Solid state electronic irrigation controller

Claim 1

A solid state electronic control system including: a plurality of electrically controlled valves; a micro-controller including a memory; switching circuitry for causing said valves to be selectively energized; control circuitry connecting said micro-controller to said switching circuitry selectively to operate said switching circuitry under the control of said micro-controller; a keyboard connected to said micro-controller for introducing selected programs into the memory of said micro-controller concerning the timing and duration of the energizing of said valves; circuit means connected to said micro-controller and including a display for displaying words and numbers to facilitate the programming of the micro-controller, to monitor the operation of the micro-controller and to exhibit malfunctions in the system; a direct current power supply connected to the micro-controller; means for connecting said direct current power supply to an alternating current source; means for connecting said micro-controller to said alternating current source to enable said micro-controller to control said switching circuitry during normal operation of said control system and to enable said micro-controller to cause said switching circuitry to de-energize all of said valves in the event of failure of said alternating current source; a back-up battery connected to the power supply for providing an energizing voltage to the micro-controller in the event of failure of the alternating current source so as to maintain the programmed data to the memory of the micro-controller to enable the system to continue to perform all of its function except actual control of said valves; and internal circuitry in said micro-controller and a resonant circuit connected to said micro-controller responding to power from said direct current voltage power supply and from said back-up battery for generating an alternating current signal of a selected frequency and providing a simulated alternating current source for the micro-controller when the system is operating on battery back-up so as to maintain clock signals in the system.