As of next week, KiCad 9 should be about to release. One of the many exciting features, to me, is that it now includes a footprint generator that I contributed, for capacitive scrollwheels. It’s based on the Atmel (now Microchip) appnote AN294 Self-Capacitance Sensors. Interestingly, the image displayed in the appnote does not actually… Read More: Capacitive Scrollwheels in KiCad »
Simulation has always been the dream of PCB design. In most cases, it hasn’t been practical – Either in the domain of expensive or esoteric tools that are compute-cycle hungry and limited in scope. But we’re at a turning point. This is the process for current carrying / voltage potential simulations with KiCad and ElmerFEM.… Read More: Open-Source Thermal Simulation of PCBs »
From Wikipedia: Force-directed graph drawing algorithms are a class of algorithms for drawing graphs in an aesthetically-pleasing way. Their purpose is to position the nodes of a graph in two-dimensional or three-dimensional space so that all the edges are of more or less equal length and there are as few crossing edges as possible, by… Read More: Force-Directed Circuit Board Footprint Autoplacement »
Voltage glitching, also called fault injection, is the process of dumping the energy on a microcontroller’s power rail very briefly – Just enough to cause a glitch, where it skips an instruction, rather than causing a brown-out-induced reset. I first learned about the technique in connection with the Chip Whisperer, which is an FPGA-based board… Read More: Dumping Firmware With a 555 »
Here is a brief overview of how light and colour work, in the context of LED lighting. We’ll mostly be discussing the CIE 1931 colour space, with reference to the chromaticity diagram, shown below. This is the 1931 version. Newer versions that look slightly different have come out, but the general intent is the same,… Read More: Chromaticity »
I’ve alluded to this in the past, once or twice. Power management in battery applications is pretty tricky. There are a lot of different situations, and a lot of different strategies. In the past, for the topic of this conversation, single cell Lithium polymer batteries, I’ve used a pair of Schottky diodes to automatically “select”… Read More: LiPo Systems with USB Power »
Here’s an issue that was causing me some grief: In newer versions of MPLAB X, Microchip’s IDE, My PicKit 3 clone wasn’t able to supply power anymore. Some investigation revealed that in MPLAB 8 and before, they didn’t used to properly check for “correct” voltage before attempting to continue programming. Which is great! But they… Read More: PicFix »
A lot of the switch-mode power supplies I’ve built have relied on Skyworks Technologies controllers. This is because they are very cheap, and seem to go obsolete almost immediately after purchase. This is a quick story of bringing up a new switch-mode circuit from a different manufacturer to test its viability in some battery-powered devices.… Read More: Storytime! A switch mode tale. »
TLDR: I wrote an Inkscape extension to make my life a little bit easier when designing assemblies with laser cutters. For the most part, I avoid using 3D printers while rapidly prototyping. Until very recently, they have been little better than toys; unreliable, inaccurate, and high maintenance. The laser cutter, however, is a… Read More: Rapidly Building Software to Prototype Quickly »
Jumping off from my last post about getting images into Altium Designer, it was surprisingly difficult to do in CircuitMaker. After three days of attempting a few different approaches, I have one that I’m quite happy with. Conveniently, this is pretty good at getting images into EAGLE as well. At least as good as the built-in ULP. If… Read More: Getting Images into CircuitMaker »