INA237 Qwiic Current Sensor

Jargon buster

Plain-language definitions for the technical terms used above.

ADC

An analogue-to-digital converter reads a changing voltage and turns it into a number the microcontroller can use. It matters when connecting analogue sensors such as light, sound, or variable-resistor sensors.

breakout

A breakout board carries a small or fine-pitched component and brings its connections out to standard, breadboard- and header-friendly pins. Describing a part as a breakout means it can be wired into a project without soldering directly to the component's tiny contacts.

DC

DC means direct current, where electricity flows in one constant direction, as supplied by batteries, USB ports and many plug-pack power supplies. When a product specifies DC, it runs from a DC supply rather than mains AC, so you need to provide the correct voltage and polarity.

Gain error

Gain error is a scaling error in which a device's output grows slightly too much or too little across its range, affecting converters, amplifiers and sensors alike. It matters wherever the exact relationship between the input value and the resulting output needs to be accurate.

GND

GND is the ground or reference connection (0 V) for a circuit. When connecting two devices together, their grounds must be joined so both agree on what counts as a low or high signal.

I2C

I2C is a two-wire communication bus used by many sensors and small modules. It matters because several I2C devices can share the same two wires, but each device needs a compatible address and your controller must support I2C.

INA237

A Texas Instruments digital power-monitor chip used to measure quantities such as current, bus voltage, power and temperature. When a product mentions INA237, check the supported voltage and current ranges and how it connects to the rest of the circuit.

LED

A light-emitting diode (LED) is a small electronic component that emits light when current flows through it in the correct direction. Because it only conducts one way, its polarity matters, and a through-hole LED must be soldered the correct way around to light up.

microcontroller

A microcontroller is a small computer on a single chip that runs a stored program and controls connected inputs and outputs such as buttons, sensors, displays and communication interfaces. In a device built around one, it is the part that executes the code and coordinates the device's behaviour.

open-drain

A digital output style that can pull a signal line low but cannot drive it high by itself, so it needs a pull-up resistor or another circuit to make the high level. Open-drain outputs are often used for shared alert lines or buses because multiple devices can safely pull the same line low.

ppm

ppm means parts per million, a common way to express very small gas concentrations in air. For CO₂ sensors, the ppm range tells you what levels the sensor can measure, such as normal indoor air through to poorly ventilated spaces.

Qwiic

Qwiic is a plug-in connector system for I2C devices that uses small 4-pin cables, so you can connect compatible sensors without soldering. It matters because your controller or adapter also needs Qwiic, or you will need a cable or breakout to wire it up.

SCL

The clock line used by the I2C bus to keep data transfers timed between a controller and connected devices. When wiring I2C, SCL must be connected to the SCL pin on every device sharing the bus.

screw terminal

A connector that clamps bare wire using a small screw, making it easier to attach and remove wires without soldering. Screw terminals are useful for power wiring or thicker wires that are not suited to small plug-in connectors.

SDA

The data line used by the I2C bus to carry information between a controller and connected devices. When wiring I2C, SDA must be connected to the SDA pin on every device sharing the bus.

SDA/SCL

SDA and SCL are the two signal lines used by an I2C bus: data and clock. Seeing these names helps you identify the correct connections when wiring I2C devices, even though Qwiic cables usually hide that wiring for you.

shunt resistor

A very low-value resistor placed in the current path so the board can measure the tiny voltage drop across it and calculate current. Its resistance and tolerance affect the maximum current range, heat produced and accuracy of the readings.

through-hole

A mounting style where the component leads pass through holes in a circuit board and are soldered on the other side. Through-hole parts are often easier to handle and solder by hand, which is useful for classroom and hobby projects.

VBUS

VBUS is a label for a bus or supply voltage. Most commonly it is the +5V power line carried over USB, though on power-monitoring hardware it instead marks the bus-voltage input being measured, so check which sense applies before connecting power or a measurement point.

VCC

VCC is the positive power-supply connection on a chip or module. Connecting it to the correct supply voltage is needed for the part to power on and helps avoid damaging the electronics.