Microcontrollers

2288 Articles

Simple Stopwatch with two buttons, an eight digit 7-segment display and ICSP programming cable going into the board

Add An OSHW Certified Stopwatch To Your Toolkit

September 23, 2022 by 5 Comments

[MakingDevices] has created a simple stopwatch that makes for a nice introduction to surface mount electronic design and assembly. The project is open source hardware (OSHW) certified, with Gerbers, KiCAD files, and software all available.

Conceptually the stopwatch is straight forward, with a row of two four digit seven-segment displays being driven by a PIC18LF14k50 microcontroller through multiple NPN transistors. The PIC doesn’t quite have enough data lines to drive the two displays at once so an inverter is used to toggle between the two seven-segment blocks.

The circuit is continuously powered from a CR2032 coin cell battery. For normal usage with display, [MakingDevices] estimates 30+ hours of operation and 140+ hours without display, but still counting time. When idle, the “Extreme Low-Power (XLP)” capabilities of the PIC put the operating window estimates well beyond the self discharge of the coin cell battery. There’s an in circuit serial programming (ICSP) footprint that accepts a pogo pin TC2030-MCP-NL adapter for flashing the PIC.

Don’t let the simplicity fool you, this is a well documented project with detailed posts about the design, simulation and battery consumption. Various videos and glamour shots give a whole picture of the process, from design, assembly, testing to final validation.

It’d be wonderful to see the project extended or hacked on further, perhaps with a cute enclosure or case.

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For The ESP’s Next ESP Trick…

September 23, 2022 by 10 Comments

It is a pretty stale dad joke to tell someone you have ESP when you mean you have an ESP8266 or ESP32 in your hand. However, [Naufil Metkar] uses an ESP device to pretend — via a magic trick — that he does have ESP. The trick requires a bit of 3D printing, an MPU6050 gyro sensor, and a lot of showmanship.

We hate to spoil an illusion, but you can probably figure it out from the list of things you need. The die has a gyro in it and uses a small ESP module to transmit its current orientation out to a display. There is a small reed switch that lets you turn off the device with a magnet. Without it, the battery dies quickly.

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Hackaday Prize 2022: Solar Powered LoRa Weather Station For The Masses

September 22, 2022 by 20 Comments

[Debasish Dutta] has designed a few weather stations in the past, and this, the fourth version of the system has had many of the feature requests from past users rolled in. The station is intended to be used with an external weather sensor unit, provided by Sparkfun. This handles wind speed and direction, as well as measuring rainfall. A custom PCB hosts an ESP32-WROOM module and an Ai-Thinker Ra-02 LoRa module for control and connectivity respectively. A PMS5003 sits on the PCB to measure those particulate densities, but most sensors are connected with simple 4-way I2C connectors. Temperature, humidity, and pressure are handled by a BME280 module, UV Index (SI1145), visible light (BH1750) even soil humidity and temperature with a cable-mounted SHT10 module.

All this is powered by a solar panel, which charges a 18650 cell, and keeps the show running during the darker hours. For debugging and deployment, a USB-C power port can also be used to provide charge. A 3D printed Stevenson screen type enclosure allows the air to circulate amongst the PCB-mounted sensor modules, without hopefully too much moisture making it in there to cause mischief.

On the data collection and visualization side, a companion LoRa receiver module is in progress, which is intended to pass along measurements to a variety of services. Think Home Assistant, ESP home, and that kind of thing. Software is still a work in progress, so maybe check back later to see how [Debasish] is getting on with that?

This kind of multi-sensor hosting project is nothing new here, here’s a 2019 Hackaday prize entry along the same lines. Of course, gathering and logging measurement data is only part of the problem, visualization of those measurements is also important. Why not use a mechanical approach, such as a diorama?

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The Inner Machinations Of The Arduino Are An Enigma

September 19, 2022 by 88 Comments

Arduinos have been the microcontroller platform of choice for nearly two decades now, essentially abstracting away a lot of the setup and lower-level functions of small microcontrollers in favor of sensible IDEs and ease-of-use. This has opened up affordable microcontrollers to people who might not be willing to spend hours or days buried in datasheets, but it has also obscured some of those useful lower-level functions. But if you want to dig into them, they’re still working underneath everything as [Jim] shows us in this last of a series of posts about interrupts.

