I have a 150 led strip and the Spectrum daughter board and have been programming in sound responsive animations. Sound is fed into the Spectrum through a mini audio jack from my laptop. I’ve found though that if I start the Arduino (the script has been previously uploaded) without the usb link to my laptop connected then all the leds light up, and stay lit up: there’s some twinkling (that might be down to the blur function) but no detectable sound response. But as soon as I plug in the usb cable with the laptop it all starts working normally. If I remove the usb connector again the leds all light up.
The script (attached) does not need a serial connection, just the mini jack. I’ve remmed out the Serial.begin statement that I used for debugging as I went along, so there’s no dependence.
Why is this happening?
Thx