ZEReader

A Gentle Power Off for ZEReader: Replacing the Hard Switch with a Latching Power Circuit

• Anna-Lena Marx
• November 16, 2025
• Zereader , Electronics , Embedded

With the second revision, the way ZEReader is turned on and off got a massive redesign.
The hard on/off switch in the first revision was dead simple and worked great—with one big flaw from a user’s perspective. You could not recognize if the reader was on or off on the first sight. The old switch just closed or opened the loop with the power supply, and due to the E-Paper display just holding the state, you had no chance to tell.
Besides, there was no possibility at all to implement some kind of graceful shutdown mechanism, which would allow me to save all important state information and show a clear device off indicator.
This situation was totally fine for the very first prototype, but it started to get annoying very soon. A new approach was needed!