Print-in-Place Connectors Aim To Make Wiring Easier

One thing some of us here in the United States have always been jealous of is the WAGO connectors that seem so common in electrical wiring everywhere else in the world. We often wonder why the electrical trades here haven’t adopted them more widely — after all, they’re faster to use than traditional wire nuts, and time is money on the job site.

Wago 221 compact lever connector via the Wago YouTube channel

This print-in-place electrical connector is inspired by the WAGO connectors, specifically their Lever Nut series. We’ll be clear right up front that [Tomáš “Harvie” Mudruňka’s] connector is more of an homage to the commercially available units, and should not be used for critical applications. Plus, as a 3D-printed part, it would be hard to compete with something optimized to be manufactured in the millions. But the idea is pretty slick. The print-in-place part has a vaguely heart-shaped cage with a lever arm trapped inside it.

After printing and freeing the lever arm, a small piece of 1.3-mm (16 AWG) solid copper wire is inserted into a groove. The wire acts as a busbar against which the lever arm squeezes conductors. The lever cams into a groove on the opposite wall of the cage, making a strong physical and electrical connection. The video below shows the connectors being built and tested.

We love the combination of print-in-place, compliant mechanisms, and composite construction on display here. It reminds us a bit of these printable SMD tape tamers, or this print-in-place engine benchmark.

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Ghidra Used To Patch Fahrenheit Into An Air Quality Meter

Even though most of the world population couldn’t tell you what room or body temperature is in Fahrenheit, there are some places on this globe where this unit is still in common use. For people in those areas, it’s therefore a real hassle when, say, a cheap Chinese air quality measurement systems only reports in degrees Celsius. Fortunately, [BSilverEagle] managed to patch such a unit to make it display temperature in Fahrenheit.

The reverse engineering begins by finding a way to dump the firmware. It’s nice to hear that [BSilverEagle] used some the skills demonstrated in [Eric Shlaepfer’s] PCB reverse engineering workshop from Hackaday Remoticon last November to trace out the debug header and the SWD pins of STM32F103C8 MCU. After that, OpenOCD could be used to dump the firmware image, with no read protection encountered. The firmware was then reverse-engineered using Ghidra, so that [BSilverEagle] could figure out where the temperature was being calculated and where the glyph for the Celsius symbol was stored. From there this it was a straight-forward rewrite of those two parts of the original firmware to calculate the temperature value in Fahrenheit, change the glyph and reflash the MCU.

So why buy this thing in the first place if it didn’t spit out units useful for your current locale? Cost. Buying this consumer(ish) device was about the same cost as buying the individual parts, designing and manufacturing the PCB, and writing the firmware for it. The only downside for their use case was the lack of Fahrenheit. Not a problem for those who demand full control of the hardware they own.

Need a boot camp for using Ghidra? Matthew Alt put together a spectacular video series on Reverse Engineering with Ghidra.