Main features

• Light compact 3d print design with magnets.
• Use a single CR2032 coin cell that will last longer than a year.
• Put image files on SD card (SD card needs to reformatted).
• Setup files to set update frequency and more.
• Easy to reprogram using a launchpad.
• Code is writing in Energia, a modified version of the Arduino IDE

Current software features

• Load Setup on startup.
• Intervals are set in 2 minute interval. For ones a day update use 720.
• Low Battery voltage detection.

Hardware

• Display: 2.7 inch b/r/w epaper display. More detail  here .
• MCU: Texas Instruments MSP430G2553IPW20R  (TSSOP-20)
• 32.768 kHz crystal for accurate time keeping.
• Mirco SD card socket.
• 3.3v boosting using AAT1217-3.3. SD cards not happy with less voltages.
• The necessary components plus 24 Position FFC, FPC Connector for the epaper display.
• Extra reset switch and mode switch.
• Header to flash the MSP430 and serial (UART) for debugging.

Power usage

• Standby current average 4.3 uA . When keeping time.
• Update power consummation  aground 100 uAh . When refresh screen with new picture.
• Battery will easily  last over a year if update once a day.
• Because of  the SD card power spikes, need a good quality make and will not drain to empty before read failures.