It’s Linux – But On An ESP32

July 21, 2021 by 44 Comments

GNU/Linux is an open-source marvel that has over the past three decades given us an almost infinitely versatile and powerful UNIX-like operating system. But even it has its limitations, particularly at the lower end of the hardware scale where less fully-featured processors often lack the prerequisites such as a memory management unit. Thus [JuiceRV]’s feat of booting a Linux kernel on an ESP32 microcontroller seems impossible, what’s happening?

The ESP’s dual 32-bit Xtensa cores are no slouch in the processing power department, but without that MMU it’s not an obvious Linux candidate platform. The solution to this problem comes in the form of an emulated RISC-V virtual machine which provides just enough grunt for a Linux 5.0.0 kernel to boot.

By any measure this represents an impressive piece of work, but will this new-found ability to run Linux on a microcontroller take the world by storm? Of course not, unless your tastes run to the very slowest of computing experiences. It is however the essence of the hack, and for that we salute it.

It’s not the first time Linux has run on a microcontroller, in the past someone hooked up a 30 pin SIMM and an SD card to an 8-bit Atmel chip and did it in a similar way with an ARM emulator.

Via CNX Software.

Header image: Ubahnverleih, CC0.

Giving Control Of A Smartphone Robot To A Raspberry Pi

July 21, 2021 by 3 Comments

Most gadgets that interface with smartphones have a rather short lifespan and inevitably end up as E-waste. Unless hackers give them a second life, as is the case with the Romo, a little smartphone-controlled robot. [David Goeken] has successfully reverse-engineered the communication protocol to allow the Romo to controlled Raspberry Pi (or microcontroller)

The Romo was a little iPhone-controlled robot brought to market with a Kickstarter campaign back in 2013. It originally used the audio jack from the iPhone for the control interface, but was quickly followed by an updated version that used iPhone 4’s 30 pin connector and later the Lightning port. Romotive, the company behind Romo, eventually went out of business, but fortunately, they open-sourced the IOS app and the firmware. This has led to a few third-party apps currently on the app store.

[David] wanted to use other hardware for control, so he set about reverse-engineering the protocol using the open-source software and a logic analyzer. Unsurprisingly, it uses a serial interface to send and receive commands, with two additional pins to detect the connection and wake up the Romo. After breaking out the interface header on the board, he was able to modify the Romo to mount a Raspberry Pi Zero, and power it using the internal battery.

[David] has not made his code public yet, but it sounds like he plans to. It looks like Romo’s can be a fun little experimentation platform, and they can be found for cheap on eBay. We covered another cool Romo hack back in 2014, which used a projector and vision system to create a Mariokart-like game.  For a completely open-source smartphone robot, check out the OpenBot.

Injection Molds From Your 3D Printer

July 20, 2021 by 5 Comments

Last time we checked in with [CrafsMan] he had bought a benchtop injection molding machine. This time, he shows off how to 3D print molds. If you have ever had to spend to make tooling for injection molding, you’ll appreciate being able to make molds relatively inexpensively.

To test his workflow, [CrafsMan] created a little 3D figurine and brought it into TinkerCad. From there he created a mold and used Lychee Slicer to print it using resin.

Continue reading “Injection Molds From Your 3D Printer” →

AppCAD Does Transmission Lines

July 20, 2021 by 7 Comments

Broadcom and Agilent are perhaps not household words in every household, but among those who work with RF, they are common enough names. An Agilent developer wrote AppCAD to help with common RF design computations and now works for Avago who bought Broadcom. But whoever’s branding is on it, you can download the tool from Broadcom or check out the latest beta version. Then watch [IMASI Guy’s] video below on how to use part of it.

