Working with sparkfun amp MAX31855K and Raspberry Pi Zero 2W
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Not so much an issue as much as information for those in a similar position.
I was curious to switch from https://github.com/brycesub/silvia-pi/ to this package, and my first attempt was with the silvia-pi hardware. This involves a different amp than the one suggested by this module.
I am also using a Pi Zero 2w. This is a multiprocessor unit, and I hope it overcomes the limitations Gregory points out in his readme.
https://www.sparkfun.com/products/13266
It is still running on the MAX31855K, so I was hopeful for a simple swapout.
At first, I was getting the error: "Failed to sample temperature {"error": "short to ground"}"
I changed two things at the same time and the issue was resolved.
- I switched the USB power source from my computer to the same wall outlet that was charging the Silvia
- I plugged the free-floating "NC" line running from the thermocouple into a ground slot on the PI.
Perhaps obvious things to those who are a bit more experience, but neither seemed obvious to me.
I'm looking forward to tomorrow morning's shot. Thanks again, Greg!
The grounding issue popped up again when I had an monitor plugged in through HMDI and a keyboard through USB. Removing them and SSHing in resolved the issue.
Hi @gabrielDiaz-performlab , that error is telling your that your thermocouple wiring is short-circuiting somewhere. I'd recommend checking how you are securing your thermocouple tip to the boiler.
When working on this project, I also noticed that improper installation of the thermocouple tip (e.g., damaged insulation around the tip due to pinching the tip too hard with a metal fastener) could trigger this error. Make sure that the 2 ends of the thermocouple tip are not connected anywhere other than the "hot junction". If you are using some sort of conductive metal fastener to secure the tip to the boiler, be sure to wrap the tip in some insulator, like scotch tape, first. This thermocouple is anb example of a good quality one that comes with a pre-insulated tip.
If none of the above helps, you may have from a bad MAX31855 or thermocouple. I highly doubt that your error is due to your usb/hdmi/power connections.
Just a heads up that I did end up getting this working, despite noise that I cannot seem to account for. Thank you very much for your hard work! After manually tuning my controller, I have the Silvia up to target temp in about 5 mins, with only a minor overshoot and recovery. It is also very quick to return to temp after a shot has been pulled. Ideal. Beautiful. Delicious.
fantastic!