In preparation for Halloween this year, I built a large and colorful LED matrix. After programming it with monster-themed animations, it looked fantastic! Months passed, and when October 31st finally arrived, at dusk I hung the LED display outside by…
How quickly can a microcontroller detect and respond to changing inputs? Fast enough to replace a dedicated combinatorial logic chip, like a mux? I finally have some test results to begin answering this question. My goal here is a potential…
A prototype for the latest Star Ring. Q1, Q2, and Q3 use this N-channel MOSFET. The circuit runs from a 3V battery. When one of the transistors is turned on, the six red/green LEDs in the associated row can be…
The Atmel ICE programmer/debugger has its SWD connector pins reversed from the standard ARM Cortex debug connector. Arghh… why? It’s the same physical connector (5×2 0.05 inch polarized male), but the pins are rotated 180 degrees from the standard, as…
How efficient is a typical 5V AC-to-DC power supply? I’m digging through my box of assorted power supplies from past projects, looking for something appropriate for a large LED matrix, and noticed the one pictured above. 110V 0.8A input –…
I’m experimenting with methods to limit the inrush current when an SD card is inserted, and beginning to wonder whether my solutions are worse than nothing. When an SD card is inserted into a board that’s already powered on, a…
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