Eink-word-clock-watch

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Project E-ink wordclock watch
E-ink wordclock watch
Status In progress
Contact jelly
Last Update 2019-04-15

Plan

The plan is to make an e-ink watch with a 1.54" display which will display a word clock of the current time which updates every ~ 3/5 minutes.

Requirements

  • Refresh e-ink screen (ie. update word clock) every ~ 3 minutes
  • Be able to set the time or sync it via WiFi/Radio?
  • Capable of running for > one month

Interfaces

  • SPI
  • Serial for debugging / flashing?
  • RTC

Parts

  • e-eink screen datasheet datasheet Requiring 3.3 V, SPI and has refresh power req. of 26.4 mW with standby power of < 0.0 17 mW (0.0264/3.3 = 8mA)
  • Coin cell (3V ~ 225 mAh / lithium battery small enough? (if powerful enough) 3.7 V 180 mAh 502025 Lithium Polymeer Li-Po should fit under the display, but might be too big.

MCU

  • atmega 328P 320 uA "active mode", 200 nA power down and 1.3 uA power save.
  • stm8s
  • esp32 pico 150-10 uA

Hardware

  • Display size (e-ink) 31.8mm × 37.32mm × 1.05mm
  • PCB
  • 3d printed case
  • arm strap?
  • I2C RTC chip

Prototyping

Use a e-ink breakout board with the preferred $MCU to display a simple "hello world" text every three minutes and measure the power usage.

Studying material