Random flashing LEDs when using shift registers and turning on the system: how to fix? Answered
I have a setup using 5 shift registers (74HC595s) hooked up to an arduino micro. Everything works great! So much so, that I didn't pay too much attention to the start up issue.
When I start up the system (either by hooking up a battery or plugging it into a USB socket) the LED's hooked up to the 595's will either turn on according to the last pattern they had, or turn on randomly. I was following the Arduino tutorial for this, and it does state that "The one flaw of this set up is that you end up with the lights turning on to their last state or something arbitrary every time you first power up the circuit before the program starts to run." It also states "You can get around this by controlling the MR and OE pins from your Arduino board too, but this way will work and leave you with more open pins." However, I'm either missing it or it is not outlined how to hook up the MR and OE pins to the setup to correct this.
Any help is greatly appreciated!