Joey Castillo Is Bringing Back the Vintage Segment LCD with a Smart New FeatherWing Board
Driven not wholly by nostalgia, this custom segment LCD add-on offers numbers, icons, and a low power draw great for battery projects.
Joey Castillo is back with another Oddly Specific Object, and this time it's a FeatherWing for compatible microcontroller boards, which packs the sort of classic LCD panel you would expect to see in a travel alarm clock — but custom-designed to Castillo's exacting standards.
"The LCD FeatherWing is a low-power, CircuitPython-compatible, I2C-driven display that works with Adafruit's Feather line of development boards," Castillo explains of his latest design. "It uses the BU9796 segment LCD controller to drive a custom liquid crystal display glass with 48 segments."
Those custom-designed display segments include five seven-segment numerical digits, with decimal separators for each plus a colon between the first two digits and the remainder and a negative sign at the left-hand side, bell, Wi-Fi, moon, paired arrows, and battery icon indicators, and AM/PM indicators for time.
"Segment LCDs are a kind of an old school technology that doesn't get a lot of love in maker projects," Castillo explains of the inspiration behind the board. "They have a striking, high-contrast look with great daylight readability, and they are staggeringly low power as display tech goes. But they are somewhat difficult to drive, requiring AC signals on all pins and multiple bias voltages.
"I made this LCD FeatherWing to simplify the use of LCD technology in Feather-oriented projects, so that makers could take advantage of this low-power, always-on display technology in their projects using the I2C protocol and an easy-to-use CircuitPython library."
It's not all about nostalgia, however: Castillo points out that segment-based LCDs draw considerable less power than LED-based displays — microamps, down from milliamps — allowing for projects that can display data for months on a single battery charge. "This makes it an ideal match for boards like the ESP32 Feather and the Feather M4," Castillo explains, "that support deep sleep."
Board kits are now available on the Oddly Specific Objects Tindie store at $15.95 each, Feather not supplied; Castillo has also published hardware design files to GitHub under the Creative Commons Attribution Share-alike 4.0 license, while the CircuitPython driver is made available under the permissive MIT license.