Supermicro PSU Monitor

Monitor Enterprise Supermicro Power Supplies on Consumer Hardware - No IPMI Required.

This project provides a complete monitoring solution for homelab enthusiasts running consumer motherboards (Asus, MSI, Gigabyte, etc.) inside enterprise Supermicro chassis (CSE-826, CSE-825, CSE-836, etc.).

Normally, these chassis communicate PSU telemetry to the server motherboard via a PMBus/I2C cable. Consumer boards lack this specific header. This project uses an inexpensive microcontroller (Arduino Nano, ESP32, etc.) to bridge that gap, reading real-time stats directly from the Power Distribution Board (PDB). You can preview data in Grafana, or simply in terminal.

🚀 Features

Hardware Monitoring

• Dual PSU Support: Continuous hot-swap monitoring for two PSUs.
• Real-Time Telemetry:
  • Thermals: Internal PSU temperature.
  • Cooling: RPM readings for Fan 1 and Fan 2.
  • Power: Input Voltage, Amperage, Wattage, and Load %.
  • Health: DC Good/Fail status.
• Plug & Play: Auto-detection logic instantly reports when a PSU is inserted, removed, or loses power.

Monitoring Stack

• Prometheus Exporter: Python-based exporter that reads JSON data from the microcontroller via serial and exposes Prometheus metrics.
• Docker Compose: Complete monitoring stack with Prometheus, Grafana, and Node Exporter.
• Pre-built Grafana Dashboard: Beautiful dashboard showing power consumption, temperature, voltage, and fan speeds.
• Automatic Staleness Detection: Metrics are automatically removed when a PSU is disconnected.

📋 Compatibility

Chassis & Backplanes

Tested and working with the PDB-PT826-8824 power distribution boards found in Supermicro CSE-826, but will probably work too with CSE-825 and CSE-836.

Power Supply Units (PSU)

Most Supermicro PSUs adhering to the PMBus 1.2 spec should work.

• Tested: PWS-920P-SQ, PWS-1K28P-SQ
• Likely Compatible: PWS-1K21P-1R, PWS-721P-1R, PWS-501P-1R and more

🛠️ Hardware Setup

Required Components

1. Microcontroller: Arduino Nano, ESP32, or compatible board
2. USB Cable: For connecting microcontroller to your server/monitoring system
3. Jumper Wires: 4 wires to connect to the PDB

Wiring

You need to connect to the SMBus/I2C header on the chassis Power Distribution Board (PDB). This is a small, dark, 5-pin header (with only 4 pins populated) located near the PSU slots.

PDB Wire Color	Signal	Arduino Nano Pin	Function
Yellow	SDA	A4	I2C Data Line
Green	SCL	A5	I2C Clock Line
Red	VCC	VIN	5V Power Source
Black	GND	GND	Ground

💻 Microcontroller Setup

1. Install PlatformIO

Follow the PlatformIO installation guide for your platform.

2. Configure Output Mode

The microcontroller supports two output modes in src/main.cpp:

// Human readable, or JSON for Prometheus
bool jsonOutputMode = true;  // Set to false for human-readable output

• JSON Mode (recommended): Outputs structured JSON for the Prometheus exporter
• Human-Readable Mode: Formated output for lightweight monitoring

3. Build and Upload

cd /path/to/Supermicro-PSU-monitor
pio run --target upload
pio device monitor

If you just want to monitor in terminal, that's all!

🐳 Monitoring Stack Setup

The complete monitoring stack runs in Docker and includes:

• Prometheus: Time-series database for metrics
• Grafana: Visualization and dashboards
• PSU Exporter: Custom exporter for PSU telemetry

Prerequisites

• Docker and Docker Compose installed
• Microcontroller connected via USB (typically /dev/ttyUSB0)
• Microcontroller flashed with firmware in JSON mode

Quick Start

1. Clone the repository:

git clone https://github.com/NasiadkaMaciej/Supermicro-PSU-monitor.git
cd Supermicro-PSU-monitor

2. Verify serial device:

ls -l /dev/ttyUSB*
# Should show /dev/ttyUSB0 or similar

3. Start the monitoring stack:

docker-compose up -d --build

4. Access the services:

• Grafana: http://localhost:3090 (default credentials: admin/admin)
• Prometheus: http://localhost:9090
• PSU Exporter: http://localhost:8000/metrics

Grafana Dashboard Setup

1. Log in to Grafana at http://localhost:3090

2. Add Prometheus as a data source:

   • Go to Configuration → Data Sources
   • Click "Add data source"
   • Select "Prometheus"
   • Set URL to http://prometheus:9090
   • Click "Save & Test"

3. Import the PSU dashboard:

   • Go to Dashboards → Import
   • Upload grafana/dashboards/psu-dashboard.json
   • Select the Prometheus data source
   • Click "Import"

Note: The Grafana dashboard automatically adjusts to show only connected PSUs. When a PSU is disconnected, it disappears from charts. The dashboard works seamlessly with both single and dual PSU configurations.

