Building the hardware - Pete-C2/Multi-Channel-Temperature-Monitor GitHub Wiki

See the schematic diagram in the project file.

For each channel you will need one MAX31855 IC (integrated circuit) matched to your sensor type. Most likely you will use K-type sensor so use MAX31855K ICs.

The circuit is quite simple - see the datasheet https://datasheets.maximintegrated.com/en/ds/MAX31855.pdf. Follow the application circuit and in addition consider putting a 10nF capacitor across the sensor input (it can be recommended according to other Maxim notes).

• All SO pins (data) go to one Raspberry Pi GPIO.
• All SCK pins (clock) go to one Raspberry Pi GPIO.
• All CS pins (chip select) go to their own Raspberry Pi GPIO. In addition since these are active low, unless you can guarantee that the pins will never go low together then add a pull-up resistor (I'm going to try something like 4.7kΩ). The Raspberry Pi has a couple of pins (3 & 5 on the header) that have built-in resistors so you don't need to bother for these.

Power the circuit from the 3.3V rail - definitely avoid the 5V rail as that is too high for the IC.
Add a 100nF capacitor across the power pins of each IC and you should be good to go.
I have 12 sensors and from one side of the 40-pin header (odd numbered pins) there are enough signals to run all of these.