Two of these boards next to each other, one showing the front, assembled, side with the MCU and supporting components soldered on, and the other showing the back, patch panel, side, with wires connecting the MCU pads to testpoints leading to the supporting components

Try Out MCUs With This Jumperable TSSOP20 Adapter

June 29, 2024 by Arya Voronova 7 Comments

There are so many new cool MCUs coming out, and you want to play with all of them, but, initially, they tend to be accessible as bare chips. Devboards might be hard to get, not expose everything, or carry a premium price. [Willmore] has faced this problem with an assortment of new WCH-made MCUs, and brings us all a solution – a universal board for TSSOP20-packaged MCUs, breadboard-friendly and adaptable to any pinout with only a few jumpers on the underside.

The board brings you everything you might want from a typical MCU breakout – an onboard 3.3V regulator, USB series resistors, a 1.5K pullup, decoupling capacitors, and a USB-C port. All GPIOs are broken out, and there’s a separate header you can wire up for all your SWD/UART/USB/whatever needs – just use the “patch panel” on the bottom of the board and pick the test points you want to join. [Willmore] has used these boards for the CH32Vxxx family, and they could, no doubt, be used for more – solder your MCU on, go through the pin table in the datasheet, do a little point-to-point wiring, and you get a pretty functional development board.

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$3 Smartwatch Can Run Python

June 26, 2024 by Al Williams 9 Comments

[Poking Technology] doesn’t think much of his new smartwatch. It is, by his admission, the cheapest possible smartwatch, coming in at about $3. It has very few useful features but he has figured out how to port MicroPython to it, so for a wrist-mounted development board with BLE, it might be useful. You can check it out in the video below.

The first step is a teardown, which reveals surprisingly little on the inside. There’s a tiny battery, a few connections, a display, and a tiny CPU board. There are, luckily, a few test pads that let you get into the CPU. What do you get? A 24 MHz Telink CPU with 512k of flash and 16k of RAM, along with all the other hardware.

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screenshot of the code defining a hid descriptor by using essentially macros for common descriptor types

Coupling STM32 And Linux? Consider HID Over I2C

June 26, 2024 by Arya Voronova 25 Comments

If you’re pairing a tiny Linux computer to a few peripherals — perhaps you’re building a reasonably custom Pi-powered device — it’s rightfully tempting to use something like an STM32 for all your low-level tasks, from power management to reading keyboard events.

Now, in case you were wondering how to tie the two together, consider HID over I2C, it’s a standardized protocol with wide software and peripheral support, easily implementable and low-power. What’s more, [benedekkupper] gives you an example STM32 project with a detailed explanation on how you too can benefit from the protocol.

There are several cool things about this project. For a start, its code is generic enough that it will port across the entire STM32 lineup nicely. Just change the pin definitions as needed, compile it, flash it onto your devboard and experiment away. Need to change the descriptors? The hid-rdf library used lets you define a custom descriptor super easily, none of that building a descriptor from scratch stuff, and it even does compile-time verification of the descriptor!

The project has been tested with a Raspberry Pi 400, and [benedekkupper] links a tutorial on quickly adding your I2C-HID device on an Linux platform; all you need is DeviceTree support. Wondering what’s possible with HID? We’ve seen hackers play with HID aplenty here, and hacking on the HID standard isn’t just for building keyboards. It can let you automate your smartphone, reuse a laptop touchpad or even a sizeable Wacom input surface, liberate extra buttons on gamepads, or build your own touchscreen display.

ESP32 Brings New Features To Classic Geiger Circuit

June 24, 2024 by Tom Nardi 4 Comments

There’s no shortage of Geiger counter projects based on the old Soviet SBM-20 tube, it’s a classic circuit that’s easy enough even for a beginner to implement — so long as they don’t get bitten by the 400 volts going into the tube, that is. Toss in a microcontroller, and not only does that circuit get even easier to put together and tweak, but now the features and capabilities of the device are only limited by how much code you want to write.

Luckily for us, [Omar Khorshid] isn’t afraid of wrangling some 0s and 1s, and the result is the OpenRad project. In terms of hardware, it’s the standard SBM-20 circuit augmented with a LILYGO ESP32 development board that includes a TFT display. But where this one really shines is the firmware.

With the addition of a few hardware buttons, [Omar] was able to put together a very capable interface that runs locally on the device itself. In addition, the ESP32 serves up a web page that provides some impressive real-time data visualizations. It will even publish its data via MQTT if you want to plug it into your home automation system or other platform.

Between the project’s Hackaday.io page and GitHub repository, [Omar] has done a fantastic job of documenting the project so that others can recreate it. That includes providing the schematics, KiCad files, and Gerbers necessary to not only get the boards produced and assembled, but modified should you want to adapt the base OpenRad design.

This project reminds us of the uRADMonitor, which [Radu Motisan] first introduced in 2014 to bring radiation measuring to the masses. This sort of hardware has become far more accessible over the last decade, bringing the dream of a globally distributed citizen-operated network of radiation and environmental monitors much closer to reality.

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Fixed Point Math Exposed

June 23, 2024 by Al Williams 50 Comments

If you are used to writing software for modern machines, you probably don’t think much about computing something like one divided by three. Modern computers handle floating point quite well. However, in constrained systems, there is a trap you should be aware of. While modern compilers are happy to let you use and abuse floating point numbers, the hardware is often woefully slow. It also tends to eat up lots of resources. So what do you do? Well, as [Low Byte Productions] explains, you can opt for fixed-point math.

In theory, the idea is simple. Just put an arbitrary decimal point in your integers. So, for example, if we have two numbers, say 123 and 456, we could remember that we really mean 1.23 and 4.56. Adding, then, becomes trivial since 123+456=579, which is, of course, 5.79.

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A solar-powered decibel meter the size of a business card.

2024 Business Card Challenge: NoiseCard Judges The Sound Around You

June 22, 2024 by Kristina Panos 6 Comments

Let’s face it: even with the rise of the electric car, the world is a noisy place. And it seems like it has only gotten worse in recent years. But how can we easily quantify the noise around us and know whether it is considered an unhealthy decibel level?

That is where the NoiseCard comes in. This solar-powered solution can go anywhere from the regrettable open office plan to the busy street, thanks to a couple of 330 µF capacitors. It’s based on the low-power STM32G031J6 and uses a MEMS microphone to pick up sound from the back of the card, which the code is optimized for. Meanwhile, the LEDs on the front indicate the ambient noise level, ranging from a quiet 40 dB and under to an ear-splitting 105 dB or greater.

When it comes to building something the size of a business card, every component is under scrutiny for size and usefulness. So even the LEDs are optimized for brightness and low power consumption. Be sure to check it out in action after the break in various environments.

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ESP32 Powers Single-PCB ZX Spectrum Emulator

June 16, 2024 by Tom Nardi 21 Comments

When word first got out that the Chinese board houses were experimenting with full color silkscreens, many in our community thought it would be a boon for PCB art. Others believed it would be akin to cheating by removing the inherent limitations of the medium. That’s not a debate that will be solved today, but here we have an example of a project that’s not only making practical application of the technology, but one that arguably couldn’t exist in its current form without it: a single-PCB ZX Spectrum emulator developed by [atomic14].

There basics here are, well, they’re pretty basic. You’ve got an ESP32-S3, a TFT display, a micro SD slot, and the handful of passives necessary to tie them all together. What makes this project stand out is the keyboard, which has been integrated directly into the PCB thanks to the fourteen pins on the ESP32-S3 that can be used as touch sensor input channels. There are issues with detecting simultaneous keypresses, but overall it seems to work pretty well.

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