Volos Projects' LILYGO T-Display S3 Power Meter Mimics a Classic Multimeter with Some Neat Extras
Designed to mimic a traditional LCD display panel, and with digital and analog readouts, this multi-functional tool is cleverly coded.
Pseudonymous YouTuber Volos Projects has built a surprisingly full-featured multimeter from a LILYGO T-Display S3 and a Texas Instruments INA219 — plus a few additional sensors thrown in for good measure.
"This is a power meter project," Volos explains of his latest creation, "but I also added time, temperature, and a few more surprises to it. [The LILYGO T-Display development boards] have one tiny [Grove-compatible] connector which is used to connect different I2C modules. [The] Soldered company produce many difference modules and sensors that use the same connector."
It's these modules, connected using flying wires with no need to solder anything down, which form the inputs of the do-it-yourself multimeter. As with an off-the-shelf model, the device's primary function is to measure the voltage and current draw of a connected circuit — leaning on a TI INA219 for the measurement job. The readings are shown on the T-Display's integrated 1.9" LCD screen, using a hybrid analog-and-digital visualization with large seven-segment-style digits atop a sliding scale.
While measuring voltage and current is enough to lay claim to "multi" meter functionality, Volos has taken the project a few steps further. A Bosch BMP180 module provides ambient temperature, humidity, and air pressure readings, while a real-time clock (RTC) module puts the current time on-screen. There's also a linear potentiometer, showcasing the ability to measure resistance — and also providing a control for display brightness for good measure.
The project's code is written in the Arduino IDE and compiled for the T-Display S3's Espressif ESP32-S3R8 microcontroller, using a custom user interface which simulates a classic monochrome LCD. "I really love this design," Volos says. "It looks like a multimeter display, and I spent hours and hours to program this."
More information is available in Volos' video on the project, while the source code can be found on GitHub under an unspecified open source license.