INA219 is a microchip from Texas Instruments that can measure current and voltage bidirectionally and calculate power (Watts).
Overview
A variety of breakout boards are available, featuring either solder pins or pluggable Grove connectors (JST SH 1.0, QWIIC).
Most boards use an R100 (0.1 Ohm) shunt resistor, allowing a current range of up to ±3.2 A (bidirectional), and typically cost well under €2.00 per unit.
Tip:
The relatively large current range is due to the built-in PGA (programmable gain amplifier), which can amplify the shunt voltage drop by 2x, 4x, or 8x—at the expense of accuracy. Newer chips such as the INA226 and INA3221 no longer include a PGA, and therefore support lower maximum currents with the same R100 shunt resistor.
| Spec | Description |
|---|---|
| Supply Voltage | 3.3–5V |
| Load Voltage | 0–26V |
| Interface | I2C, 16 assignable addresses, default 0x40/64 |
| Max Current | 3.2A @ R100 (0.1 Ohm) shunt resistor |
Shunt Value and Maximum Current
The INA219 does not measure current directly; it measures the voltage drop across a shunt resistor. The shunt’s resistance determines the maximum measurable current.
However, the INA219 features a PGA (programmable gain amplifier) that can increase the current range by factors of 2, 4, or 8, allowing the chip to adapt to different current ranges with optimal precision.
Tip:
Newer chips like the INA226 and INA3221 do not include a PGA, so their current range depends entirely on the shunt resistor. For example, an INA226 with a typical R100 (0.1 Ohm) resistor can measure up to 820 mA, and the INA3221 up to 1.64 A. Thanks to its PGA, the INA219 can measure up to 3.2 A with the same resistor—assuming the PCB traces can handle the current.
Integrated Shunts
Most breakout boards come with a presoldered R100 (0.1 Ohm) shunt resistor, enabling measurement of up to 3.2 A (with the PGA set to 8x). In practice, the maximum usable current also depends on the PCB and trace thickness.
Always test each breakout board individually to determine its true maximum current capability.
Breakout Boards
Generic INA219 breakout boards typically have 6 pins and cost between €0.50 and €1.00:
| Pin Label | Description |
|---|---|
| Vin+ | Positive voltage for load circuit |
| Vin- | Negative voltage for load circuit |
| SDA | I2C data (SDA) |
| SCL | I2C clock (SCL) |
| GND | Common ground |
| VCC | 3.3V/5V supply for INA219 |
- VCC and GND supply power to the board (supports 3.3V and 5V).
- VIN+ and VIN- carry the load current. These may be duplicated and use thicker traces to support higher currents.
- SDA and SCL are the I2C communication lines for interfacing with a microcontroller.
GY-219 Boards
If you plan to measure high currents (2.0–3.4A), look for boards labeled GY-219.
The purple no-name boards, often marked GY-219, use larger PCB traces and a bigger shunt resistor compared to other generic boards.
These boards are less common and more expensive (€2.00–€5.00).
Grove Connectors
Some boards feature presoldered Grove/QWIIC/JST SH1.0 connectors, making it easy to chain multiple I2C sensors.
On these boards, VCC, GND, SDA, and SCL are exposed three times: as solder pads and via two Grove connectors, allowing straightforward daisy-chaining of I2C devices.
Tip:
You can connect the board to your microcontroller using the solder pads, turning it into an I2C hub with two additional connectors for more I2C device chains.
The load connects high-side via two solder pads to the shunt resistor. The traces are usually thick, but the solder pads may not be labeled, making it unclear which is Vin+ and which is Vin-:
If readings are negative, simply swap the pads.
Quality Boards
Affordable no-name boards are often clones of designs from reputable vendors (such as Adafruit). On quality boards, load pins are clearly labeled:
The Adafruit board, for example, uses a larger shunt resistor, which is beneficial for measuring higher currents due to improved heat dissipation.
Quality comes at a price: Adafruit boards cost around €10.00, while generic versions can be found for €0.50 on AliExpress.
I2C Address
The INA219 communicates digitally via I2C, so a microcontroller is required.
I2C is address-based: each device needs a unique address. The INA219 supports up to 16 different I2C addresses, but most breakout board documentation states that only four are easily configurable.
The default I2C address is 0x40. To use multiple INA219s, you can change the address via two solder bridges, typically labeled A0 and A1:
| A0 | A1 | Address (hex) | Address (decimal) |
|---|---|---|---|
| - | - | 0x40 |
64 |
| closed | - | 0x41 |
65 |
| - | closed | 0x44 |
68 |
| closed | closed | 0x45 |
69 |
Using 16 I2C Addresses
If you need more than four INA219 boards, you can configure up to 16 different I2C addresses.
