Psu controller

Wanptek PSU Digital Encoder & OLED Mod

A drop-in digital control upgrade for Wanptek bench DC power supplies that replace the stock, finicky analog potentiometers with digital rotary encoders, dual 12-bit DACs, and an OLED readout.

⚡ Overview

Stock Wanptek power supplies often ship with single-turn or coarse analog potentiometers that make dialling in exact voltage and current limits tedious and imprecise.

This mod replaces the analog control loop inputs with a microcontroller-driven interface, allowing precision stepping, fine/coarse toggling, quick voltage presets, and automatic EEPROM state recall.

Note on Hardware: This is my first-ever attempt at schematic and PCB design. While the layout might violate lots of standard PCB design rules, it is fully functional and tested on hardware. Contributions and layout improvements are welcome!

✨ Features

• Dual Rotary Encoder Control: Independent adjustment knobs for voltage and current.
• Coarse & Fine Modes:
  • Click the encoder buttons to switch between Coarse (1.0 V / 1.0 A) and Fine (0.05 V / 0.05 A) step increments.
  • Current status ([C] or [F]) shown directly on screen.
• Configurable Voltage Presets:
  • Long-press the voltage encoder to enter the Preset Menu.
  • Cycle through and load or overwrite custom presets saved directly to EEPROM.
• Auto-Save State: Automatically writes current setpoints to EEPROM 2 seconds after the last adjustment to prevent flash wear while preserving your settings across power cycles.
• OLED Interface: Clear 1.3" 128×64 display showing setpoints, active modes, and preset menus.
• Calibrated DAC Output: Linear scaling tailored for 0–32 V and 0–6.2 A output ranges.

🛠️ Hardware & Bill of Materials (BOM)

📐 Pinout Reference

Display (SPI)

• D10 ➔ OLED_CS
• D9 ➔ OLED_DC
• D8 ➔ OLED_RST
• D13 ➔ SCK / CLK
• D11 ➔ MOSI / DIN

I2C DACs

• A4 ➔ SDA (Shared bus, addresses configured via A0 pin: 0x60 for Voltage, 0x61 for Current)
• A5 ➔ SCL

Encoders

• Voltage: CLK ➔ D2, DT ➔ D3, SW ➔ D4
• Current: CLK ➔ D5, DT ➔ D6, SW ➔ D7

🔧 Software & Dependencies

Compile and flash using the Arduino IDE. Required libraries:

• Adafruit_GFX
• Adafruit_SH110X
• Adafruit_MCP4725
• Wire (Standard Arduino core)
• SPI (Standard Arduino core)
• EEPROM (Standard Arduino core)

Calibration Note

The DAC transfer functions inside updatePSU() are mapped to linear curves based on measured output data:

$$\text{DAC}V = 129.15 \times V{\text{target}} + 27.0$$ $$\text{DAC}A = 594.10 \times I{\text{target}} + 424.4$$

Adjust these constants in the sketch if your specific Wanptek model or reference voltages differ.

📂 Repository Structure

├── firmware/
│   └── psu_controller/
│       └── psu_controller.ino
├── hardware/
│   ├── gerbers/
│   ├── psu_controller.kicad_pro
│   ├── psu_controller.kicad_sch
│   └── psu_controller.kicad_pcb
└── README.md