Giovanni Carrera's INA226-Based Ammeter Provides Arduino-Compatible Power Monitoring
Using the digital output of the TI INA226 and a modified version of Jarzebski's Arduino library, the build achieves great accuracy.
Giovanni Carrera's latest build for the ArduPicLab blog aims at demonstrating how the TI INA226 part can be used to create an Arduino-compatible power monitoring ammeter — the ArduINA226.
"In the past I have developed various projects of ammeters based on Hall effect current sensors such as the ACS712, or on High-Side Current-Sense Amplifiers such as the MAX4080SASA or made with operational amplifiers. All these systems have an analog output which must then be digitised," Carrera explains. "The INA226 sensor has a digital output and incorporates a 16-bit ADC for which a high accuracy and precision is obtained."
"It measures current and voltage and calculates power while Arduino communicates with the chip, presents the measurements on an LCD display and stores them on a micro SD card. This chip operates with a maximum voltage of 36 volts while the current is limited only by the shunt used."
The INA226 is already a popular device in the Arduino world, with a series of libraries available for integrating it into your programs. "I used the Korneliusz Jarzebski library," Carrera notes, "which seems to me quite complete even if I had to make some changes to two functions."
In addition to the INA226, on a commercial break-out, Carrera's design incorporates a two-line 16-character LCD display and controller, a microSD module for data storage, and a modified shunt, all controlled via an Arduino Nano. "You can use other Arduino boards, such as Arduino Uno or Arduino Pro," Carrera advises, "but this board is very compact, complete with USB adapter, and can be mounted on a prototype pre-drilled PCB.
"With a ten measuring points, compared with a precision multimeter, the results have been very good," Carerra writes. "In my case, the VBUS voltage was very accurate and required no correction. The current is slightly lower than the expected value (correction of 1.0092) and the linearity was excellent with R = 0.999995."
A full schematic, an Arduino sketch, and the modifications required to Jarzebski's Arduino library can be found on the ArduPicLab website.