search

greencardigan / TC4-shield

78 stars 71 forks source link

Probes not recognized? #10

Open oliverschirmer opened 2 years ago

oliverschirmer commented 2 years ago

Hi, long time since something happend here. Hope i'm not disturbing the silence :) Got my setup a while ago and wanted to resume roasting...

TC4Shield + Arduino UNO via USB to Artisan Roaster Scope (via Ubuntu 22.04 LTS) 3 working Type-K probes with the socket removed. (Tested on an other temp device)

I got a valid read out if the TC4 with the probes disconnected. 26-27°C ambient temp.. Touching the green clamps for probes makes the read out rise to 30°C... as expected.

Connecting the probes and activating the data collection still shows the ambient temp. Touching the green clamps makes the temp rise. Touching the probes end won't make a change. I tested all channels with both polarities and different probes.

How do I debug from here?

Thanks a lot! Oliver

greencardigan commented 2 years ago

Hi, If your thermocouples are definitely working, the only thing I can think of is the ADC chip isn't working properly.

oliverschirmer commented 2 years ago

Thanks for writing back! Can you elaborate? Why is it sending correct temp data from the "socket" (where the probes get connected to the TC4) if the chip is not working? The ADCs function is to convert analog to digital, right?

How can i verify the status of the components on the board?

I thought it could be a setup issue or because it's version 4.0 (which i forgot to mention...) Replacing the chip is out of my skill level. Maybe I can give it second purpose... use it to automatically open the door of the roasters drum if the drop event is triggered...

Is there a better plattform to continue? This is for coding issues, not a repairing forum, right?

greencardigan commented 2 years ago

The cold junction/ambient temperature is measured by the small temperature sensor chip with 5 pins located just behind the thermocouple connectors. Then the voltage across the thermocouple is measured by the ADC and is converted to a temperature, then added to the cold junction temperature to get the thermocouple temperature. So getting ambient temperature readings only confirms that the cold junction temperature sensor is working.

Version 4 may not have the small capacitors that help protect the ADC.

It seems strange that all channels aren't working. Have you got any different thermocouples to try?

Probably best to ask on the homeroasters.org forum. Maybe this thread. https://homeroasters.org/forum/viewthread.php?thread_id=2180

renatoa commented 2 years ago

@oliver, what you mean by " Touching the green clamps"... is this the same as "the "socket" (where the probes get connected"? What's the point to test by touching that area, are you trying to induce a shift of the cold junction temperature ?

@greencardigan, is not strange that all behave the same, on the chip it's only an unique ADC, whose inputs are multiplexed.