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A project log for Darkrook timer and safelight

An integrated safelight/timer console, which will have a countdown timer with three preset timer options, and enlarger switch

marcellothearcanemarcellothearcane 08/24/2020 at 12:000 Comments

I had to order some cheap red LED strips from Amazon, and it's surprisingly hard to find plain and simple 5v ones.  These arrived, and I added 2N3904 NPN transistor to drive them.

Coding it was fairly easy actually.  I used the blinkWithNoDelays() sketch as a starting point, and just ran through checking inputs and timers based on millis().

A quirk is that you can't press down multiple timer buttons, or the timer start button, or enlarger button reliably because they are all in a voltage divider together. However, there's no need to press these buttons together, so that's not a problem.

One feature is that it saves the timers in the EEPROM, which means that they persist when the timer is switched off.  Another feature is that I convert seconds to MM:SS time, which is more readable for minutes.  There isn't a colon on my display to mark this, but I can live with that.

The whole code is in this gist: