Spying On The ESP32’s GPIO

January 1, 2024 by Bryan Cockfield 8 Comments

The ESP32 has been a go-to microcontroller platform for a while now, thanks to its versatile capabilities, integrated Wi-Fi and Bluetooth connectivity, and low power consumption. It’s ideal for a wide range of projects especially those revolving around IoT, partially because of all of the libraries and tools available for it now. The latest tool from [The Last Outpost Workshop] adds a feature we didn’t know we wanted until now: a webserver showing real-time updates of what all of the GPIO pins are doing.

The live GPIO pin monitoring library sets up the ESP32 to stream information about what all of the pins are doing in real time to a webserver, which displays the information as a helpful graphic. The demonstration in the video below shows and example troubleshooting a situation where the code is correct but there’s a mistake in the wiring, helping to quickly identify the problem and hopefully eliminating a wild goose chase for a bug in the software. The library can be quickly installed using the Arduino IDE and only requires the use of one other library and a few lines of code to get everything up and running.

As far as a debugging tool goes, something like this could save a lot of us a significant amount of time, especially with how easy it is to set up. A real-time look into the pins and their behavior, including those set up for PWM, is invaluable for plenty of situations. Of course if you’re building something like a real-time operating system that needs responses within a very specific interval you may want to look at more in-depth strategies for probing the GPIO.

Thanks to [Bob] for the tip!

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Odd Inputs And Peculiar Peripherals: RoenDi Smart Knob Thinks Outside The Box

June 27, 2022 by Dan Maloney 19 Comments

When it comes to design decisions, we’re often advised to “think outside the box.” It’s generally good advice, if a bit abstract — it could really mean anything. But it appears that someone took it quite literally with this nifty little smart knob display and input device.

[Dimitar]’s inspiration for RoenDi — for “rotary encoder and display” — came from an unusual source: a car dashboard, and specifically, the multipurpose knobs that often crop up in a car’s climate control cluster. Designed for ease of use while driving while causing as little distraction as possible, such knobs often combine a rotary encoder with one or more indicators or buttons. RoenDi builds on that theme by putting a 1.7″ round LCD display in the middle of a ring attached to an Alps rotary encoder, allowing the knob to be customized for whatever you want it to represent. The backplane sports a powerful STM32 microcontroller with a lot of the GPIO pins broken out, so customization and interfacing are limited only by your imagination. The design is open source, so you can either build your own or support the project via Crowd Supply.

Unlike the haptic smart knob we’ve been seeing a bit about lately, which also features a round LCD at its center, RoenDi’s feedback is via the physical detents on the encoder. We think both devices are great, and they fill different niches in the novel input ecosystem.

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Computer Vision Lets You Skip Songs With A Glance

November 2, 2021 by Tom Nardi 7 Comments

Have you ever wished you could control your home automation devices with nothing more than a withering stare? Well then you’re in luck, as [Norbert Zare] has come up with a clever way of controlling an MP3 player with only your face. Though as you might imagine, the technique could be applied to a whole range of home automation tasks with some minor tweaks.

At the core of this project is the Raspberry Pi, specifically the 3 B+ model, though with the computational demands of computer vision you might want to bump it up to the latest-and-greatest Pi 4. From there you need to load up OpenCV and a model trained for face detection, which as luck would have it, tends to be a fairly common application for this technology.

With a relatively simple Python script, [Norbert] is able to determine when OpenCV detects he’s looking directly into the camera and fire off one of the Pi’s GPIO pins that’s been connected to the “Skip” button on a physical MP3 player. That’s right, you read that correctly. He’s using a dedicated MP3 player in the year 2021.

In all seriousness, we’re not really sure why [Norbert] went this route compared to simply playing the music on the Pi and controlling it through software, but this does serve as a good example of how you can interface with physical devices if need be. In any event, using the Python script he’s provided, you could easily modify the setup to control other tasks, virtual or otherwise.

While face recognition can be a scary thing out in the wild, we do think it has some interesting applications within the home, so long as the user is the one who is in control of where their data ends up.

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Upgrade Board Adds GPIO Pins To Your Replica PDP-11

September 1, 2021 by Tom Nardi 10 Comments

Like many Hackaday readers, [Steven Stallion] has had his eyes on the replica PDP-11 created by [Oscar Vermeulen] for some time now, and this summer he finally got the opportunity to build one himself. But while most owners might be content to just watch the Raspberry Pi based faux-retro computer blink away on a shelf, he wanted to explore putting the machine to more practical use. The end result is the PiDP-11 I/O Expander, an add-on that lets the modern minicomputer interact with the world around it.

Developed after some discussion with [Oscar] himself, the Microchip MCP23016 based expander board fits neatly onto the PiDP-11 PCB, and [Steven] has made sure his installation guide meshes well with the replica’s documentation. The Pi’s I2C bus is actually broken out on the original PCB, so you just need to solder a header on and run some jumpers to where the expander is mounted. You’ll need to pull 5 V as well, and the installation guide has a few tips on convenient connection points.

