Go Down

Topic: Ktype thermocouple UNO/LilyPad difference (Read 264 times) previous topic - next topic

mkrsjak

Hello everybody,
I have a small project utilizing a standard K-TYPE thermocouple sensor.
Everything works fine, but when moving the code to LilyPad from UNO
(cause need more space) the temperature readings get wrong (about 20 degrees less than
when using UNO)
any idea why is this hapenning?
The code is the same, sensor probe the same, the readings are different.
I'm using the MAX7765 Thermocouple Library for Arduino.

robtillaart

Assuming the code is the same?

Can you send a link to the MAX7765 Thermocouple Library used? (or post it)

First though that comes up is that there is a (small) difference in power supply.
You might check that with a DMM. 
Rob Tillaart

Nederlandse sectie - http://arduino.cc/forum/index.php/board,77.0.html -
(Please do not PM for private consultancy)

mkrsjak

thanks for answer,
the library is here : https://github.com/JChristensen/Thermocouple/blob/master/Thermocouple.cpp
tested on boiling water on the UNO, reading good.

The LilyPad has a different power source (not USB), but I wonder, these readings should
be independent on the small voltage changes (SPI BUS) aren't they?

Peter_I

Does it use a reference voltage?

In that case, is it the same reference voltage on the two boards?
Bob Pease: "My favorite programming language is ... solder."

mkrsjak

It uses the  SPI library and makes use of SPI_CLOCK_DIV16, SPI_MODE1 and MSBFIRST constants.
The only thing that might be different is the clock divider, as LilyPad uses 8MHz instead of 16.
Since it reads the sensor, and the SPI is a serial protocol, nothing points to a voltage problem
(At least from my little knowledge).

Go Up