Mini power

Mini-Power

Mini-Power is a small, portable DC power supply unit designed to provide a convenient and reliable source of adjustable voltage for your electronic devices and breadboard experiments. Powered from a USB Power Delivery (PD) charger, it supports both Standard Power Range (SPR) and Extended Power Range (EPR) modes, making it perfect for electronics developers, students, and anyone who needs a compact bench power supply.

Key Features

• Easy access to the breadboard: both sides accessible via standard 2.54mm pitch pin headers.
• USB PD support: 5V to 28V output using the AP33772S PD Sink Controller.
• Variable voltage: 0.1V steps using PPS APDO, with automatic fallback to the nearest Fixed PDO.
• Real-time display: SSD1306 128×64 OLED showing output voltage, measured voltage, current, power, WiFi status, and buffer usage.
• Data logging: Measurements sent to InfluxDB over WiFi (InfluxDB Line Protocol, HTTPS).
• Remote syslog: RFC 5424 over UDP for monitoring and troubleshooting.
• HTTP web interface: Real-time graphs (Chart.js), voltage control, and output ON/OFF toggle from any browser on the local network.
• Three-button interface: Up / Down / Center push buttons for direct voltage adjustment and output control.
• NVS persistence: Last voltage setting is saved to flash and restored on reboot.
• Safety protections: OVP, UVP, OCP (in AP33772S hardware) plus software current/power limits and voltage overshoot detection (>110% of setpoint).

Hardware Components

Schematic and PCB files are in the hardware/ directory. The board is designed with KiCad. A PDF export of the schematic is available at hardware/schematic.pdf.

The ap33772s-driver crate is used for all USB-PD communication with the AP33772S controller.

Software Architecture

The firmware is written entirely in Rust using the ESP-IDF framework.

How to Use the Unit

Basic Operation

1. Connection: Connect a USB-C PD charger*1 to the input port.
2. Power On: The unit negotiates PD profiles and scrolls through the available PDO list on the display.
3. Main Screen: After getting a IP address from DHCP server*2, the display shows output voltage, current, power, WiFi RSSI, IP address(last two octets)and buffer usage.
4. Voltage Selection: Press Up(yellow) or Down(blue) to increase/decrease the target voltage in 0.1V steps.
5. Output Control: Press Center(red) to toggle output ON/OFF.
6. Monitoring: View real-time measurements on the OLED display or open http://<device-ip>/ in a browser.

Note *1: When it doesn't connect to the PD charger, the display will show "No PD Power". Click the up/down buttons to show main screen. It only can output 5V. *2: If it can't connect to WiFi, the display will show the main screen after 30 seconds, but without IP address and RSSI.

Button Controls

OLED Display

The SSD1306 128×64 monochrome OLED display is divided into several regions as shown below.

Startup sequence:

1. At boot, the PDO list screen is shown first — all Power Data Objects negotiated with the charger are listed (voltage, current, max power, type). Each page is shown for 3 seconds.
2. After PDO display completes, the main screen appears.
3. Error / warning messages (e.g. Voltage Overshoot, Current OV x.xxxA) replace the main screen temporarily and auto-dismiss after 3 seconds.

HTTP Web Interface

When connected to WiFi, open http://<device-ip>/ (IP shown on OLED display) to access:

• Live voltage, current, and power readings updated every second
• Real-time voltage and current graph (Chart.js)
• PDO table showing all available power profiles from the charger
• Voltage control with +/− buttons (0.1V step)
• Output ON/OFF toggle

Safety Protections

How to Build from Code and Install to the Unit

Using Ubuntu 22.04 LTS

1. Install Rust Compiler

sudo apt update && sudo apt -y install git python3 python3-pip gcc build-essential \
  curl pkg-config libudev-dev libtinfo5 clang libclang-dev llvm-dev udev libssl-dev python3.10-venv nano

curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
# Select option 1 (default install)

source "$HOME/.cargo/env"

2. Install toolchain for ESP32-C3

cargo install ldproxy
cargo install cargo-binstall
cargo install espup
espup install
espup update
. ./export-esp.sh
cargo binstall cargo-espflash

3. Add UDEV rules

sudo sh -c 'echo "SUBSYSTEMS==\"usb\", ATTRS{idVendor}==\"303a\", ATTRS{idProduct}==\"1001\", MODE=\"0666\"" \
  > /etc/udev/rules.d/99-esp32.rules'
sudo udevadm control --reload-rules
sudo udevadm trigger

4. Clone the repository

git clone https://github.com/hnz1102/mini-power.git
cd mini-power/code

5. Configure WiFi and InfluxDB

cp cfg.toml.samp cfg.toml
nano cfg.toml

[mini-power]
wifi_ssid = "YOUR_WIFI_SSID"
wifi_psk = "YOUR_WIFI_PASSWORD"
influxdb_server = "192.168.x.x:8086"
influxdb_api_key = "<YOUR_API_KEY>"
influxdb_api = "/api/v2/write?org=<ORG>&bucket=LOGGER&precision=ns"
influxdb_measurement = "minipower"
influxdb_tag = "ch"
max_current_limit = "5.2"
max_power_limit = "100.0"
max_temperature = "75"
syslog_server = "192.168.x.x:514"
syslog_enable = "false"

6. Connect the board and verify

cargo espflash board-info
# Select /dev/ttyACM0
# Expected: Chip type: esp32c3, Flash size: 4MB

7. Build and flash

cargo espflash flash --release --monitor

The device boots automatically after flashing. The OLED display will show the PDO list negotiated with the charger, then switch to the main monitoring screen.

How to Install InfluxDB and Configure the Dashboard

1. Download and install InfluxDB

wget https://dl.influxdata.com/influxdb/releases/influxdb2-2.7.0-amd64.deb
sudo dpkg -i influxdb2-2.7.0-amd64.deb
sudo service influxdb start

2. Initial configuration

Open http://<server-ip>:8086. Click GET STARTED and set:

3. Get the API Token

Copy the Operator API Token shown after setup — you will not see it again. To generate a new token later: API Tokens → GENERATE API TOKEN → All access token.

4. Import the Dashboard Template

Click Dashboard → CREATE DASHBOARD → Import Dashboard. Drop the influxdb/mimi-power.json file into the import dialog, then click IMPORT JSON AS DASHBOARD.

You will see the Mimi-POWER dashboard. It contains three time-series graphs:

All charts query the LOGGER bucket, measurement minipower, tag tag = "ch".

5. Start logging

Enable the output on the Mini-Power unit (Center button or web interface). Measurement data will be sent to InfluxDB and appear on the dashboard in real-time.

Schematic and PCB Data

The PCB is designed with KiCad. All hardware design files are in the hardware/ directory.

3D Printed Enclosure

The enclosure design files are in the hardware/Container/ directory.

All parts are designed for FDM 3D printing. Print body.3mf, upper.3mf, and three copies of button.3mf.

License

This source code is licensed under MIT. Other Hardware Schematic documents are licensed under CC-BY-SA V4.0.