As with most of my projects lately, I’m finding that I’m playing catch up with the documentation, so this is an old one. This project is a bit of a twofer, because it was the demo project for Stretch, my Kicad plugin. Did I say I have a backlog? Stretch was a pandemic project, initially… Read More: Jet »
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 »
Instead of a TV at home, I use a projector. It’s on my ceiling, with the buttons inaccessible. The remote for it also isn’t really working anymore. Problem. There’s nothing on the remote control’s PCB except for an obscure microcontroller (TTR013), IR LED and driving transistors, and some carbon contacts for the buttons. The intermittent… Read More: Very Remote Control »
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 »
I bought a used lathe. It’s a Craftex B1979C, which seems to be nearly identical to a Craftex CX704. Similar to many such mini lathes, actually, with varying swing lengths. The previous owner explained, a little bit sheepishly, that he tried to cut steel a little too hard, and burned out the AC motor.… Read More: Strange New Bedroom Furniture »
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 »