Author Topic: ESP32 - MAX6675 Thermocouple Tests and Experiments  (Read 214 times)

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Offline jcrubin

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ESP32 - MAX6675 Thermocouple Tests and Experiments
« on: October 07, 2019, 12:07:19 pm »
Today we do some testing on the MAX6675 that I'd picked up on Banggood.  I need a few of these for several projects, though I haven't settled on which type or what yet, I figured I would capture some tests in a video today and go way overboard on the unnecessaries.  Everything I do is with the ESP32; not actually owning an Arduino, my assumption is that this will work just the same, given the simplicity of todays tasks.

     The wiring is straight forward, I went with the 3.3 volt but its good to know that 5v is also a possibility straight off a power supply.   I was surprised to see that the Adafruit library wont work for the ESP32, and I went with the one from Yurii Salimov, it worked just fine, designed exactly around the chip specification.

     Apparently it would seem that Red goes to + and Blue to -.  This is not immediately evident.  Testing with a supplied example from the library showed sadly that my flir camera may be off a few degrees, I should check that out.  My other thermometer confirms that the probe is off just a few degrees.

     The first task was to assemble a program using PWM to use the blue LED on the ESP32 as a temperature indicator.  I did this without map just to demonstrate whats going on.  It works but not smooth because the range I was working in did not provide for wonderful resolution, also there is no secondary sensor to hold the base temperature value, so this method is flawed.

     Instead I employed a PCM9685 driver board and a servo, mapping 0 to 100 degrees to the full throw of the servo.  In this manner i could mount a cardboard display behind the servo and mark every 5 degrees celsius.  With this, a Rube Goldberg Analogue thermometer is produced.  It did work surprisingly well though, and demonstrates that this has great potential for  automatic regulation at the output, given the input with little effort  Consider that servo could be adjusting the gas at the lighter to maintain an ideal pre-set temperature.

     Well, thats enough fun for one afternoon, more ESP32 stuff in the future.


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