Re: MAX31855 problem - reads zero

by paddygoat on Wed Jul 03, 2013 8:44 am

Lastly (hopefully) there are two very strange symbols on the LCD screen after the Int. Temp numbers. I'm getting 2 numbers then the decimal point then 2 more numbers and then 2 strange characters. Please advise!
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Re: MAX31855 problem - reads zero

by adafruit_support_bill on Wed Jul 03, 2013 8:53 am

Are they the same characters always? Can you post a photo?
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Re: MAX31855 problem - reads zero

by paddygoat on Wed Jul 03, 2013 9:02 am

characters.jpg
Here's the strange characters spotted in my LCD. Look like they could be japanese?
characters.jpg (49.81 KiB) Viewed 5303 times
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Re: MAX31855 problem - reads zero

by paddygoat on Wed Jul 03, 2013 9:06 am

PS. They dont ever seem to change.
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Re: MAX31855 problem - reads zero

by adafruit_support_rick on Wed Jul 03, 2013 9:21 am

Strange. Could be uninitialized garbage in the display buffer. Try calling lcd.clear() at the end of your setup() routine.
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Re: MAX31855 problem - reads zero

by paddygoat on Wed Jul 03, 2013 9:37 am

Tried it, as below, but no better.
Code: Select all | TOGGLE FULL SIZE
void loop() {
  // basic readout test, just print the current temp
   Serial.print("Internal Temp = ");
   Serial.println(thermocouple.readInternal());

   double c = thermocouple.readCelsius();
   if (isnan(c)) {
     Serial.println("Something wrong with thermocouple!");
   } else {
     Serial.print("C = ");
     Serial.println(c);
   }
   //Serial.print("F = ");
   //Serial.println(thermocouple.readFarenheit());
   lcd.clear();
   lcd.setCursor(0, 0);
   lcd.print("Int. Temp = ");
   lcd.println(thermocouple.readInternal());
   lcd.print("  ");
   lcd.setCursor(0, 1);
   lcd.print("C = ");
   lcd.print(c);
   lcd.print("  ");
 
   delay(1000);
}
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Re: MAX31855 problem - reads zero

by adafruit_support_bill on Wed Jul 03, 2013 9:51 am

The problem is here:
Code: Select all | TOGGLE FULL SIZE
lcd.println(thermocouple.readInternal());

println adds a CR/LF to the end of the string. Use lcd.setcursor() to move to the next line instead.
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Re: MAX31855 problem - reads zero

by paddygoat on Wed Jul 03, 2013 10:30 am

OK thanks, so what exactly is the whole block of LCD code please? Thank you.
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Re: MAX31855 problem - reads zero

by adafruit_support_bill on Wed Jul 03, 2013 11:32 am

Looks like you already have the setCursor() calls in place. So just change that one println() to a print() and you should be fine.
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Re: MAX31855 problem - reads zero

by paddygoat on Wed Jul 03, 2013 11:49 am

Great - that all works! Thank you very much :D PS. There is probably still a lurking problem with accessing the AVR folder which I solved through random library adding.
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Re: MAX31855 problem - reads zero

by adafruit_support_bill on Wed Jul 03, 2013 12:01 pm

...which I solved through random library adding.

You have to be careful about that. The Arduino IDE is fairly fussy about how you organize the libraries and is easily confused by duplicates. You might want to read through this guide: http://learn.adafruit.com/adafruit-all- ... nstall-use
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Re: MAX31855 problem - reads zero

by paddygoat on Wed Jul 03, 2013 12:19 pm

Yes, seems like I got it too work by confusing it!
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Re: MAX31855 problem - reads zero

by paddygoat on Fri Jul 19, 2013 7:05 am

I've got my thermocouple break out board https://www.adafruit.com/blog/2012/11/23/new-product-thermocouple-amplifier-max31855-breakout-board-max6675-upgrade-v2-0/working nicely on my uno :D but now have a problem getting it to work with my own boards:
Image
Image
I spent hours checking the connections over and over again and have concluded that there is something missing, a component perhaps, on my PCB. I was thinking maybe it is something to do with the 16Mhz resonator I am using - is this compatible with the MAX31855? Any help much appreciated.
PS. the LCD reads 0.00 degrees C on both the internal and the probe lines.
PPS. My boards work fine in every other respect.
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Re: MAX31855 problem - reads zero

by adafruit_support_bill on Fri Jul 19, 2013 7:36 am

Nice looking board!
I don't think the use of a resonator is the issue. The Uno also uses a 16MHz resonator to clock the 328P.
http://learn.adafruit.com/arduino-tips- ... no-uno-faq
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Re: MAX31855 problem - reads zero

by paddygoat on Fri Jul 19, 2013 8:06 am

Thanks for the reply, Bill. Glad you like the board. I cant think what the fault is, but I'm going to trawl through some rocket scream schematics to see if I can spot something I've missed.
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