Multiple thermocouple

Hi all

Wondering if Arduino Mega could take up to 6 of the Breakout Board MAX31855 and 3 LCD screens because the number of pins might not be enough

Any input if this is possible ?

Hi,
The MAX31855b has a SPI interface. So you need 2 pins, CLK and DO that can be on the same pins for all the chips. They need individual CS (Chip Select) pins. So that's 8 pins..

If you use I2C LCD DIsplays, they only need 2 pins and if you can get versions where you can change the address, only 2 pins for 3 displays..

You need to understand the devices and their wiring and code.

What temperature range are you looking at ? Anything below 150C would be more accurate/ cheaper and use less pins by using a DS18b20 sensor .

hammy:
What temperature range are you looking at ? Anything below 150C would be more accurate/ cheaper and use less pins by using a DS18b20 sensor .

DS18B20

Operating Temperature Range -55°C to +125°C
±0.5°C Accuracy from -10°C to +85°C
±1.25 °C Accuracy above +85°C

RTD-100

ACTUAL RTD ACCURACY +/- °C
B GRADE A GRADE
-200 °C 1.30 °C 0.55 °C
-150 °C 1.05 °C 0.45 °C
-100 °C 0.80 °C 0.35 °C
-90 °C 0.75 °C 0.33 °C
-80 °C 0.70 °C 0.31 °C
-70 °C 0.65 °C 0.29 °C
-60 °C 0.60 °C 0.27 °C
-50 °C 0.55 °C 0.25 °C
-40 °C 0.50 °C 0.23 °C
-30 °C 0.45 °C 0.21 °C
-20 °C 0.40 °C 0.19 °C
-10 °C 0.37 °C 0.17 °C
0 °C 0.30 °C 0.15 °C
10 °C 0.35 °C 0.17 °C
20 °C 0.40 °C 0.19 °C
30 °C 0.45 °C 0.21 °C
40 °C 0.50 °C 0.23 °C
50 °C 0.55 °C 0.25 °C
60 °C 0.60 °C 0.27 °C
70 °C 0.65 °C 0.29 °C
80 °C 0.70 °C 0.31 °C
90 °C 0.75 °C 0.33 °C
100 °C 0.80 °C 0.35 °C
110 °C 0.85 °C 0.37 °C
120 °C 0.90 °C 0.39 °C
130 °C 0.95 °C 0.41 °C
140 °C 1.00 °C 0.43 °C
150 °C 1.05 °C 0.45 °C

Oh dear..

The OP said thermocouple not RTD . Thermocouples are lousy at low temperature , have a curved response, and need CJC. Hence my suggestion , that if it were low temp an 1820 is ideal .

The figures you give are for an RTD sensor, without lead wires amplifier etc , which adds errors before you have a system . Those for the 1820 are total “system” error . You can’t compare the two like that !!

The chip he mentions is a thermocouple amplifier , covers a wider temp range and is +- 2C; so system error with an RTD is about -/+ 2.3C .