Hello!
I have made a mini bell system for home. I though I would come through cheaper if I make Arduino clones myself which share the same clock. One Arduino sends clock to the next. 5 of them are wired like this and it worked pretty well. Recently I changed the power supply from 5 cheap wall warts (one for arduinos, rest for motors) to one old PC power supply. The Arduinos were and are always supplied through 5V regulator (from 12V).
For easier changing of variables I added pc communication and variables are stored in eeprom.
After I changed to PC power supply, every once in a while one of them will start behaving strangely. Week ago one of them went crazy and started pulling the motor in only one direction never stopping (it should have been swinging). In past few days it always so happens that another of them stops responding to signals randomly during the day (usually only once). When I connected PC to it and asked for variables (to see if its still running) it sent me corrupted variables:
normal:
corrupted:
(explanation: power duty cycle and power iterations give the motor more power for the first few swings)
Now, I know the pc connection is working as I have used it many times in the past to set variables and if it wasnt there would be wrong variables stored on the Arduino in the first place. I also use CRC to check sent data.
When I reset the Arduino everything returns to normal. Variables are loaded from EEPROM so it must also be working properly.
Something happens during "waiting" time which corrupts the arduino is my guess. A few hours ago a hammer unexpectedly striked, and as I am using pull-up resistors it could be a sign that voltage has dropped for a fraction of a second, triggering the signal, and has also a chance of corrupting arduino memory (?) (note that I AM using decoupling caps on each of them).
I should also state that I am not using dummy load on power supply.
Did anyone have any similar problems and could help me with this? Much appreciated!
Here are some pictures of the setup:
entire setup
regulator and oscillator
control board
one unit
pc communication