What would it take to build an addressable LED like the WS2812 (aka Neopixel) using only discrete transistors? Time for a small “1960 style logic meets modern application” technology fusion project.Continue reading “The TransistorPixel”
Time for another project with a super-low-cost microcontroller. But what to design? Ever since seeing a project where a $0.03 MCU controls $40 worth of intelligent RGB LEDs, I have been wondering whether this is the right place to use these devices. At this price point, doesn’t it seem to make more sense to dedicate one MCU to one LED each and use it to implement a fancy node-controller? It has always appealed to me to design my own protocol. However, just copying a WS2812 RGB LED or similar seemed to be a bit pointless…Continue reading “Intelligent 7-Segment Display”
Two years ago I took a deeper look into the APA102. Although it was more expensive than the common WS2812, and harder to come by, it had some intriguing properties. The main benefits are a timing-insensitive SPI interface, allowing easy interfacing to standard periphery, and a much higher PWM frequency of >19kHz, making the APA102 almost flicker free.
So much about that. Considering how things with LEDs from China go, it should not take too long for clones to appear? Indeed! Recently, several comments showed up on my blog, reporting about issues with APA102 LEDs they bought. It quickly turned out that these were SK9822, APA102 clones from the same company that already brought the SK6812 to us, a WS2812 clone.
One of these people was Mike. He developed the Weblight, a WebUSB controlled RGB LED. The prototype (shown below, red pcb) worked well, but when he commissioned a small production run (black pcb), the LED started to show odd update behavior. Mike was nice enough to share a couple of boards with me for further investigation.