Compact DC Power Supply Supporting USB PPS, Using M5Stack

I would like to introduce an expansion board designed to stack onto the M5Stack Basic—featuring the "CH224A" chip from WCH (Nanjing Qinheng Microelectronics), which supports PPS (Programmable Power Supply) for continuously variable USB PD voltage—as well as a "USB PD analyzer" built using this board.

system diagram

The CH224A chip, which serves as the core USB PD PPS controller, interfaces with the M5Stack via I2C.

The system controls VBUS output by combining an ACS712xLCTR-05B (Allegro MicroSystems) for output current sensing with an AO4407 power MOSFET (Alpha & Omega) for output switching.

Additionally, a 5V supply—generated from the VBUS voltage using an HT2307A step-down DC-DC converter (HTCSEMI)—is connected directly to the +5V pin of the M5Stack Basic's internal M-BUS connector. This allows the device to operate simply by connecting to a USB charger, without relying on the M5Stack's standard connectors or internal battery.

PDO(Souece Capability) Decode

PD Fixed Voltage Control

PD PPS Control