The next version took some time to complete. From the initial concept, this is the third hardware version I designed. It has added an extra battery to enable standalone operation without the need to plug in a USB cable.

To power on or off the device, I utilized the AXP173 power management IC. This IC allows you to press and hold the power button to turn the device on or off. It manages power, charges the battery, and automatically switches between USB and battery power in a compact size (5x5mm), replacing multiple ICs for these tasks and saving PCB space.