Auto Start

Auto Start for UPS3v2 UPS 


1. Introduction

   This project shows how to use an ATTiny microcontroller to restart a UPS3v2 after it has been automatically shutdown due to a lightning storm detection event.  The ATTiny is included as part of the Disconnector 1 board that separates a UPS from wallpower in the event of a lightning storm.

   We know that we cannot provide complete protection from a lightning strike.  Lightning will have its way with your home, appliances, and electronics.  It cannot be prevented.

   But, you can protect from damaging surges caused by nearby lightning.  You should have a whole house lightning/surge protection such as this one from SECO.  Also, you should install surge protective devices at each outlet where sensitive electronics may be installed. I like this one from Amazon.  This device from APC also works well.


2. Description

   Once you've implemented SPDs, you can use/build a lighting detection system to detect the presence of nearby lighting and potentially close-by lightning strikes to automatically shutdown and disconnect Raspberry Pi or other small computers.

   A lightning manager on this network monitors lightning data from the Acurite sensor and publishes probability data on a TCP socket.  The local computer can use that data to order a shutdown of the system.  For those computers supported by the UPS3v2, shutting down the client and UPS turns off the 5 volt supply to the Disconnector board.  The relay then turns off, which disconnects both leads of the input power from the UPS.

   But once the computer is shutdown and disconnected you have no way to automatically restart the system.  The UPS3v2 controller is designed so that once it is shutdown, an operator must physically press the Start button to get it going again.

   Enter the AutoStart board.  It has an ATTiny45 powered on by the relay which disconnects the wall power.  It is powered by two small AA cells and runs in sleep mode most of the time to minimize its power consumption. During the one hour delay period, it blinks a small 3mm LED every 8 seconds.  During the last minute prior to restart, it double-blinks the LED.  After the delay, the AutoStart board will electrically press the Start button.

   The UPS3v2 project was designed such that a lengthy power loss (such as a tripped GFCI) would cause the UPS controller to turn everything off to prevent damage to the NiMH batteries.  If wall power is still present after one hour (tested by the optocoupler), the AutoStart board will generate the start signal to the UPS. If no wall power is present, such as a GFCI trip, the UPS cannot be restarted.

3. Pictures

The prototype Autostart board:

The Disconnector 1 perf board with included Autostart circuit.

The relay and optocoupler are key to providing the needed isolation from voltage surges which may be present during a lightning storm.

The OSH Park rendering of the commercially produced printed circuit board:



Top view

Bottom view


A completed board from the OSH Park blank pcb



4. Schematic

AutoStart schematic


8. Operating Code:

   For the ATTiny controller:
AutoStart.ino



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