MarkTilles

Back in Sweden I built a nicely running controller from jbruces early GitHub posts, helped him enhance the code for the better thermocouple board, added many new features and tweaks and it’s been running reliably for three years without a hiccup. I now help my friend in Sweden manage it from the USA via CPN. I moved last year to LA and tomorrow am picking up a kiln … and plan on building another. I have my last code branch on GitHub as well. Mark

I have cheap 40A SSRs from Banggood and Wish and am not having any off issues with my operations, even with 15 foot long cables strung all over the place. Very stable measurements, no operational errors I’ve seen. Just lucky maybe?

Ah!! That’s why my use of DPDT toggle switches to switch between two different kiln thermocouple cables and a terminal block is still providing reliable results! Thanks for this!

No problem I use Mac for my hobbies as well. Just use the raspberry pi imager tool and select my file as the source image to write onto your sd card. I can send a link you can download the image from my OneDrive. But I need to genericize it first. Please note my image has features not in Jbruce’s fork (not to mention a link to swapping between two instances of the kiln controller located in two separate folders). I use the same hardware to control two different kilns with toggle switches to swap between thermocouples- and this is working for me … Email me at markt3ATATATATtilles.net

Rondoc, i have a working ISO image of 7.5 GB card I can share with you on MS OneDrive. It’s set up with a Pi zero w and max31856 if you might want to give it a whirl? (But I can’t get to it until next week, need to change passwords etc first). Send me your email address if you’d like to give it a try

What country are you in? My only thought is to send your board to someone else that has a working system to plug it in and see if it works there. I suspect the hardware. Like I said, I followed Jason’s instructions to the tee and had absolutely no trouble getting my clean test install to work. You might also try without using the hat, or try using a complete second set of cables, every connection you make is a potential connection point that could go wrong.

I would, yes.

That’s how they should look.

Looks to me like some of your solder joints are VERY cold. I would bet your problem lies right there. You might want to recheck them, maybe desolder and put on new solder with some flux.

I should’ve clarified that those red lines in my sketch are where I cut the traces, so GPI05 is going all the way around to the other pin that I show on the diagram. The same thing with the other pin on the other side.

In my ugly sketch above, I show the PIN numbers of the pi zero w, not GPIO numbers on the top. Below on each pin definition on the Max board I mentioned the GPIO numbers these connections represent. Vän here is my config file except for my heating GPIO ### Thermocouple Adapter selection: # max31855 - bitbang SPI interface # max31856 - bitbang SPI interface. must specify thermocouple_type. max31855 = 0 max31856 = 1 # see lib/max31856.py for other thermocouple_type, only applies to max31856 thermocouple_type = MAX31856.MAX31856_S_TYPE ### Thermocouple Connection gpio_sensor_cs = 5 gpio_sensor_clock = 11 gpio_sensor_data = 9 gpio_sensor_di = 10 # only used with max31856

Good point, but I’m waiting for a 12 V DC electromagnet version, and I’m going to run it from an old computer power supply have in the garage.

Personally I’m using GPIO 17. But I can also use 16, 22 or 27 which I’ve also wired in and am currently blinking LEDs and switching SSR relays on for fun! I still need to finish designing and then print out a new chassis to put everything into before I swap this one out with my current production unit. I’m also waiting for an electromagnet lock mechanism to put into my ceramic room door jamb :-)

I wanted to be able to easily replace my max31856 in case of failure and easily connect or disconnect auxiliary devices, so I made a board with socket and pins to connect devices. I have four GPIOs pulled down and two pulled up so I can interface other functions with the outside world more than just the heater control output. You can see how I am using two single-sided boards mounted opposite each other, was a little tricky but managed to get it working. Having wired in extra GPIO ports also gives me the option of shifting the heating control port to another GPIO in case of one port failure.

