Joey Castillo's Latest Oddly Specific Object Is the Energy-Harvesting Solar Feather Express

Joey Castillo, of Oddly Specific Objects, has completed the design of a Feather-compatible development board built with solar energy harvesting projects firmly in mind: the low-power Microchip SAM L21-based Solar Feather Express.

"I'd resolved on not designing any new gadgets this year," Castillo wrote when unveiling the at-the-time unnamed Feather-format development board in August last year. "But I have a couple of solar-oriented things on the horizon, and after [Microchip] SAM L21 low-power tests proved just too promising, I couldn't help myself."

At the time, all that was available was a render of the board's design — but now it finally exists in the real world too. "Sometimes things take longer than you expect," Castillo says of the delay between initial design and working board. "The important thing is that you do them. Anyway: meet the Solar Feather Express. Despite everything I have going on — and I have plenty — I managed to build this today."

The Solar Feather Express is, as the name implies, a Feather-format development board built with solar energy harvesting in mind. It uses Microchip's SAM L21 system-on-chip, offering what the company calls "picoPower Technology" with support for full functionality at operating voltages down to 1.62V and a rapid wake time from deep sleep modes. That gives the board a single Arm Cortex-M0+ core running at up to 48MHz, 40kB of static RAM (SRAM), and up to 256kB of embedded flash storage.

For power, there's a high-efficiency Torex Semi XC6220 voltage regulator with SMA diodes to automatically switch between USB power and a solar input depending on which is higher — then feed the incoming power to a battery through a Texas Instruments BQ24074 management chip.

"I'm pledged to [do] two public art installations in the near future," Castillo explains of the reason for finally bringing the concept design into the real world, "and this board is going to drive them."

More information is available on Castillo's Mastodon post; at the time of writing, he had made no public commitment to a full-scale production run.