Add a power sensor

Add a power sensor to your machine’s configuration so you can monitor voltage, current, and power consumption from the Viam app and from code.

Concepts

A power sensor component provides three methods:

• GetVoltage: voltage in volts and whether it’s AC or DC.
• GetCurrent: current in amperes and whether it’s AC or DC.
• GetPower: power in watts.

Built-in models

Additional models are available as modules in the Viam registry.

Steps

1. Prerequisites

• Your machine is online in the Viam app.
• A board component is configured (for I2C communication).
• Your power sensor is wired: I2C data and clock lines to the board, power measurement lines in the circuit you want to monitor.

2. Add a power sensor component

1. Click the + button.
2. Select Configuration block.
3. Search for the power sensor model that matches your hardware. Search by chip name (for example, ina219, ina226).
4. Name it (for example, battery-monitor) and click Create.

3. Configure attributes

INA219 example:

{
  "board": "my-board",
  "i2c_bus": "1",
  "i2c_address": 64
}

4. Save and test

Click Save, then expand the Test section.

• The test panel shows voltage, current, and power readings.
• Verify the voltage matches what you expect from your power supply or battery.

Try it

Read voltage, current, and power programmatically.

To get the credentials for the code below, go to your machine’s page in the Viam app, click the CONNECT tab, and select API keys. Copy the API key and API key ID. Copy the machine address from the same tab. When you run the code below, you’ll see voltage, current, and power readings. Verify the voltage matches your power supply.

pip install viam-sdk

import asyncio
from viam.robot.client import RobotClient
from viam.components.power_sensor import PowerSensor


async def main():
    opts = RobotClient.Options.with_api_key(
        api_key="YOUR-API-KEY",
        api_key_id="YOUR-API-KEY-ID"
    )
    robot = await RobotClient.at_address("YOUR-MACHINE-ADDRESS", opts)

    sensor = PowerSensor.from_robot(robot, "battery-monitor")

    voltage, is_ac = await sensor.get_voltage()
    print(f"Voltage: {voltage:.2f}V ({'AC' if is_ac else 'DC'})")

    current, is_ac = await sensor.get_current()
    print(f"Current: {current:.3f}A ({'AC' if is_ac else 'DC'})")

    power = await sensor.get_power()
    print(f"Power: {power:.2f}W")

    await robot.close()

if __name__ == "__main__":
    asyncio.run(main())

python power_sensor_test.py

Voltage: 12.34V (DC)
Current: 0.567A (DC)
Power: 6.99W

mkdir power-sensor-test && cd power-sensor-test
go mod init power-sensor-test
go get go.viam.com/rdk

package main

import (
    "context"
    "fmt"

    "go.viam.com/rdk/components/powersensor"
    "go.viam.com/rdk/logging"
    "go.viam.com/rdk/robot/client"
    "go.viam.com/rdk/utils"
)

func main() {
    ctx := context.Background()
    logger := logging.NewLogger("power-sensor-test")

    robot, err := client.New(ctx, "YOUR-MACHINE-ADDRESS", logger,
        client.WithCredentials(utils.Credentials{
            Type:    utils.CredentialsTypeAPIKey,
            Payload: "YOUR-API-KEY",
        }),
        client.WithAPIKeyID("YOUR-API-KEY-ID"),
    )
    if err != nil {
        logger.Fatal(err)
    }
    defer robot.Close(ctx)

    sensor, err := powersensor.FromProvider(robot, "battery-monitor")
    if err != nil {
        logger.Fatal(err)
    }

    voltage, isAC, err := sensor.Voltage(ctx, nil)
    if err != nil {
        logger.Fatal(err)
    }
    acdc := "DC"
    if isAC {
        acdc = "AC"
    }
    fmt.Printf("Voltage: %.2fV (%s)\n", voltage, acdc)

    current, isAC, err := sensor.Current(ctx, nil)
    if err != nil {
        logger.Fatal(err)
    }
    acdc = "DC"
    if isAC {
        acdc = "AC"
    }
    fmt.Printf("Current: %.3fA (%s)\n", current, acdc)

    power, err := sensor.Power(ctx, nil)
    if err != nil {
        logger.Fatal(err)
    }
    fmt.Printf("Power: %.2fW\n", power)
}

go run main.go

Troubleshooting

What’s next

• Power sensor API reference: full method documentation.
• Capture and Sync Data: log power consumption over time.
• What is a module?: write a module that alerts on low battery or high current draw.