📊 Sample Output

JSON Mode (for Prometheus)

The microcontroller outputs one JSON object per PSU every 2 seconds:

{"id":1,"temp":54,"fan1":1488,"fan2":1488,"v_in":242.0,"i_in":0.31,"p_in":71,"ok":1}
{"id":2,"temp":53,"fan1":1603,"fan2":1488,"v_in":241.0,"i_in":0.31,"p_in":74,"ok":1}

Human-Readable

Set jsonOutputMode = false in src/main.cpp for formatted output:

Scenario: PSU #1 is not plugged in, then is connected, and power cable is attached

Supermicro PSU monitor
[2s] PSU #1: --- OFFLINE ---
[2s] PSU #2: 54C | 1488/1488 rpm | DC OK | 242V / 0.31A / 71W
[4s] PSU #1: --- OFFLINE ---
[4s] PSU #2: 54C | 1488/1374 rpm | DC OK | 242V / 0.31A / 71W
[6s] PSU #1: --- OFFLINE ---
[6s] PSU #2: 54C | 1488/1488 rpm | DC OK | 241V / 0.31A / 71W
[8s] PSU #1: --- OFFLINE ---
[8s] PSU #2: 54C | 1488/1488 rpm | DC OK | 241V / 0.31A / 70W
[10s] PSU #1: 20C | 0/0 rpm | FAULT | 0V / 0.00A / 0W
[10s] PSU #2: 53C | 1488/1488 rpm | DC OK | 241V / 0.31A / 71W
[12s] PSU #1: 20C | 0/0 rpm | FAULT | 0V / 0.00A / 0W
[12s] PSU #2: 54C | 1488/1488 rpm | DC OK | 241V / 0.31A / 74W
[14s] PSU #1: 21C | 229/229 rpm | FAULT | 255V / 0.00A / 3W
[14s] PSU #2: 53C | 1603/1603 rpm | DC OK | 241V / 0.31A / 74W
[16s] PSU #1: 21C | 1374/1030 rpm | DC OK | 243V / 0.00A / 46W
[16s] PSU #2: 53C | 1603/1603 rpm | DC OK | 250V / 0.31A / 74W
[18s] PSU #1: 21C | 1374/1030 rpm | DC OK | 244V / 0.37A / 46W
[18s] PSU #2: 53C | 1603/1488 rpm | DC OK | 244V / 0.12A / 18W

🧠 Technical Reference: Register Map

The code implements a lightweight subset of the Supermicro PMBus specification. Below is the reference map for the vendor-specific area should you wish to extend functionality:

Register	Description	Formula / Notes
0x09	Temperature	Direct value in °C
0x0A	Fan 1 Speed	RPM = (1/0.262) * (Raw * 30)
0x0B	Fan 2 Speed	RPM = (1/0.262) * (Raw * 30)
0x0C	Power Status	0x01 = DC Good, 0x00 = Failed
0x14	AC Current	Value / 16.0 = Amps (RMS)
0xF4	Input Voltage	Direct value in Volts (AC)
0xF5	Input Power (L)	Low Byte of 16-bit Wattage
0xF6	Input Power (H)	High Byte of 16-bit Wattage

Unused Registers for Potential Extension:

• 0x0D: Temp Limit (Temperature High Limit (°C))
• 0x0E: Fan 1 Min (Minimum Fan Speed Limit (Raw))
• 0x0F: Fan 2 Min (Minimum Fan Speed Limit Raw)
• 0x16: FW Version (Firmware Version (e.g., 0x21 = Rev 2.1))
• 0xF0: AC Limit (Max AC Current (Value / 16.0 = Max Amp))
• 0xF1: DC Limit (Max DC Current (Value / 2.0 = Max DC Amps))
• 0xF2: Rated Wattage (Low Byte of 16-bit word)
• 0xF3: Rated Wattage (High Byte of 16-bit word)
• 0xF5: Input Power (Low Byte of 16-bit Word (Watts))
• 0xF6: Input Power (High Byte of 16-bit Word (Watts))
• 0xFF: Write Protect (Write Protection Status)

🤝 Contributing

Contributions are welcome! Please feel free to submit issues or pull requests.

⚖️ License

MIT License. See LICENSE file for details.