INA219 Current / Voltage Sensor for micro:bit (MakeCode)

This MakeCode extension adds support for the Adafruit INA219 current and power sensor breakout board. (https://www.adafruit.com/product/904)

It allows a micro:bit to measure:

• Bus voltage (V)
• Shunt voltage (mV)
• Current (mA)
• Power (W)

Designed for classroom experiments with motors, turbines, batteries, and general electrical investigations.

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Hardware

Tested with the Adafruit INA219 breakout (default I2C address: 0x40).

Typical shunt resistor on the breakout: 0.1Ω

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Wiring

micro:bit	INA219
3V	VCC
GND	GND
P19	SCL
P20	SDA

The micro:bit uses I2C on pins P19 (SCL) and P20 (SDA).

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Installing the Extension

1. Open MakeCode for micro:bit.
2. Create a new project.
3. Click Extensions.
4. Paste this repository’s GitHub URL.
5. Add the extension.

You will see a new INA219 category in the Blocks menu.

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Basic Example

INA219.begin(0x40, 0.1)

basic.forever(function () {
    serial.writeLine("Voltage (V): " + INA219.busVoltage_V())
    serial.writeLine("Current (mA): " + INA219.current_mA())
    serial.writeLine("Power (W): " + INA219.power_W())
    serial.writeLine("---")
    basic.pause(500)
})

Open the Serial console in MakeCode to view measurements.

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Calibration Notes

Default configuration assumes:

• 0.1Ω shunt resistor
• Approximately 3.2A maximum range
• 100µA current resolution

If using a different shunt resistor value:

INA219.begin(0x40, 0.05)

Replace 0.05 with your actual shunt resistance in ohms.

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License

MIT