Each expander board gives you 16 GPIO pins which can be accessed over I2C, including support for interrupts which has been connected to GPIO 19 on the Raspberry Pi. [Steven] notes that you should be able to stack multiples of his expander up should you need even more free pins, though some fiddling with pull-up resistors and I2C addresses will likely be necessary.

The PCBs for the expander have been released under the two clause BSD license, so you’re free to spin up your own copies however you see fit. But if you’d like to save some time, [Steven] is offering assembled boards on Tindie.

Since [Oscar] first teased it at the 2015 Hackaday Supercon, we’ve been enamored with his fantastic PDP-11 replica. We’re always glad to see when somebody has picked up one of these wonderful kits, and doubly so when they’ve figured out a way to expand it in unexpected ways.

Run Out Of GPIO On Your Pi? Don’t Despair!

April 28, 2021 by Jenny List 25 Comments

When the first Raspberry Pi rolled off the production line back in 2012 it sported a 26-pin expansion header that seemed to conceal endless possibilities. A later upgrade to the 40-pin header we have today unleashed a few more precious interfaces, but even then it’s still possible to run out. This was the problem faced by [woj], who needed a PWM line to drive a cooling fan but whose other work had used everything on the header. The solution? Dive into the other connectors on board looking for an unused GPIO.

Every full-sized Pi has a connector for the camera and the LCD screen, and to operate some of the functions of those peripherals they contain a few extra GPIOs that aren’t normally used by end users. If the camera or LCD is not being used then these lines are potentially up for grabs. In particular there’s a GPIO that turns the camera on or off that’s relatively easy to solder a wire to, and it was this one that fed the PWM line.

There are of course a few other ways to find some more lines on a Pi and indeed almost any microcontroller, with one of the many types of GPIO expansion chips. This trick is a particularly simple one though. and perhaps unsurprisingly it has surfaced here before.

Bridging The PC And Embedded Worlds With Pico And Python

April 18, 2021 by Stephen Ogier 17 Comments

Although protocols like I2C and SPI are great for communicating between embedded devices and their peripherals, it can be a pain to interface these low-level digital interfaces to a PC. [Alexandre] typically used an Arduino to bridge between the PC and embedded worlds, but he got tired of defining a custom serial protocol for each project. Inspired by MicroPython’s machine module, [Alexandre] has developed u2if—an implementation of some of MicroPython’s machine module for PC—using a USB-connected Raspberry Pi Pico to bridge between a PC and low-level digital interfaces.

u2if consists of two parts: the PC portion is a Python implementation of a portion of the MicroPython machine module, and the Raspberry Pi Pico receives some custom C++ firmware. Thus far, [Alexandre] has implemented functionality for the onboard ADCs, I2C, SPI, UART, and GPIO lines as well as additional support for I2S sound and the WS2812B addressable LED.

In addition to the u2if package, [Alexandre] has designed a PCB to break out all of the Raspberry Pi Pico’s interfaces in a handy 3×3.9″ board. We especially like that multiple headers are supplied for I2C, including one with enough space to mount an SSD1306 OLED display.

We think this could be an incredibly useful tool, and what makes it even more impressive is that it uses a board many of us already have laying around. If you want a dedicated device for interfacing with low-level digital buses, you may want to check out the GreatFET.

Waveshare’s Pi CM3 Laptop Arrives A Bit Too Late

December 3, 2020 by Tom Nardi 20 Comments

The good news it that you can now buy a pretty decent laptop that’s based around the Raspberry Pi Compute Module (CM). The bad news is that it was conceived before anyone knew the interface was going to change for the new CM4, so it doesn’t have any of the features that would make it really interesting such as support for PCI-Express. Oh, and it costs $300.

Waveshare, the company that most of us know best as a purveyor of e-paper displays, also made some rather interesting design choices on their laptop. See that black pad under the keyboard? No, it’s not a trackpad. It’s just a decorative cover that you remove to access an LED matrix and GPIO connectors. Make no mistake, a laptop that features a GPIO breakout right on the front is definitely our jam. But the decision to install it in place of the trackpad, and then cover it with something that looks exactly like a trackpad, is honestly just bizarre. It might not be pretty, but the Pi 400 seemed to have solved this problem well enough without any confusion.

On the other hand, there seems to be a lot to like about this product. For one, it’s a very sleek machine that doesn’t have the boxy and somewhat juvenile look that seems so common in other commercial Pi laptops. We also like that Waveshare included a proper Ethernet jack, something that’s becoming increasingly rare even on “real” laptops. As [ETA PRIME] points out in the video after the break, the machine also has a crisp IPS display and a surprisingly responsive keyboard. Though the fact that it still has a “Windows” key borders on being offensive considering how much it costs.

But really, the biggest issue with this laptop is when it finally hit the market. If Waveshare had rushed this out when the CM3 was first introduced, it probably would have been a more impressive technical achievement. On the other hand, had they waited a bit longer they would have been able to design it around the far more capable CM4. As it stands, the product is stuck awkwardly in the middle.

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