Imported from GitHub: antscher/Project_calendar_rooms · commit 5c8e9f7 · license GPL-3.0

Description

This repository is a complete guide to make calendars screen that show calendars in a local building

README

Hardware Components Selection

ESP32-S2 Microcontroller : ESP32-S2 pico from waveshare

Here the link : https://www.waveshare.com/esp32-s2.htm

• Why this choice?

  • Built-in WiFi capabilities for network connectivity
  • Low power consumption with deep sleep modes
  • Sufficient GPIO pins for e-ink display interface
  • Cost-effective solution for IoT applications
  • Native USB support for easy programming
  • Enough RAM for rendering the image before displaying it

  Can be power supply between 10V and 1.8V theorically in reality it is needed to be superior to 2.65V

Waveshare E-Ink Display : Spectra 7.3" from Waveshare

Here the link : https://www.waveshare.com/7.3inch-e-paper-hat-e.htm

• Why this choice?
  • Ultra-low power consumption - only uses power when refreshing
  • Excellent readability in various lighting conditions
  • Maintains display without power
  • Available SPI interface for easy integration with ESP32
  • 6 colors

Battery Selection : Roomz display battery

Here the link : https://www.bechtle.com/fr-en/shop/roomz-display-spare-batteries--4329865--p

• Why not rechargeable Li-primary

  • High energy density
  • Low self-discharge rate
  • Long cycle life
  • Safe for fire problems

  Normally the battery will stay really close to 3V during all it live cycle but a varation can cause effects. Capacity (%) Voltage (V) 100% 3.0 – 3.2 V 90% 3.0 – 3.1 V 80% 2.95 – 3.1 V 50% 2.9 – 3.0 V 20% 2.8 – 2.9 V 10% 2.7 – 2.8 V 0% ~2.0 – 2.5 V

  Note : After testing with different input voltage, the results are :

  • 2.65V : work normally

  • between 2.65 and 2.4 : work but risk of losing is SPRAM
  • < 2.4 V : not working at all

  Conclusion : we can use even if we consider there is risk of malfounctionning at the end of life (Possibility utilising NVS memory but there is a limit in R/W cycle)

Power Considerations

• E-ink display only draws power during updates
• ESP32-S2 deep sleep mode < 10µA
• Expected battery life: 2-3 years between replacing battery

The PCB

The pcb is made on Kicad You can open it and modify it with Kicad, may be you will need to downloads some library for footprints You can purshase it, but you have to first expot in gerber file. All of the componnent required are in the "Component list.xlsx", you can change some component by similar ones but make sure the footprint is compatible (or modify it).

The support of the frame

It is made in Fusion 360, you have access to the STL file to print the design. Use M3 screws to attach it.

The frame

The frame is made with Inkscape, it is a .svg file. It is designed for 3mm wood. It needs to be cut (red lines) and engraved (blue surface). You need to glue it except the back, which just fits in so you can remove it after. For the screen, tape it or glue it.

Frame Images

See the following images for reference:

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