24 lines
1.2 KiB
Markdown
24 lines
1.2 KiB
Markdown
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Arduino valve
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=============
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This is an example how to open/close a Gardena Water-Valve (the ones
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that use a +9V block battery for power).
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Note that we used the L293D Dual H-Bridge circuit which needs +5V for
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power supply (while the Merkur-Board uses 3.3V) but it can use 3.3V
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inputs directly from the Merkur-Board without a level shifter. So it's
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probably a good idea to use some other H-Bridge circuit that can also
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use 3.3V. An advantage of the L293D might be that it can be used for two
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valves simultaneously (with the second, currently unused H-Bridge).
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We provide the schematics of our breadboard-design in
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valve-breadboard.png -- as noted above it's a good idea to use a
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different H-Bridge circuit.
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Also note that one of the pins we use in the software for signals to the
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H-Bridge (D4) is also used for the LED on the Merkurboard. The LED is
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*on* when the H-Bridge is *off*. This was nice for testing the
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breadboard circuit but should be changed for a real deployment to save
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power of the battery. It is also probably a good idea to turn off the
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power-supply of the H-Bridge with an additional MOSFET depending on the
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power consumption of the H-Bridge you're going to use.
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