PD240W

An adjustable power supply for motor drives using USB-C Power Delivery negotiation, supporting up to 240W at 48V 5A. Firmware runs on a Raspberry Pi Pico (RP2040).

Features

• USB-C Power Delivery: Negotiates Fixed, PPS (5-21V programmable), and AVS (15-48V EPR) profiles
• Current Limiting: Adjustable 50mA-5A via INA228 power monitor with hardware overcurrent protection
• LCD Interface: 240x320 ST7789 display with anti-aliased fonts and Prusa-style encoder navigation
• Safety: Overcurrent ISR, overtemperature monitoring (NTC + INA228)
• Settings Persistence: User settings stored in RP2040 flash with CRC32 validation
• Auto PPS Tuning: Closed-loop voltage correction for PPS charger output accuracy
• Energy Monitoring: Tracks mAh delivered since boot via INA228 charge accumulator
• 17V Buck Output: Optional STO/SBC voltage for motor drive safety circuits
• Configurable: Brightness, auto-dim, startup melody, auto-output on boot

Hardware

Component	Part	Specification
MCU	Raspberry Pi Pico (RP2040)	Dual Cortex-M0+, 264KB SRAM
USB-C PD Controller	TI TPS26750	I2C 0x21, USB PD 3.1 with EPR
Current Sensor	TI INA228	I2C 0x40, 8mOhm shunt, 20-bit
Display	ST7789	240x320 2.4" SPI @ 10MHz
RGB LED	SK6812	PIO driven, GRB color order
Input	Rotary encoder + 2 buttons	ISR-based with debounce
Buzzer	PWM driven	Configurable melodies
Max Output		48V @ 5A (240W)

Hardware Files

Type	Path	Contents
PCB (STEP)	3D_models/PD240W_PCB.stp	Full PCB 3D model
Enclosure (STL)	3D_models/enclosure/	Casing top/bottom, knob, button, LCD support, SWD cover
Gerbers	PCB_files/gerbers/	PCB manufacturing files
BOM	PCB_files/BOM.csv	Bill of materials

Pin Map

Bus	Pins	Peripherals
I2C0 @ 400kHz	GP4/GP5	INA228, TPS26750
I2C1 @ 400kHz	GP14/GP15	CAT24C512 EEPROM (TPS26750 config)
SPI	GP18-GP21	ST7789 LCD
UART @ 115200	GP16 TX / GP29 RX	Debug serial output
PWM	GP24	LCD backlight
PIO	GP28	SK6812 RGB LED

Quick Start

Flash Pre-built Firmware

1. Download PD240W.uf2 from the latest release
2. Hold BOOTSEL button on the Pico while connecting USB
3. Drag PD240W.uf2 to the mounted RPI-RP2 drive

Build from Source

Requires: Pico SDK 2.2.0, ARM GCC toolchain, CMake, Ninja

git clone https://github.com/theohg/PD240W.git
cd PD240W

mkdir -p build && cd build
cmake -G Ninja ..
ninja

The output binary is build/PD240W.uf2.

Flash via SWD

openocd -f interface/cmsis-dap.cfg -f target/rp2040.cfg \
  -c "adapter speed 5000; program build/PD240W.elf verify reset exit"

Controls

Input	Action
Encoder Rotate	Navigate menus / Adjust values
Encoder Click	Confirm / Select
Encoder Long Press	Go Back / Exit current screen
BTN1	Toggle load switch output
BTN2	Toggle 17V buck (requires VBUS > 18V)

Menu Structure

graph TD
  %% Nodes
      Boot([Boot]) -->|≤2s| Main[Main Screen]
      Main -->|Error| Fault[Fault Screen]
      Fault -->|Click| Main
      
      Main <-->|Click| Menu[Main Menu]

      Menu --> Voltage[Select Voltage]
      Menu --> Current[Current Limit]
      Menu --> Settings[Settings]
      Menu --> About[About]

      Voltage <-->|Select PDO| AdjV[Adjust Voltage]
      Current <-->|Set Limit| AdjC[Adjust Current]
      
      Settings --> EEPROM[Flash EEPROM]
      Settings --> Configs[Params: Brightness / Sounds / Tuning...]
      
