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Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
@HaraldK
I got a nice STM32F4 Discovery board for quite a while. Recently installing Espruino (1v80) on it and having a significant amount of fun learning JavaScript. But now I got an electronical problem (unlikely Espruino, but maybe STM32 related):
See here
for what happens.
Connections: STM32F4 board connecting to PC (for terminal) and a LiPo and switched regulator to the 5V input. B15 is connected via a jumper cable to Din of the WS2812 chain. GND too. Vcc of the LEDs is not using 5V as that gives me those high intensity colors I get too when I touch the LiPo. So I know that 3.3V is not sufficient to drive a 5V WS2812. Fine. No issue. I should drive it with 5V after all.
The problem is that I'd like to understand the mechanism why when I touch the LiPo, the light intensity is reproduceable different. It's still working as sending data to the WS2812 still makes the lights move in circles. The colors change:
Low intensity blue gets high intensity red. High intensity blue gets low intensity green.
Low intensity red get high intensity green. High intensity red gets black.
My understanding of R and C and transient spikes cannot explain this at all. The WS2812 is after all a digital device.
Anyone an idea what happens?
I know the fix is to drive the WS2812 with 5V, or drive them with 3.3V and have Vcc on the WS2812 get 3.3V (or less than 3.8V). That's not the problem. I'd like to understand why those LEDs behave odd when I touch the LiPo.