Previously, I described the shutting down of the Raspberry Pi2 with an Arduino here. The next logical step was to add a digital combination pass-code to add parental controls so my kids could not turn on the system without my authorization. I wrote some quick firmware which is currently too embarrassing to post which implement the following features:
Digital combination pass-code to turn on system
Countdown timer in increments of 10 minutes
Unlimited time mode for special occasions
Neo Pixel ring to show current timer status
I used the following NeoPixel ring from Adafruit found here
I also designed and printed a holder for the NeoPixel ring to mount it on the front acrylic panel.
I purposely coded in a security vulnerability into to combination lock to encourage my kids to begin thinking about security systems. Currently, you are “kicked out” and have to re-enter the combo as soon as you select one wrong digit. So any adult mind would quickly try each digit for each position and come up with the combo. If they figure it out, they will be rewarded with the elusive “unlimited mode” for a while before I remove the bug.