The Final Countdown - An RP3250 based Event Timer
Sometimes, we are counting down the days to an important event, such as a trip or an anniversary. A few years ago, I built a timer for this, using an ESP-8266 board and two LED bar displays: It worked fine, but powering it through the USB connector was a bit of a pain. So, I started thinking about a battery-powered device. Looking at my parts stash, I found a few components that could be used in this project: An e-paper display: it shows the last image even if powered down. A tinyRTC module, with a DS1307 with battery backup and an AT24C32 EEProm: it can save the event date and keep track of the current date and time. A XIAO RP2350 board: it has support for a rechargeable battery. I had enough experience with the first two modules, the XIAO RP2350 brought the adventure of learning about power saving with the RP2350.