Temperature Monitor issues when combined with Serial communication

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21

But, why 9? I just have 8 channels so 8 alphabets to denote them on my LCD.

What am I missing here?

22

It a string. the complier wants to append the null chatacter '\0' to the end of the string.

https://docs.arduino.cc/language-reference/en/variables/data-types/string/

23

I still have no clue, why the Serial communication isnā€™t working. Does have something to do with the adafruit MAX6675 library? I looked into the header file to see if I have mixed any pin labels but, doesnā€™t seem to be the case.

But, I guess other have also faced similar issues. For example, this seems related.

24

Are you still claiming that all 8 work if you use external power and only 4 work if you use USB power?

25

If you only connect 4 at a time does both groups of 4 work?

26

@fracton314

Which version of the Adafruit MAX6675 library do you have?

Which version of the LiquidCrystal_I2C library do you have?

27

Iā€™m using Adafruit MAX6675ā€™s v1.1.0 and LiquidCrystal_I2C v2.0.0

I guess it has something do with the pins 3, 5, 6, 9. The CS lines connected on these pins donā€™t work when connected with a PC whether I have a Serial connection established or not. These also happen to be the PWM pins on the arduino board. Could this be an issue?

28

Spock would say ā€œfascinatingā€, however I cannot explain it.

The MAX6675 is not sold anymore by Adafruit, the library is not maintained anymore, the latest version is 1.1.2 which is technically identical to 1.1.0. Looking into the code I see no bugs. It does not use SPI transactions which in itself should not cause problems.

You could try my MAX6675 library, it allows to set a (microsecond) delay around the pulses and might give some more status information.

Can you provide a link to your version used?

GitHub - johnrickman/LiquidCrystal_I2C: LiquidCrystal Arduino library for the DFRobot I2C LCD displays seems to be 8yrs old (V1.1.4)

GitHub - fdebrabander/Arduino-LiquidCrystal-I2C-library: Library for the LiquidCrystal LCD display connected to an Arduino board. is archived

29

How have you verified this?
Did you use a scope and a test program?

30

Yes. The program seems to be working fine.

The issue was with the grounding. We realised this when we saw that some of the thercouple joints where accidentally getting grounded. The thermocouple lines need to be sheilded to prevent it from getting grounded, to prevent them from interfering with the GND line of MAX6675 chips.

31

I did say that you had a hardware issue two days ago.
See post #19

As I said, that library reports NaN if a thermocouple is disconnected.

32

You were spot on about the hardware issue. However, the thermocouples showed -0 and not NaN, that misled for a while into thinking that it was an issue with the way I was using the pins on the Arduino board.