Hello folks! In attempting to get sound reactivity working, I’m running into some noise issues with my mic + MSGEQ7. In short, I’m seeing a lot of additional high frequency noise when the LEDs are on. More specifically, I see this noise most prominently when outputting to a second strip on a second data channel, even when the total number of LEDs on is the same.
Some more details: I’m using an ESP8266 NodeMCU with a sparkfun MEMs mic (https://www.sparkfun.com/products/9868) and an MSGEQ7 for frequency analysis. The board and LEDs are all powered via 5V from the wall, and the mic+MSGEQ7 are powered from the 3V out of the ESP. I’ve tried a simple decoupling cap with 3V power from the ESP, and a “T-filter” (https://electronics.stackexchange.com/questions/306242/why-does-my-electret-microphone-amplifying-and-filtering-circuit-output-so-much) to clean up the power going into the mic+MSGEQ7, but neither have helped too much.
Below are two pictures of the issue. In the first, I am outputting to a single strip (GPIO5) of 240 LEDs. Blue is low frequencies, red is mids, green is highs. It’s noisier than when the LEDs are totally off, but it’s perfectly usable. The second picture is the same music but outputting to a second strip (GPIO4), each strip with 120 LEDs on (so same number of LEDs, same current draw). The mids and highs here are totally unusable, with a higher baseline.
It’s clear that there’s some PWM noise getting in when the LEDs are on, but I’m not sure why it changes when outputting to a second strip. If anyone has ideas on circuitry to eliminate the noise, or ideas on why this is happening, it would be greatly appreciated. Thank you!