OpenSprinkler › Forums › Hardware Questions › OpenSprinkler Pi (OSPi) › How to read current station status? › Re: Re: How to read current station status?
July 15, 2013 at 1:53 pm #24830
By the way. You mentioned that you are struggling to understand shift registers. This article offers a good explanation: http://bildr.org/2011/02/74hc595/. This will also explain why the the complete state of the controller has to been reset each time a station is opened or closed. The shift register is cleared out and 8 new bits are sent to the register (or more if you are using an expander board; the linked article also explains how shift registers are daisy chained, which is exactly how the expansion boards work — I think).