      %% Styling
      classDef default fill:#f9f9f9,stroke:#333,stroke-width:1px;
      classDef alert fill:#ffcccc,stroke:#cc0000,stroke-width:2px;
      class Fault alert;

Loading

Menu Item	Description
Select Voltage	Fixed / PPS / AVS PDO selection
Current Limit	50mA - 5A, 50mA steps with encoder acceleration
Flash EEPROM	TPS26750 configuration flash workflow
Auto PPS Tuning	Closed-loop voltage correction (ON/OFF)
Auto Output	Enable load switch on boot (ON/OFF)
Brightness	LCD backlight 5-100%
Dim Timeout	Auto-dim after 1-10 min inactivity
Startup Melody	Silent / Mario / Chime / TwoTone
Sounds	Navigation beeps (ON/OFF)

Project Structure

src/
├── main.cpp                        Entry point, non-blocking main event loop
├── hardware.h/cpp                  Hardware singleton aggregating all drivers
├── interrupts.h/cpp                Centralized GPIO interrupt router (RP2040 single-callback)
│
├── config/
│   ├── board_config.h              Pin definitions (Board:: namespace)
│   ├── app_config.h                Timeouts, thresholds, limits (AppConfig:: namespace)
│   └── version.h                   Firmware & hardware version, author...
│
├── drivers/                        Low-level hardware drivers (no business logic)
│   ├── display/
│   │   ├── st7789.h/cpp            SPI LCD driver with AA font rendering
│   │   ├── aa_font.h               Anti-aliased font data structure
│   │   └── font_inter_*.h          Generated Inter font bitmaps (14/20/28px)
│   ├── power/
│   │   ├── ina228/                 Power monitor: voltage, current, power, temperature
│   │   └── tps26750/               USB-PD controller: PDO discovery, contract negotiation
│   ├── input/
│   │   ├── rotary_enc.h/cpp        Quadrature encoder with velocity tracking
│   │   ├── button.h/cpp            Debounced button with click/long-press
│   │   └── adc_inputs.h/cpp        VBUS voltage + NTC temperature (ADC channels)
│   ├── gpio/                       SimpleIO: digital output with non-blocking blink
│   ├── buzzer/                     PWM buzzer with melody playback
│   └── rgb_led/                    SK6812 via PIO state machine
│
├── logic/                          Application logic
│   ├── state_machine.h/cpp         BOOT -> MAIN <-> MENU <-> ADJUST, FAULT handling
│   ├── safety.h/cpp                Temperature/voltage/current monitoring, fault triggers
│   ├── pd_manager.h/cpp            PD contract caching, PPS keep-alive, auto-tuning
│   ├── settings.h/cpp              Flash persistence with CRC32, debounced saves
│   └── tps_eeprom_workflow.h/cpp   TPS26750 EEPROM compare/flash state machine
│
├── ui/
│   ├── display_manager.h/cpp       All screen rendering (boot, main, menu, adjust, fault)
│   ├── font_config.h               Central font size mapping (FONT_LARGE/MEDIUM/SMALL)
│   └── assets/synapticon_logo.h    Boot screen logo bitmap
│
├── utils/
│   ├── logging.h                   LOG_INFO/WARN/ERROR/DEBUG/CRITICAL macros
│   ├── tps_eeprom_loader.h/cpp     Low-level TPS26750 EEPROM read/write
│   └── tps26750_patch.c            TPS26750 binary configuration blob
│
└── tools/
    ├── generate_font.py            Font bitmap generator (Python + Pillow)
    └── fonts/                      Source TTF files (Inter)

Author

Theo Heng - Synapticon GmbH

Acknowledgements

This project was made possible by Synapticon GmbH, who funded and supported its development. Thank you for providing the resources, hardware, and opportunity to bring PD240W to life.