> Put it on top. Connect the I/O lines on your little PC to the output of the smoke detector chip. Let it do the heavy lifting, the stuff that you aren't sure y

> Put it on top. Connect the I/O lines on your little PC to the output of the smoke detector chip. Let it do the heavy lifting, the stuff that you aren't sure you can do safely and which it has proven it can do for decades. I worked on a network communications part (the little PC) of a device that controls train signals (the smoke detector chip). This is exactly how it's architected -- the safety-critical components are isolated from the non-safety-critical ones. The busybox linux board does not go in between the sensors and the vital control logic, but rather "on top"