and theoretically you don’t need to solder all of those (but at least one or two). Still, you might as well do them all. Once you’ve finished that, add a little flux paste on each Pico W pad on the back of the PCB that you plan to solder, then rest the Pico W in place. Make sure it’s centred properly, then feed in some solder to a convenient pad from the side and melt it with the tip of your iron. Make sure it’s flowed onto both the PCB pad and pin, so that the module is no longer easy to move around. Check that the others are wellaligned, then solder one of the opposite pins. Proceed to solder the remainder. The module should be rigidly held in place once you’ve finished, despite only about a third of the pins being soldered. See the photo opposite for an idea of how it should look when finished. Testing The Clock isn’t finished yet, but it’s close enough to be able to test at this stage. Plug it into USB and you should see a green swirling pattern indicating that it has created a Wi-Fi access point but it can’t show the time yet. If you’ve already set up the Wi-Fi network, it should instead go to a red swirling pattern, then after about siliconchip.com.au 10-15 seconds, if it has successfully connected to your Wi-Fi network, it will change to mauve/purple. A few seconds later, the time display should come up. The LEDs should all work immediately. If you aren’t sure or want to check them, there are two buttons near the bottom of the web interface to test the LEDs. The first, “Test all LEDs”, lights them up white one at a time, starting with 12 o’clock and working its way clockwise around the clock face, then the AM/PM LEDs. It returns to the normal clock mode after that. The second, “Test colours”, lights up all LEDs red for 10s, then green for 10s, then blue for 10s, then returns to the normal clock mode. The time zone settings default to NSW/ACT/Vic/Tas, so if you’re elsewhere, the time may not be correct. You can access the setting page now, scroll down and change the time zone settings now, and the time should then be correct. Remember to save the changes when you’re happy. Remaining components Insert the LDR, pushing it in as far as you can while keeping it neat and centred. You’ll have to crank the leads a little; small pliers are helpful for that. Solder and trim the leads. If you don’t want to use the LDR, you can leave it off and simply disable automatic brightness control on the web page. If you’re going to feed in power via CON1, fit REG1 now, ensuring it is orientated as shown in Fig.3. Soldering it is a little tricky due to nearby components. We suggest adding flux paste to its pads before placing it, tack one pin, then once you’re happy with its alignment, add more flux paste on top. That will make bridges less likely. Clean the tip of your soldering iron, add a little solder and touch the tip to one pin, making sure to also touch the PCB pad so the solder flows onto both. Repeat until all pins are soldered. You’ll need to come in at a fairly steep angle to avoid D1 and the nearby capacitors. Inspect it with a magnifier. If you aren’t happy with any of the joints, or think the pins may be bridged, add more flux paste and use some solder wick coming in from above the chip to clean up the joints. Press your iron down onto the braid over the pins for a few seconds, then remove it. You should be rewarded with siliconchip.com.au v Parts List – Neopixel RGB LED ‘Analog’ Clock 1 Main PCB assembly (see below) 1 2-way right-angle header (CON1; optional) 1 GL5528 LDR (LDR1) 1 Pico W microcontroller module programmed with 1910125A.uf2 (MOD1) 2 20-pin low-profile header strips, 2.54mm pitch (for mounting MOD1) 1 AP5002 low-dropout buck regulator, SOIC-8 (REG1; optional) 1 200mm length of 0.7mm diameter tinned copper wire Main PCB assembly 1 double-sided PCB coded 19101252, 200 × 200mm (circular) with white solder mask 2 2A SMD ferrite beads, M3216/1206-size (FB1, FB2) 1 33μH 2.7A 12×12mm SMD inductor (L1) 2 6×3mm two-pin white SMD tactile pushbutton switches (S1, S2) Semiconductors 62 WS2812B addressable LEDs (LED1-LED62) 1 AO3400A 30V 5.8A N-channel Mosfet, SOT-23 (Q1) 1 BZX84C5V6 5.6V ±1% ¼W SMD zener diode, SOT-23 (ZD1) 1 BZG05C-5V6 40W peak zener diode, DO-214AC (ZD2) 1 SS34 40V 3A SMD schottky diode, DO-214AC (D1) Capacitors (all SMD M2012/0805-size MLCC unless noted) 1 220μF 25V SMD electrolytic, 8mm diameter 4 220μF 6.3V solid tantalum, SMB case 11 22μF 16V X5R M3216/1206 size 24 100nF 50V X7R 1 4.7nF 50V X7R 1 1nF 50V X7R Resistors (all SMD M2012/0805-size ±1% ⅛W) 2 100kW 1 10kW 1 6.8kW 1 1.3kW 1 1kW 4 330W Kit (SC7752, $85 + P&P): includes everything in the parts list, with the PCB already mostly assembled. GNSS modules are available separately: BZ-121 (miniature, 10Hz, $30) or VK2828U7G5LF (small, 1Hz, $25). When mounting the Pico W, we recommend using some headers so that it sits slightly above the PCB. If you want to mount it flush with the PCB, a USB connection might still be possible using a low-profile right-angle USB cable. Australia's electronics magazine November 2026  33 clean-­ looking solder joints on that side. Repeat if necessary. If feeding a regulated 5V supply to CON1, you can fit REG1 or use a short piece of wire to join the bottom two pads (4 & 5) to bypass it. You can