I put a small improvement on PHAP firmware. The case of initial firmware, everytime switching ON, display is initialised as analog meter mode. But if you prefer oscilloscope mode, it is something annoying everytime pushing button several times for switching ON. Now I put small modification that, the last state of display mode before switch OFF is memorised in EEPROM, and next time of switching ON, PHAP will start as the previous state. The Arduino sketch is uploaded to my github account.

Fortunately I finished this modification before tindie store's approval and all of shipment will be with this modified firmware. You can buy PHAP semi-kit at

https://www.tindie.com/products/microwavemont/pretty-happy-amplifier-phap--class-d-with-oled/

, and actual operation can be found in the following movie...!