A Windows system tray application that sends CPU and memory utilization to a custom Arduino-based analog meter device.
PC Meter consists of two parts:
- Windows app (
PcMeter/) — a .NET 8 WPF tray application that reads CPU% and memory% every 500ms and sends the values to the meter device over a serial port. - Arduino firmware (
arduino/) — runs on an Arduino Leonardo, receives the data over serial, and drives two analog panel meters with green/red LEDs.
The meter hardware uses analog panel meters (VU-style gauges) driven by PWM output from the Arduino. Each meter has a green LED that switches to red when utilization exceeds 80%.
- Windows 10/11
- .NET 8 runtime (or SDK to build)
- Arduino-based PC Meter device connected via USB (virtual COM port)
dotnet build PcMeter/PcMeter.csproj
dotnet run --project PcMeter/PcMeter.csproj
Or open PcMeter/PcMeter.csproj in Visual Studio 2022.
The app runs as a system tray icon. Right-click the tray icon to:
- View live CPU% and Memory%
- Connect / disconnect the serial port
- Open Settings to choose the COM port
- View the About dialog
- Exit the application
On first run, go to Settings and select the COM port your Arduino is connected to. The setting is saved to %APPDATA%\PcMeter\settings.json and restored on next launch.
The app shows a balloon tip when it successfully connects to the device. If the device is unplugged while running, an error message is shown and the app continues running — reconnect via the tray menu.
| Setting | Default | Description |
|---|---|---|
| COM Port | COM20 | Serial port the Arduino is connected to |
- Arduino Leonardo (or compatible)
- Arduino IDE 1.8+ or 2.x
| Pin | Function |
|---|---|
| 11 | CPU meter (PWM) |
| 10 | Memory meter (PWM) |
| 4 | CPU green LED |
| 5 | CPU red LED |
| 2 | Memory green LED |
| 3 | Memory red LED |
- Meters update every 100ms, smoothed using a rolling average of 20 readings for fluid needle movement
- LEDs are green below 80% utilization and switch to red at or above 80%
- On startup, both meters sweep to 100% for 2 seconds as a self-test
- If no serial data is received for 2 seconds, a "screensaver" mode activates: needles sweep back and forth until data resumes
The Windows app sends CR-terminated messages at 9600 baud:
C{0-100}\r → CPU percentage
M{0-100}\r → Memory percentage
Both are sent together every 500ms: C42\rM67\r
PcMeter/ .NET 8 WPF tray application (current)
PcMeter (legacy)/ .NET Framework 4.8 WinForms app (legacy)
arduino/ Arduino firmware
drawings/ Meter face artwork (SVG + PNG)
MIT License — Copyright © 2018-2026 Scott W. Vincent