{"id":412936,"date":"2026-05-05T13:51:08","date_gmt":"2026-05-05T13:51:08","guid":{"rendered":"https:\/\/www.newsbeep.com\/nz\/412936\/"},"modified":"2026-05-05T13:51:08","modified_gmt":"2026-05-05T13:51:08","slug":"lightink-a-solar-powered-esp32-smartwatch","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/nz\/412936\/","title":{"rendered":"LightInk, A Solar Powered ESP32 Smartwatch"},"content":{"rendered":"

There\u2019s something about the ESP32 family of microcontrollers and timekeeping. We probably see it in clocks as often as we do anything else; we also probably see more clocks with one as the beating heart than any of the many other possible timekeeping options.<\/p>\n

[Daniel Ansorregui]\u2019s LightInk watch<\/a> is no different in that regard \u2014 but it is very different in one important detail, because like any other smartwatch, you won\u2019t have to worry about battery life. Outside of gloomiest Gotham, its built-in solar panel should be able to keep it charged.<\/p>\n

That\u2019s for a few reasons. The obvious one is the e-ink display, which only takes a sip of power during updates. That\u2019s hardly unique to [Daniel]\u2019s projec t\u2013 he quite explicitly calls out the Watchy project, which we featured previously<\/a>, as where he got the idea of putting e-ink and an ESP32-PICO together on his wrist. What is unique is the delightful hack [Daniel] is using to minimize power usage, which is our favorite part.<\/p>\n

Obviously while the display isn\u2019t updating and there\u2019s no input from the touchscreen, the microcontroller should be in deep sleep. So, [Daniel] sets wake-up timers and an interrupt for the touch input and it\u2019s all good, right? Well, yes, but when the ESP32 ran through a normal startup, [Daniel] clocked 28 mS to boot \u2014 and a whole milli-amp-second of juice out of the battery. That was pretty much down to the need to write the code from flash into RAM, and good luck power-optimizing that. Instead [Daniel] found a way to skip it, using the RTC.<\/p>\n

The RTC has its own memory, which the ESP32 can start from in a microsecond or so. It turned out large enough to squeeze everything needed for these fast updates, including the SPI display driver. Since around two thirds of the watch\u2019s power consumption was just booting up, slicing that doubled the energy efficiency, making solar power possible. Well, as long as you don\u2019t get too excited using the fancier \u201csmart\u201d features like GPS and LoRA too often. Relatively speaking, those are power hogs. There are actually a lot of features, but we\u2019ll let you check them out in the demo video below if you\u2019re really interested.<\/p>\n","protected":false},"excerpt":{"rendered":"There\u2019s something about the ESP32 family of microcontrollers and timekeeping. We probably see it in clocks as often…\n","protected":false},"author":2,"featured_media":412937,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[17],"tags":[356,111,139,69,145],"class_list":["post-412936","post","type-post","status-publish","format-standard","has-post-thumbnail","category-gadgets","tag-gadgets","tag-new-zealand","tag-newzealand","tag-nz","tag-technology"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/412936","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/comments?post=412936"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/412936\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media\/412937"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media?parent=412936"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/categories?post=412936"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/tags?post=412936"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}