Controlling 32 solenoid valves from a single BeagleBone Black

Question

I am trying to control 32 solenoid valves from a single BeagleBone Black. My EE skills are not up to par for this task, but I am learning.

In this system, at most one solenoid will be active at any given time, which simplifies things. Working from intuition, my thought was to control a single solid-state relay via one of the BBB's GPIO pins and then demux the SSR's load circuit output to the 1-of-32 solenoid that is selected using 5 (log₂32) additional GPIO pins on the BBB.

The solenoids being controlled are Spartan Scientific 4B23. They are 24VDC with a 10W power rating.

My first idea was to use a SparkFun A/D mux breakout board (datasheet). I don't think this will work, however, since the required solenoid voltage and current both exceed the absolute maximum rating of the IC.

Without just simply introducing 32 SSRs (one to control each solenoid valve), is there an economical way to do this? Is there a mux board that can handle this kind of voltage and current?

Answer 1

There are many ways to control higher-powered/higher-voltage devices with MCU GPIO pins. Your suggestion to use SSRs could work but these are somewhat expensive and not really needed here.

The most common way of driving loads such as your solenoids is via a simple circuit such as this:

^{simulate this circuit – Schematic created using CircuitLab}

Pick appropriate values of the R and NPN transistor so that you can optimally drive the relay coil.

Answer 2

There are a few relay drivers with 8+ outputs (none for 32, you'll have to cascade) that take SPI and can handle that kind of current. Just include "relay driver" or "power driver" in your search and you'll find them.