Guys I don’t know what the problem is. I just took a fresh installation of pi OS (The default 32-bit Debian Bullseye with desktop option) from the raspberry pi imager, enabled SSH and VNC, connected with VNC and followed all the set up prompts including updating the system. I next followed Jason’s instructions to the tee. I ran start-on boot, rebooted, and am using the exact same hardware I’ve been using earlier with an S-type thermocouple and my adafruit max31856, everything works perfectly. Could someone be wiring up the interface card wrong? Here’s my sketch connecting the max31856 to my pi zero w, it’s ugly but you get the idea. Please note: the red lines are where I have cut the traces on my circuit board, so that the wires for those pins go all the way around to the other round two other pins on the pi

Might this help you? Grepped for 31856 ./kiln-controller/lib/max31856.py ./kiln-controller/lib/__pycache__/max31856.cpython-37.pyc ./usr/lib/modules/5.10.63+/kernel/drivers/iio/temperature/max31856.ko ./usr/lib/modules/5.10.63-v8+/kernel/drivers/iio/temperature/max31856.ko ./usr/lib/modules/5.10.63-v7l+/kernel/drivers/iio/temperature/max31856.ko ./usr/lib/modules/5.10.63-v7+/kernel/drivers/iio/temperature/max31856.ko

You know, to be perfectly honest, I will have a hard time answering your questions. I have basically been cloning the same system since the start that I had working, except for the kiln controller folder. I have been updating that folder now and then from Jasons source but I haven’t done that in probably three or four months now. I’ve just been adding a lot of tweaks for my own use, including the scheduled start which my friend Marko helped me with. If there is some folder that I could zip up for you and send to you, let me know. But I am just hacking my way along.

Newsps, i’ve been using the max 31856 for a good year ever since Jason Bruce helped me with the coding. Works great for me, I’m using S thermocouples with both ovens I have connected to my system. I bought the adafruit max31856 card from a reseller here in Europe

I just want to share that through my friend Marko (who is a real programmer) and I have finally uploaded the code to add scheduled firings into Jason’s project. Hopefully this can soon get tested and implemented, then we will continue on to add some of my other improvements that I feel I would like to share with the group.

Thank you I will share this with my friend and we will do a little studying.

No, we are newbie amateurs, but we’ve been getting satisfactory results with our work nevertheless. We have fired many times in the past with this oven with the same clay type, and I’m confident we reach the same temperatures because I had compared top temperature is between the system earlier. But heat work, that’s new for us and something we will be looking into, especially to be able to create good, effective heating curves with the oven. I guess that’s the idea right? Making sure that the proper heat work is being applied to the material.

Yes! I haven’t opened the oven yet, but will do that tonight. The system operated very well, pretty much exactly as it is designed. I had the catch-up setting turned on to 10°, and my oven was going very slowly toward the end only about 80 to 90 C per hour, so because the catch up was on I didn’t get 1260 in the oven I only got 1250 because the system shuts off at the target temperature nevertheless, it apparently doesn’t wait for the sensor temperature. So now I know I’m going to change that catch up setting to 1° instead of 10. I don’t know if it can be changed to zero? At that point I tried to restart the system with a new configuration to get that last 10°, but for some reason I was unable to start it. It showed in the GUI Interface that the system restarted, but nothing was showing up in the logs nor did the red heating lamp start to blink. I had to shut down and restart the service get the system to restart, I don’t know why. But by that point I had lost so much heat I decided it was good enough at 1250 for the stoneware firing without glaze.

My first Raspberry Pi/max31856/S-thermocoupe/1260C stoneware burn is in progress, and it's going flawlessly!

You know, I was thinking, if somewhere in the config file you might have a typographical error, it might be that the kiln engine has miss-read that variable setting of yours. And maybe others? I would first take a close look for this. Next you might want to test again without the heater relay/SSRs attached, and see if you can re-create the problem. You might then copy in an unmodified version of the config file, and then make your changes, and test again and see if the problem is gone.

So for you the countdown timer that shows how much time is estimated remaining in the process continued moving even though the oven couldn’t keep up with the curve?