This is possible because the A0 and A1 pins on the INA219 chip can be connected to GND, VCC, SDA, or SCL, resulting in 16 possible configurations.
The solder bridges provide a simple way to connect these pins to VCC, allowing easy selection of 4 out of the 16 addresses.
How it works:
- Leaving a solder bridge open connects the pin to
GND(pulled low). - Closing the solder bridge connects the pin to
VCC.
Identifying True A0 and A1
To configure the remaining 12 addresses, you need to connect A0 and/or A1 to different pins. First, identify which side of the solder bridge is the actual chip pin.
Usually, the inner pad of the solder bridge is the true chip pin, while the outer pad is always connected to VCC. You can verify this with a multimeter:
- Measure resistance between the outer pads of both solder bridges—they should be close to 0 Ohms (connected).
- Measure resistance between the outer pad and the VCC pin—they should also be close to 0 Ohms.
If not, check the other pads. The pads not connected to VCC are the true I2C configuration pins (A0 and A1).
Using All 16 I2C Addresses
To access all 16 addresses, connect the true side of the A0 and/or A1 solder bridge to one of the following:
| A0 | A1 | I2C Address | Accessible via Solder Bridge |
|---|---|---|---|
| - | - | 0x40 |
yes |
| - | VCC | 0x41 |
yes |
| - | SDA | 0x42 |
no |
| - | SCL | 0x43 |
no |
| VCC | - | 0x44 |
yes |
| VCC | VCC | 0x45 |
yes |
| VCC | SDA | 0x46 |
no |
| VCC | SCL | 0x47 |
no |
| SDA | - | 0x48 |
no |
| SDA | VCC | 0x49 |
no |
| SDA | SDA | 0x4A |
no |
| SDA | SCL | 0x4B |
no |
| SCL | - | 0x4C |
no |
| SCL | VCC | 0x4D |
no |
| SCL | SDA | 0x4E |
no |
| SCL | SCL | 0x4F |
no |
IMPORTANT: Never wire the wrong side of the solder bridge. Always ensure you have correctly identified the true pin side. The opposite side is always connected to VCC.
If you connect the wrong pad (the one connected to VCC) to:
GND: you will short-circuit the power supply.SCLorSDA: you risk damaging the INA219 and/or your microcontroller, as this will short the I2C line during communication (normally, a current-limiting pull-up resistor keeps I2C lines high, but now the line is directly connected toVCC).
How to Connect a Load
The INA219 requires two power supplies: one for itself, and another for the load under test.
| Pin | Purpose | Connected to |
|---|---|---|
| VCC | Powering INA219 | +3.3–5V |
| GND | Common ground for INA219/load | Ground |
| Vin+ | Powering load | +0–26V |
IMPORTANT: Both power supplies must share the same ground. Otherwise, readings will be unstable and inaccurate.
High-Side Load Connection
The load under test must always be connected on the high side (INA219 in series with the load’s positive pole):
| Pin | Connected to |
|---|---|
| Vin- | Positive pole of load |
| GND | Negative pole of load |
Important:
Connect Vin-, not Vin+, to the positive pole of the load. Vin+ connects to the positive pole of the load’s power supply. If you swap Vin+ and Vin-, current and voltage readings will be negative.
Programming
The INA219 communicates digitally via I2C, so a microcontroller is required. Most microcontrollers support I2C.
Arduino IDE / PlatformIO
There are many excellent tutorials, videos, and ready-to-use libraries available.
ESPHome
[ESPHome] natively supports the INA219 via its ina219 sensor platform, with many sample configurations available.
Materials
Slow Website?
This website is very fast, and pages should appear instantly. If this site is slow for you, then your routing may be messed up, and this issue does not only affect done.land, but potentially a few other websites and downloads as well. Here are simple steps to speed up your Internet experience and fix issues with slow websites and downloads..
Comments
Please do leave comments below. I am using utteran.ce, an open-source and ad-free light-weight commenting system.
Here is how your comments are stored
Whenever you leave a comment, a new github issue is created on your behalf.
-
All comments become trackable issues in the Github Issues section, and I (and you) can follow up on them.
-
There is no third-party provider, no disrupting ads, and everything remains transparent inside github.
Github Users Yes, Spammers No
To keep spammers out and comments attributable, all you do is log in using your (free) github account and grant utteranc.es the permission to submit issues on your behalf.
If you don’t have a github account yet, go get yourself one - it’s free and simple.
If for any reason you do not feel comfortable with letting the commenting system submit issues for you, then visit Github Issues directly, i.e. by clicking the red button Submit Issue at the bottom of each page, and submit your issue manually. You control everything.
Discussions
For chit-chat and quick questions, feel free to visit and participate in Discussions. They work much like classic forums or bulletin boards. Just keep in mind: your valued input isn’t equally well trackable there.
(content created May 20, 2025)