For this how-to, [Jim] is decoding linear timecodes (LTCs) at various speeds. This data is usually transmitted as audio, so the response from the microcontroller needs to be quick. To make sure the data is decoded properly, the first thing to set up is edge detection on the incoming signal. Since this is about using interrupts specifically, a single pin on the Arduino is dedicated to triggering an interrupt on these edges. The rest of the project involves setting up an interrupt service routine, detecting the clock signal, and then doing all of the processing necessary to display the received LTC on a small screen.

The project page goes into great detail about all of this, including all of the math that needs to be done to get it set up correctly. As far as general use of interrupts goes, it’s an excellent primer for using the lower-level functionality of these microcontrollers. And, if you’d like to see the other two projects preceding this one they can be found on the first feature about precision and accuracy, and the second feature about bitbanging the protocol itself.

ESP32 Adds Bluetooth To An IPod Nano

September 14, 2022 by 4 Comments

The iPod Nano was one of Apple’s masterworks, but it’s really tied down by its dependence on wired headphones. At least, that’s what [Tucker Osman] must have thought, as he spent an unreasonable amount of time designing a Bluetooth mod for the 3rd gen Nano. And it’s a thing of beauty — temperamental, brutally difficult to build, and fragile in use, but still beautiful. And while some purists try to keep their signal analog, [Tucker]’s coup d’etat is to intercept the iPod’s audio signal before the DAC chip, keeping the entire signal path digital to the Bluetooth speaker. Oh, and he also managed to make the volume and track skip buttons work, back across the wireless void.

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This Pico-W IoT Starter Project Gets You Into Home Assistant Quick As A Flash

September 3, 2022 by 20 Comments

Many of us hacker types with some hardware knowledge and a smattering of embedded experience would like to get into home automation, but there can be quite a learning curve. If you’re looking for a hackable starting point; something to deploy, learn about and then later expand upon, then look no further than the PicoW Home Assistant Starter project from [Danilo Campos].

The project is based upon the arduino-pico core, which supports a whole pile of RP2040-based boards, so you don’t need to restrict yourself to the “official” Pico-W, so long as you have working networking, Wi-Fi or otherwise. Integration is provided by the arduino-home-assistant library, which acts as the bridge between your sensors and other widgets, MQTT, and thence the network beyond. Events and sensor data on the end-point are packaged up with MQTT and published out to the broker via the network provided, all for minimal initial effort. Once you’ve got the basic connectivity to your Home Assistant instance working, there are many code examples in the arduino-home-assistant GitHub page to give you a helping start to connect whatever tickles your fancy.

It turns out we’ve covered HA quite a bit on these fair pages, like for example, these sweet automated window blinds. Another hack uses load cells under the bed legs to detect if someone is in bed or not, and if this isn’t your thing, maybe your idea of a home assistant is a bit more like this one?

Custom Calculator Brings Us Back To The 70s

September 1, 2022 by 7 Comments

There are certain design aesthetics from every era that manage to survive the fads of their time and live throughout history. Ancient Greek architecture is still drawn upon for design inspiration in modern buildings, the mid-century modern style from the 60s still inspires various designs of consumer goods, and the rounded, clean looking cars from the 90s are still highly desirable qualities in automotive design. For electronics, though, we like this 70s-inspired calculator that [Aaron] recently built.

The calculator hearkens back to the days of calculators like the HP-29C with its large buttons and dot-matrix display. [Aaron] built the case out of various woods with a screen angled towards the user, and it uses a LCD display similar to those found in antique calculators. The brain of the calculator is an Arduino which fits easily into the case, and [Aaron] also built the keyboard from scratch with Cherry MX-style mechanical keys soldered together into a custom shape.

The software to run the calculator is fairly straightforward, but we are most impressed with the woodworking, styling, and keyboard design in this build. [Aaron] is also still ironing out some bugs with the power supply as it uses a DC-DC converter to power the device from a single lithium battery. For those who are more fond of early 2000s graphing calculators instead, be sure to take a look at this graphing calculator arcade cabinet.

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