NeoMeter - ESP32-C3 Mechanical Gauge

Lightweight, quiet, fast-response mechanical gauge.

NeoMeter is a programmable mechanical gauge system that leverages the ESP32-C3 to drive analog needle meters (such as current gauges) using PWM-based voltage control.

This project can function in two modes:

1. Serial Mode (PC Monitoring) - Reads CPU, RAM, GPU, and VRAM utilization from a computer and maps them to 0-3V outputs to drive gauges.
2. Home Assistant Mode - Integrates with Home Assistant for smart home applications, allowing users to control gauge values via a UI.

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🛠️ Hardware

Recommended Analog Gauge Setup

• 5mA gauge
• Two 300Ω resistors in series
• Driven using ESP32-C3's PWM 0-3V output

Gauge Type	Connection
CPU Usage Meter	GPIO0
RAM Usage Meter	GPIO1
GPU Usage Meter	GPIO5
VRAM Usage Meter	GPIO21

Example Setup

Works well with 5mA gauges, using two 300Ω resistors in series to achieve 0-3V PWM control.

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1️⃣ Serial Mode (PC Monitoring)

Purpose: Reads system resource usage (CPU, RAM, GPU, VRAM) and maps the data to mechanical needle gauges using PWM.

💾 Setup (PC Side)

1. Install Dependencies

Run the following command to install required Python libraries:

pip install psutil serial gputil

2. Run the PC Monitoring Script

Modify SERIAL_PORT according to your system (COMx for Windows, /dev/ttyUSBx for Linux/macOS), then run:

python Serial_PCmon/pc_monitor.py

3. Expected Serial Output

Sent: 85,60,80,50;
Sent: 82,55,75,45;

• 85 → CPU Available (CPU Load = 15%)
• 60 → RAM Available
• 80 → GPU Available (GPU Load = 20%)
• 50 → VRAM Available

🔌 Wiring

PC Resource	ESP32-C3 GPIO	Gauge Label
CPU Load	GPIO0	CPU Gauge
RAM Usage	GPIO1	RAM Gauge
GPU Load	GPIO5	GPU Gauge
VRAM Usage	GPIO21	VRAM Gauge

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📡 ESP32-C3 Firmware (Serial Mode)

Upload sketch_feb22a.ino to ESP32-C3

Use Arduino IDE or PlatformIO to flash the firmware.

ESP32 Features

✅ Reads serial data (e.g., 85,60,80,50;) ✅ Maps 0-100% utilization to PWM (0-3V) ✅ Outputs PWM signals to control analog meters

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2️⃣ Home Assistant Mode (ESPHome)

Purpose: Allows gauge control through Home Assistant, integrating with smart home automation.

🏠 Home Assistant Integration

NeoMeter can be controlled remotely via Home Assistant UI sliders. The sliders adjust PWM output, setting the needle gauge position.

🔌 Wiring

Home Assistant Entity	ESP32-C3 GPIO	Gauge Label
voltage_control_gpio0	GPIO0	Gauge 1
voltage_control_gpio1	GPIO1	Gauge 2
voltage_control_gpio5	GPIO5	Gauge 3
voltage_control_gpio21	GPIO21	Gauge 4

⚙️ ESPHome Configuration (esp32-c3-gauge.yaml)

esphome:
  name: esp32-c3-gauge
  friendly_name: ESP32-C3-Gauge
  board: esp32-c3-devkitm-1
  platform: ESP32

wifi:
  ssid: !secret wifi_ssid
  password: !secret wifi_password
  ap:
    ssid: "ESP32-C3-Gauge Fallback"
    password: "backup123"

logger:

api:
  encryption:
    key: "lxETubxQ14a51dnMBCWvpFRJ5Ilswsv21MpEk9zAfCM="

ota:
  password: "439b3e036c6b235c7362e925fd92feb7"

number:
  - platform: homeassistant
    entity_id: input_number.voltage_control_gpio0
    id: ha_voltage_gpio0
    on_value:
      then:
        - lambda: |-
            float duty_cycle = x / 100.0;
            id(pwm_output_gpio0).set_level(duty_cycle);

  - platform: homeassistant
    entity_id: input_number.voltage_control_gpio1
    id: ha_voltage_gpio1
    on_value:
      then:
        - lambda: |-
            float duty_cycle = x / 100.0;
            id(pwm_output_gpio1).set_level(duty_cycle);

  - platform: homeassistant
    entity_id: input_number.voltage_control_gpio5
    id: ha_voltage_gpio5
    on_value:
      then:
        - lambda: |-
            float duty_cycle = x / 100.0;
            id(pwm_output_gpio5).set_level(duty_cycle);

  - platform: homeassistant
    entity_id: input_number.voltage_control_gpio21
    id: ha_voltage_gpio21
    on_value:
      then:
        - lambda: |-
            float duty_cycle = x / 100.0;
            id(pwm_output_gpio21).set_level(duty_cycle);

output:
  - platform: ledc
    pin: GPIO0
    frequency: 5000Hz
    id: pwm_output_gpio0

  - platform: ledc
    pin: GPIO1
    frequency: 5000Hz
    id: pwm_output_gpio1

  - platform: ledc
    pin: GPIO5
    frequency: 5000Hz
    id: pwm_output_gpio5

  - platform: ledc
    pin: GPIO21
    frequency: 5000Hz
    id: pwm_output_gpio21

🏠 Controlling the Gauge in Home Assistant

1. Open Home Assistant UI
2. Navigate to Developer Tools > States
3. Adjust the input_number.voltage_control_gpioX sliders

Each slider directly sets the PWM output level, controlling the gauge needle position.

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🛠️ Troubleshooting

Issue	Solution
No serial output in PC mode	Check SERIAL_PORT, ensure ESP32 is connected
Needle not moving	Verify PWM output voltage using a multimeter
Home Assistant not detecting	Check WiFi settings and ESPHome integration

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📌 Future Improvements

• WiFi Data Streaming - Stream PC resource usage over MQTT instead of Serial
• Multiple Meter Support - Expand to support more gauges with I²C DAC
• OLED Display - Show resource usage alongside gauges

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📢 Credits

💡 Author: Your Name 📅 Date: February 2025 🚀 Inspired by: Mechanical gauges & Home Automation

Enjoy your ESP32-C3-powered analog gauge! 🕹️⚙️📊