hardware-meter is a classical analog gauge that shows a hardware usage. It is a simple analog voltmeter with a microprocessor. Any MCU with USB serial communication and PWM GPIO could be used.
cpu-meter.mp4
Supported OS:
- Windows
- MacOS
- Linux (Not tested yet)
Supported metrics:
- CPU Utilization
- CPU Frequency
- Memory Utilization
- Swap Utilization
- Networks Speed
CPU temperature, disk metrics and GPU metrics will supported in the future.
Any MCUs like Arduino(ATmega), STM32 and ESP32 with USB and PWM could be used.
- Any MCU with USB serial and PWM output
- An analog voltmeter
Note
Arduino(ATmega) must have u# in its chip name (ex. ATmega32u4), which means on-chip USB support.
STM32 series have too many variants to explain here. Take a look at their catalog and choose a chip with USB peripheral.
Provided firmwares are for STM32F103C8T6 and STM32F407VET6.
On ESP32 series, ESP32-S2, ESP32-S3, ESP32-C3, ESP32-C6, ESP32-H4 are supported.
Plain ESP32 and ESP32-C2 is not supported since there is no USB peripheral.
Tip
There are common analog panel meters called 85C1 and 91C4 series, which cost only $2~3 and have a various voltage range. There are 0-3V and 0-5V models, which fit with most common MCUs.
Choose a voltage range by your MCU's logic level. 5V MCUs such as Arduino can manipulate both 0-5V and 0-3V models. 3.3V MCUs such as ESP32 or STM32, Raspberry Pi, etc. can only run 0-3V models.
If you write your own MCU code instead of using provided firmwares, please read followings carefully:
Important
If you are using a 5V MCU with a 0-3V voltmeter, the PWM output must be regulated to 3V max. If your MCU is 3.3V, it is recommended to adjust the PWM voltage to a max 3V, not 3.3V.
Important
If you use a 0-5V range voltmeter, please keep in mind that the PWM output voltage could be lower than 5V depending on your PC and MCU.
If your PC supplies a voltage less than 5V to the MCU via the USB, the MCU can only output that voltage to its PWM pin.
Also, most MCUs have a protection diode on their USB input, which makes additional VCC voltage drop. Mostly 0.3V (Schottky diode) or 0.7V (general diode).
This will result in the analog gauge not pointing its max position, even if the metric is pointing 100%. For example, if your PC supplies 4.7V and a protection diode drops 0.7V, the gauge will point 4V position even if the CPU is in full load.
- Connect the voltmeter and the MCU. Test your voltmeter's polarity with some batteries before connect with MCU.
+terminal goes to the PWM supported GPIO pin, and-terminal goes to the GND.
- Upload a firmware in
devices/*to your MCU.
| Supported MCU | PWM pin | Voltmeter range |
Note | Implementation |
|---|---|---|---|---|
| Arduino | D3 | 0-5V | Arduino IDE project (*.ino) | 4255dcc |
| STM32F4 | PA8 | 0-3V | STM32CubeIDE project ( STM32F407VET6) |
7c3e3a1 |
| STM32F1 | PA8 | 0-3V | STM32CubeIDE project ( STM32F103C8T6) |
265403c |
Note
If there is no firmware for your MCU, please implement and contribute your own!
It is just a basic program that reads 4 bytes little-endian float value from the serial and makes corresponding PWM output.
Optional:
- Build a 3d printed housing with 3d models at
3d models/*
- Download a latest desktop program at Releases.
- Connect your MCU and PC with a USB cable.
- Run your desktop executable. The tray icon will be generated.
- Click the tray icon and select your MCU's serial port.
Note
The list of the ports will be only scanned at the program launch.
This is a limit of tray-item-rs as their tray items are not editable or removable.
Tip
You can build a desktop program on your own by running cargo build --release.
If you are good at soldering, something like this is possible:
This is a hardware-meter with a USB Type-C port. All components including MCU and the Type-C port is mounted inside voltmeter.
The Arduino Pico runs 0-5V 85C1 voltmeter. USB Micro port on the Pico is desoldered and jumped onto a DIY Type-C board at the back side.