TC66C Toolkit

A command-line toolkit for interacting with TC66/TC66C USB power meters. Read measurements, poll data continuously, retrieve recordings, and update firmware.

Disclaimer

This project has been 99.99% vivecoded and was not reviewed at all. It can and will contain bugs, and the UX might not be the best one. Use at your own risk.

The firmware update feature has been tested by myself on two devices, updating from versions 1.09 and 1.12 to 1.18, and also flashing 1.18 over a corrupted device (yes, the firmware update code didn't work on the first try) returning it to life, so it should be pretty safe to use.

Features

• Get readings: Single snapshot of voltage, current, power, and more
• Continuous polling: Monitor readings in real-time at configurable intervals
• Web UI: Browser-based interface with real-time graphing and monitoring
• Recording retrieval: Download stored measurement data from the device
• Firmware updates: Flash new firmware to your device (bootloader mode)
• JSON output: Export data in JSON format for scripting and analysis
• Cross-platform: Works on Linux, macOS, and Windows

Installation

From Source

Requires Go 1.25 or later:

git clone https://github.com/skgsergio/tc66c-toolkit
cd tc66c-toolkit
go build -o tc66c-toolkit ./cmd/toolkit

Usage

Basic Commands

Get a Single Reading

# Basic reading
tc66c-toolkit get

# JSON output
tc66c-toolkit get --json

# Custom serial port
tc66c-toolkit get -p /dev/ttyUSB0

Continuous Polling

# Poll every 500ms (default)
tc66c-toolkit poll

# Poll every second
tc66c-toolkit poll -i 1s

# Poll with JSON output
tc66c-toolkit poll --json

Web UI

Start a web server with a browser-based interface for real-time monitoring:

# Start web server (default: localhost:8080)
tc66c-toolkit web

# Custom address and port
tc66c-toolkit web -a 0.0.0.0 -w 8080

Then open your browser to http://localhost:8080. The Web UI provides:

• Serial port detection: Automatically lists available serial ports
• Real-time graphing: Dual Y-axis charts with configurable metrics
• Live readings: Display of voltage, current, power, temperature, and more
• Configurable polling: Adjustable intervals from 100ms to 2s
• WebSocket updates: Efficient real-time data streaming

Retrieve Recordings

tc66c-toolkit recording

Update Firmware

Warning: Only use firmware files from trusted sources.

# Enter bootloader mode first:
# 1. Unplug the device
# 2. Press and hold K1 button
# 3. Plug in the device while holding K1
# 4. Release K1

tc66c-toolkit update -f firmware.bin

Global Flags

• -p, --port: Serial port device path (default: /dev/ttyACM0)
• -h, --help: Show help

Command-Specific Flags

poll:

• -i, --interval: Polling interval (default: 500ms)
• -j, --json: Output in JSON format

get:

• -j, --json: Output in JSON format

web:

• -a, --address: Address to bind the web server (default: localhost)
• -w, --web-port: Port for the web server (default: 8080)

update:

• -f, --file: Firmware file (required)

Output Formats

Text Format (Default)

Product: TC66
Version: 1.14
Serial: 12345678
Runs: 42
Voltage: 5.1234 V
Current: 0.51234 A
Power: 2.6234 W
Resistance: 10.00 Ω
Group 0: 1234 mAh / 5678 mWh
Group 1: 2345 mAh / 6789 mWh
Temperature: 25.0 °C
D+ Voltage: 2.75 V
D- Voltage: 2.75 V

JSON Format

{"product":"TC66","version":"1.14","serial_number":12345678,"num_runs":42,"voltage":5.1234,"current":0.51234,"power":2.6234,"resistance":10.00,"group0_mah":1234,"group0_mwh":5678,"group1_mah":2345,"group1_mwh":6789,"temperature_sign":0,"temperature":25.0,"dplus_voltage":2.75,"dminus_voltage":2.75}

Library Usage

The toolkit can also be used as a Go library:

package main

import (
    "fmt"
    "github.com/skgsergio/tc66c-toolkit/lib/tc66c"
)

func main() {
    device, err := tc66c.NewTC66C("/dev/ttyACM0")
    if err != nil {
        panic(err)
    }
    defer device.Close()

    reading, err := device.GetReading()
    if err != nil {
        panic(err)
    }

    fmt.Printf("Voltage: %.4f V\n", reading.Voltage)
    fmt.Printf("Current: %.5f A\n", reading.Current)
    fmt.Printf("Power: %.4f W\n", reading.Power)
}

Troubleshooting

Permission Denied on Linux

Add your user to the dialout group:

sudo usermod -a -G dialout $USER

Then log out and back in.

Alternatively, run with sudo (not recommended for regular use).

Device Not Found

Check which port your device is on:

# Linux
ls /dev/ttyACM* /dev/ttyUSB*

# macOS
ls /dev/cu.usbmodem*

# Windows
# Check Device Manager for COM ports

Then specify the port:

tc66c-toolkit get -p /dev/ttyUSB0  # or COM3 on Windows

Protocol

The communication protocol is based on the sigrok project's TC66C protocol documentation. The device uses:

• Baud rate: 115200
• Data bits: 8
• Parity: None
• Stop bits: 1

All measurement data is AES-ECB encrypted with a static key.

License

Licensed under The "Better Ask The LLM" License (BATL) - Software offered "as is, maybe" with no warranties or guarantees. Use at your own risk, and when in doubt, better ask the LLM!

See LICENSE.md for details.