Serial And UPDI Handled Together With One Convenient Circuit

October 4, 2025 by Lewin Day 7 Comments

Sometimes it’s nice when you can do everything you need to do with just one single port. In this vein, [Nicola Strappazzon] whipped up a circuit to combine serial and UPDI programming in a very convenient way.

As an example, [Nicola] demonstrates the concept using an AVR128DA28 microcontroller. It’s paired with a 4052 multiplexer IC and a CH340 USB-to-serial chip. Everything is wired up such that the 4052 acts as a switch for the signal coming from the CH340. When the RTS flow-control signal is set high, it switches the 4052 to hook up the CH340’s RX and TX pins to the UDPI interface on the AVR microcontroller. Conversely, when the RTS signal is set low, the CH340 is instead hooked up to the serial UART on the microcontroller. From there, it’s a simple matter of configuring avrdude to properly set the RTS pin when attempting to program the attached device.

If you’re working with UPDI devices and you want to be able to talk to them and program them with a minimum of fuss, this project might be useful for you. We’ve looked at dedicated UPDI programmers before, too. If you’re cooking up your own nifty microcontroller hacks, don’t hesitate to let us know on the tipsline.

How Do The Normal People Survive?

October 4, 2025 by Elliot Williams 112 Comments

It was one of those weeks last week at Hackaday’s home office. My mother-in-law handed me her favorite power bank and said “it’s not charging”. She had every expectation that I’ll open it up, desolder the weary pouch inside, scrounge a LiPo out of some corner of the basement, and have it back up and running before the weekend. And of course that’s what happened, although maybe it looks a little worse for wear because it was hard to open the sealed case without excessive force. Sorry about that!

Then on the weekend, I finally got fed up with the decomposing foam on the face seal on my FPV goggles. It was leaking light all over the place. Of course I could have bought a new seal, but then I’d have to wait a week or so for delivery. So I pulled the velcro backing off, tossed it in the bed scanner, pulled the image up in Inkscape, converted it to Gcode, and cut out a couple seals out of EVA foam on the laser. Not only are they essentially indestructible, but I was able to customize them a little bit, and the fit is now better than ever.

And then, one of our neighbors bought a new garage door fob, flipped the DIP switches into the right configuration, and couldn’t figure out why it wouldn’t open the garage door. Knock knock knock. Using the tried-and-true RF probe that everyone with a scope probe has sitting around, namely hooking the ground pin to the tip and putting the radio device in the loop, it was clear that the sense of the DIP switches was inverted from what it said in the instructions. That was a fun little puzzle.

It was the garage door opener that triggered me to think about how normal people would handle any of these situations. “How do the normies even get by?” were the exact words that went through my head. And let’s face it: we’re not entirely normal. Normal people don’t have a soldering setup just sitting around ready to get hot 24/7, or a scope to diagnose a garage door RF transmitter at the drop of a hat. But these things seem to happen to me all the time. How do the normal people survive? Maybe they all know someone with a scope?

I take it as my service to the world to be “that guy” for most of our friends and family, and I pretty much do it without complaint. “With great power” and all that. My wife is just about as gracious when she’s stuck debugging a parent’s Windows setup, so I’m not saying I’m the only saint in the world, either. Surely you have similar stories.

But last week it made me reflect on how good we’ve got it, and that does make me want to pay it forward a little bit. If you’re one of the people who can, try to help out those who can’t.

A High Resolution ADC From Scratch

October 4, 2025 by Bryan Cockfield 6 Comments

It’s a well-known conundrum that while most computers these days are digital in nature, almost nothing in nature is. Most things we encounter in the real world, whether it’s temperature, time, sound, pressure, or any other measurable phenomenon comes to us in analog form. To convert these signals to something understandable by a digital converter we need an analog-to-digital converter or ADC, and [Igor] has built a unique one from scratch called a delta sigma converter.

What separates delta sigma converters apart is their high sampling rate combined with a clever way of averaging the measurements to get a very precise final value. In [Igor]’s version this average is provided by an op-amp that integrates the input signal and a feedback signal, allowing for an extremely precise digital value to be outputted at the end of the conversion process. [Igor] has built this one from scratch as well, and is using it to interface a magnetic rotary encoder to control digital audio playback.

Although he has this set up with specific hardware, he has enough detail in his video (including timing diagrams and explanations of all of the theory behind these circuits) for anyone else to build one of these for other means, and it should be easily adaptable for plenty of uses. There are plenty of different ADC topologies too, and we saw many different ones a few years ago during our op-amp challenge.

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How Your SID May Not Be As Tuneful As You’d Like

October 4, 2025 by Jenny List 6 Comments

The MOS Technologies 6581, or SID, is perhaps the integrated circuit whose sound is most sought-after in the chiptune world. Its three voices and mix of waveforms define so much of our collective memories of 1980s computing culture, so it’s no surprise that modern musicians seek out SID synthesisers of their own. One of these is the MIDISID, produced by [MIDI IN], and in a recent video she investigates an unexpected tuning problem.