fit a right-angle header for CON1 (plain or polarised/locking), or just solder wires there. You may want to avoid anything sticking through the front of the clock, or if it does project out the front, simply snip it flush with the face or the board while being careful not to damage the solder mask. Now apply 5-15V DC to CON1, paying attention to the polarity, and use a DMM to measure the voltage across ZD2. It should be close to +5V (say 4.75-5.25V) with the red probe on its cathode (striped end). If you get 0V or something else, or ZD2 is getting hot, REG1 may not be soldered properly, or your supply may be connected backwards. Switch off and check both. If you measure close to +5V, switch off and bridge LK1 with a solder blob, then reapply power and the clock should start up. Fitting a GNSS module If you want to use a GNSS/GPS module, you can connect and test it now. Find a good position for it on the back of the clock board, where the cable ends reach CON2 easily, and stick it in place with double-sided tape. Keep the antenna on the side away from the PCB. The copper planes on the PCB will reduce its sensitivity somewhat, but you can move it later if necessary. Depending on where you’re placing the clock, you may need a GNSS module with an external antenna connector Table 1 – common GNSS module connections CON2 BZ-121 VK2828 Neo-7M EN × Yellow × 0V Black Black GND RX White Green RXD TX Yellow Blue TXD +5 Red Red VCC PPS × White PPS to get a good signal (eg, a NEO-7M). Table 1 shows how to solder the wires for the three modules we sell. Others will be similar, but you’ll have to refer to the data sheet to figure it out. Only the 0V, 5V and TX connections are strictly necessary, although if your module has an enable pin and won’t run if it’s floating, you will need to connect that somewhere too. The EN pad is suitable as long as it’s active-high. Note that the TX and RX labels are from the point of view of the module and should match those functions on it (ie, the TX pin is what the Pico W uses to receive data and the RX pin is where it would transmit data). With the module wired up, power the Clock back up and switch the time source to GNSS in the user interface. If the module has an onboard LED (most do), you should see it light up. Once the Clock has connected to Wi-Fi, you should be able to access its page and see the GNSS status at upper-right. If it reads “no data”, that could mean the baud rate is wrong. The default is 115200, which suits the BZ-121. If your module needs a different baud rate (such as the VK2828, which defaults to 9600), enter it in the box. If you see the status change to “Receiving, no fix…” that means it’s correct now, so save the change. It can take upwards of 30 minutes for a module to get a lock on first poweron and that’s assuming there’s a good signal level, so you may have to wait a while before you see the status change to “Valid fix” or “Valid time”. Either should be fine for running the clock. If this isn’t working, there may be a wiring error. You can click the “GNSS Debug Window” button to open a window that should show the data coming from the module. If you aren’t seeing anything, or it’s garbage, and you’re sure the baud rate is correct, that could mean a wiring error. Unplug the Clock and check the wiring and that the module’s plug is inserted properly. Coming up next We decided to provide as much information in this article as possible to explain how the Clock works and allow you to get it up and running. However, we haven’t yet fully described how all the settings work, nor have we given any details on the firmware development and internal operation. The firmware is quite complex and could be useful as a starting point for another Wi-Fi based project using a Pico W or Pico 2 W. So if you’re interested in that, we’ll have more details in a follow-up article next month, along with the full usage instructions. In the meantime, if you’re curious about the firmware, the full source code is also available in the download SC package we linked to earlier. Configuring the clock via USB instead While the Wi-Fi & HTTP method (via a web browser) is the intended way to set up the clock, as it’s easier for most people, it’s also possible to set it up using a terminal program via its USB serial port. All the same settings are available that way. If you want to do this, plug it into your computer and check that a USB serial port is created. Connect to that using a program like PuTTY or Tera Term Pro (the baud rate isn’t important). Type “help” and press enter (a LF or \n character is expected after command). You should get a list of possible commands. Some relevant commands are: ● show settings – prints all the current settings to the terminal ● set x=y – change x to the setting you want to change (as per “show settings”) and y to the new value (true/false for boolean settings, a number for numeric; text otherwise) ● save settings – saves changes to flash ● wifi connect – connect to the network as configured via the SSID and password (will reconnect with the current settings if already connected) ● reboot If you’re not using a GNSS/GPS module (pictured above) as a time source, you can setup the clock via USB. Australia's electronics magazine siliconchip.com.au 34 Silicon Chip