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