It started when she received customer reports of SIDs that were out of tune, and in the video she delves deeply into the subject. The original SID gained its timing from a clock signal provided by the Commodore 64, with thus different timing between NTSC and PAL versions of the machine. This meant European SID music needed different software values to American compositions, and along the way she reveals a localisation error in that the British Commodore 64 manual had the wrong table of values.

Modern SIDs are emulated unless you happen to have an original, and her problem came when switching from one emulated SID to another. The first one used that clock pin while the second has its own clock, resulting in some music being off-tune. It’s a straightforward firmware fix for her, but an interesting dive into how these chips worked for the rest of us.

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Building A Ham Radio Data Transceiver On The Cheap

October 3, 2025 by Lewin Day 17 Comments

Once upon a time, ham radio was all about CW and voice transmissions and little else. These days, the hobby is altogether richer, with a wide range of fancy digital data modes to play with. [KM6LYW Radio] has been tinkering in this space, and whipped up a compact ham radio data rig that you can build for well under $100.

Radio-wise, the build starts with the Baofeng UV-5R handheld radio. It’s a compact VHF/UHF transceiver with 5W output and can be had for under $25 USD if you know where to look. It’s paired with a Raspberry Pi Zero 2W, which is the brains of the operation. The Pi is hooked up to the All-In-One-Cable which is basically a soundcard-like interface that plugs into USB and hooks up to the mic and speaker outputs of the Baofeng handheld. The final pieces of the puzzle are a USB PD battery pack and a small OLED screen to display status information.

What does that kit get you? The capability to transmit on all sorts of digital modes with the aid of the DigiPi software package. You can send emails, jump on APRS, or even chat on the web. You can configure all of this through a web interface running on the Raspberry Pi.

We’ve looked at some interesting digital ham projects before, too. Video after the break.

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When USB Charger Marketing Claims Are Technically True

October 3, 2025 by Maya Posch 20 Comments

The 600W is not the output rating, despite all appearances. (Credit: Denki Otaku, YouTube)

We have seen many scam USB chargers appear over the years, with a number of them being enthusiastically ripped apart and analyzed by fairly tame electrical engineers. Often these are obvious scams with clear fire risks, massively overstated claims and/or electrocution hazards. This is where the “600W” multi-port USB charger from AliExpress that [Denki Otaku] looked at is so fascinating, as despite only outputting 170 Watt before cutting out, it’s technically not lying in its marketing and generally well-engineered.

The trick being that the “600W” is effectively just the model name, even if you could mistake it for the summed up output power as listed on the ports. The claimed GaN components are also there, with all three claimed parts counted and present in the main power conversion stages, along with the expected efficiency gains.

While testing USB-PD voltages and current on the USB-C ports, the supported USB-PD EPR wattage and voltages significantly reduce when you start using ports, indicating that they’re clearly being shared, but this is all listed on the product page.

The main PCB of the unit generates the 28 VDC that’s also the maximum voltage that the USB-C ports can output, with lower voltages generated as needed. On the PCB with the USB ports we find the step-down converters for this, as well as the USB-PD and other USB charging control chips. With only a limited number of these to go around, the controller will change the current per port dynamically as the load increases, as you would expect.

Considering that this particular charger can be bought for around $30, is up-front about the limitations and uses GaN, while a genuine 300 Watt charger from a brand like Anker goes for $140+, it leads one to question the expectations of the buyer more than anything. While not an outright scam like those outrageous $20 ‘2 TB’ SSDs, it does seem to prey on people who have little technical understanding of what crazy amounts of cash you’d have to spend for a genuine 600 Watt GaN multi-port USB charger, never mind how big such a unit would be.

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Cold Sensor, Hot Results: Upgrading A DSLR For Astrophotography

October 3, 2025 by Matt Varian 14 Comments

When taking pictures of the night sky, any noise picked up by the sensor can obscure the desired result. One major cause of noise in CMOS sensors is heat—even small amounts can degrade the final image. To combat this, [Francisco C] of Deep SkyLab retrofitted an old Canon T1i DSLR with an external cooler to reduce thermal noise, which introduces random pixel variations that can hide faint stars.

While dedicated astrophotography cameras exist—and [Francisco C] even owns one—he wanted to see if he could improve an old DSLR by actively cooling its image sensor. He began with minor surgery, removing the rear panel and screen to expose the back of the sensor. Using a sub-$20 Peltier cooler (also called a TEC, or Thermoelectric Cooler), he placed its cold side against the sensor, creating a path to draw heat away.

Reassembling the camera required some compromises, such as leaving off the LCD screen due to space constraints. To prevent light leaks, [Francisco C] covered the exposed PCBs and viewfinder with tape. He then tested the setup, taking photos with the TEC disabled and enabled. Without cooling, the sensor started at 67°F but quickly rose to 88°F in sequential shots. With the TEC enabled, the sensor remained steady at 67°F across all shots, yielding a 2.8x improvement in the signal-to-noise ratio. Thanks to [Francisco C] for sharing this project! Check out his project page for more details, and explore our other astrophotography hacks for inspiration.

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