My Newest Wacky Idea...

[Hwk-I-St8]

If you've seen my other threads, you know that I'm down the rabbit hole of trying to get PID controlled induction rig working. The Auber Cube was a bust. Now I'm looking at craftbeerpi.

I was originally thinking I'd control everything from a craftbeerpi-based rig. I'd need to get relays for the 240v heater output, plus relays for any switches, such as a pump. I would need to build a box, add all the sockets, plugs, relays, etc. Doing the math, I quickly realized I was really just building another complete controller with all the cost associated with it.

Then I thought, well, I could just pillage my cube for parts. Heck, I could even maintain the manual control of the pumps and I wouldn't need additional relays.

Then I thought, what if I just modified the cube to use a raspberry pi as the PID instead of the DSPR320. Naw...probably not enough room in the cube to add that.

So, what about this idea:

I buy a raspberry pi and display and install them in this case.

Then I run the necessary GPIO connections out of the pi and into my cube. This is the wiring diagram for my cube:

I'd disconnect the power, RTD and SSR driver lines to the DSPR and, instead, connect the RTD and SSR to the appropriate GPIO pins on the pi. That way the pi would be the PID but everything else would work in the cube box. Plus I wouldn't have to buy and build another box for all usual controller parts.

Is that crazy? My biggest concern would be whether the RTD sensor would work with the pi. If not, I could just run a different temp probe directly from the pi to the kettle.

Thoughts?

 

[Hwk-I-St8]

Upon further review, I think I'll just leave the dspr powered up, but disconnect the lines to the SSR. Then I can use the dspr as a secondary thermometer and run a separate thermo probe to the pi.

Any reason I couldn't use some sort of DPDT switch to switch the control lines to the SSR from the DSPR to the pi? That way I could still use the cube as originally designed without taking it apart and re-wiring it if desired.

 

[doug293cz]

A DPDT switch for the SSR trigger inputs will work fine. The easiest temp sensors to use with a RPi are the DS18B20 1-Wire digital temp probes.

Brew on

 

[golfindia]

Using RTDs with a Pi is a pain. DS18B20s are a buck a piece.

Id skip the display. It will just bog down the CPU and it defeats the purpose of building a networked controller.