Mike Kranidis

Dear @Edzelf Pin 16 must be High in order to get OLED up and running. if you don't initialize then OLED is off.

I agree with you. The temporary low is just for reset as you already told. The only question left: Do you have any provision to pull up GPIO 16 High?...

Dear @Edzelf I am not sure how to connect VS1053 to HELTEC Dev board. Can you suggesting me the pin to pin connections? Thanks.

Yes you are right, I can confirm @Edzelf that the lines I put at void setup to set GPIO 16 not needed. Thanks

Dear @Edzelf My VS1053 has the following pinout: [VS1053 Module](https://www.aliexpress.com/item/VS1053-VS1053B-MP3-Module-For-Arduino-UNO-Breakout-Board-With-SD-Card-Slot-VS1053B-Ogg-Real/32816427942.html?spm=a2g0s.9042311.0.0.aKUqEs ) Pin.1 +5V Pin.2 GND Pin.3 CS Pin.4 MISO Pin.5 MOSI Pin.6 SCK Pin.7 XCS Pin.8 XRESET Pin.9 XDCS Pin.10...

Dear @Edzelf Many thanks. It is working fine now!