Hey, the LEDs are not connected to RPI GPIO, they’re connected to a microcontroller on Pisound which is in charge of MIDI communication. You can flash the LEDs for variable duration by doing what this script does: https://github.com/BlokasLabs/pisound/blob/master/scripts/common/common.sh#L38
Best way to use it is to ‘include’ it from your scripts and call the flash_leds function, something like this:
. /usr/local/pisound/scripts/common/common.sh # This imports the common.sh
Only the button GPIO might be useful to know, the rest of the used pins are used for internal functions of the Pisound board, like resetting the codec, selecting the sampling rate, communication via SPI bus, audio via I2S pins, etc… All of that is taken care of by the Pisound kernel module, and it wouldn’t be useful to access those pins from user space code.