What can it do? According to the website:

  • S-Parameter Analysis and Plotting
  • Active Circuit Bias Design
  • Cascade Noise and IP3 Analysis
  • Transmission Line Analysis
  • Signals and Systems
  • Complex Math Engineering Calculator

Continue reading “AppCAD Does Transmission Lines” →

Live Energy Monitor Helps Plan Power-Hungry Appliance Use

July 20, 2021 by 8 Comments

There are a lot of good reasons to have a better understanding of one’s household power use, and that is especially true for those that do their own solar power collection. For example, [Frederick] determined that it would be more efficient to use large appliances (like a dishwasher or washing machine) when there was excess solar power available, but the challenge was in accessing the right data in a convenient way. His Raspberry Pi-based live energy monitor was the solution, because it uses an LED matrix to display live energy data that can be consulted at a glance.

Interestingly, this project isn’t about hacking the power meter. What this project is really about is conveniently accessing that data when and where it is best needed. [Frederick] has a digital power and gas meter with the ability to accept a small wireless dongle. That dongle allows a mobile phone app to monitor power usage, including whether power is being taken from or exported to the grid.

Since [Frederick] didn’t want to have to constantly consult his mobile phone, a Raspberry Pi using a Pimoroni Unicorn HAT HD acts as a glanceable display. His Python script polls the power meter directly over WiFi, then creates a live display of power usage: one LED for every 250 W of power, with the top half of the display being power used, and the bottom half representing power exported to the grid. Now the decision of when to turn on which appliances for maximum efficiency is much easier, not by automating the appliances themselves, but simply by displaying data where it needs to be seen. (This kind of thing, incidentally, is exactly the idea behind the Rethink Displays challenge of the 2021 Hackaday Prize.)

As for those of us without a digital power meter that makes it easy for residents to access power data? It turns out there is no reason a power meter’s wireless service interface can’t be sniffed with RTL-SDR.

DIY Fume Extractor Keeps Air Clean While You Solder

July 20, 2021 by 17 Comments

Soldering is a key skill to learn when building electronics, but it’s also a process that can put out a lot of fumes. The best way to deal with this is to use a fume extractor. Of course, you can always make your own, as [Open Green Energy] ably demonstrates. It’s a guided build of the design [rdmmkr] published on Thingiverse.

The build relies on a 120mm case fan for suction, and it’s combined with a activated carbon filter to best capture the harmful fumes from the soldering process. The fan is neatly installed inside a 3D printed enclosure of custom design, which also includes a removable tray which holds the filter material. The fan is run from a DC power supply via a barrel jack, and a basic speed controller is installed to allow the fan to be turned up higher for more suction, or lower to reduce noise.

It’s a useful item to have around the home workshop, and it’s something that you could easily whip up at home with parts from the junk bin if you’re so inclined. The benefit of 3D printing is that you can easily alter the design to suit whatever parts you have on hand.

We’ve seen a few fume extractor builds over the years, from the simple and basic to the very fancy. Video after the break.

Continue reading “DIY Fume Extractor Keeps Air Clean While You Solder” →

One Giant Button To Mute Them All

July 20, 2021 by 3 Comments

The second round of this year’s Hackaday Prize is coming to a close, and we asked you to come up with ways of refreshing work-from-home life. Well here’s one we probably all could use — a large emergency mute button that can also turn off video with an extra click. You know, in case your kid or your roommate decides to walk around in their birthday suit.

[Colin Russell-Conway]’s software-agnostic mute button uses a Seeeduino Xiao and rotary encoder, plus three momentaries that give it a second function as a media controller. Two chunks of LED strip go blinky blinky when the mute is on, and are otherwise solidly lit and color-coded by videoconference type — blue for Zoom and Starleaf, green for Webex, and purple for Teams.

The companion app that [Colin] created is using the Windows Management Instrumentation (WMI) to check which program is control of the microphone. Whenever the mute button is pressed, the app makes note of the current program in focus, switches to the active videoconference, mutes it, and then switches back to reddit or twitch or whatever you had in focus when the kid started screaming for you from the bathroom. Check out the demo after the break.

Some of us like to celebrate a little when videoconferences are over. For those people, there is the pull-chain exit.

Continue reading “One Giant Button To Mute Them All” →