A Go library and command-line tool for reading power samples (voltage and current) from compatible USB power meter devices (e.g., WITRN C4/C5 meters) via USB HID.

• Reads real-time voltage and current samples from supported USB power meters
• Outputs samples in JSON format (optional)
• Computes and displays statistics (min, max, average, percentiles) for voltage and current
• Supports sampling for a specified duration

• Go 1.18 or newer
• Compatible USB power meter (e.g., WITRN)
• macOS, Linux, or Windows

Clone the repository and build the command-line tool:

git clone <this-repo-url>
cd usbpower
cd cmd/usbpower
go build -o usbpower

./usbpower [flags]

• -duration <duration>: Stop sampling after the specified duration (e.g., 10s, 1m). If not set, runs until interrupted.
• -output json: Output each sample as a JSON object to stdout.

Sample for 10 seconds and print statistics:

./usbpower -duration 10s

Sample for 5 seconds and output raw JSON samples:

./usbpower -duration 5s -output json

After sampling, the tool prints statistics for voltage and current:

• Minimum
• Maximum
• Average
• 50th percentile (median)
• 90th percentile

You can use the usbpower package in your own Go programs to access USB power meter data:

import "github.com/rs/usbpower"

device, err := usbpower.OpenDevice()
if err != nil {
    // handle error
}
defer device.Close()
sample, err := device.Read()
// use sample.Voltage, sample.Current, sample.Timestamp

MIT