node-alpha / max31855

Raspberry Pi driver for MAX31855/MAX6675 Cold-Junction Compensated Thermocouple-to-Digital Converter

Python driver for MAX31855 Cold-Junction Compensated Thermocouple-to-Digital Converter

Added support for MAX6675 Cold-Junction Compensated K-Thermocouple-to-Digital Converter

Requires:

• The GPIO Library (Already on most Raspberry Pi OS builds)
• A Raspberry Pi

Basic use

#!/usr/bin/python
from max31855 import MAX31855, MAX31855Error

cs_pin = 24
clock_pin = 23
data_pin = 22
units = "f"
thermocouple = MAX31855(cs_pin, clock_pin, data_pin, units)
print(thermocouple.get())
thermocouple.cleanup()

MAX6675 example

#!/usr/bin/python
from max6675 import MAX6675, MAX6675Error

cs_pin = 24
clock_pin = 23
data_pin = 22
units = "c"
thermocouple = MAX6675(cs_pin, clock_pin, data_pin, units)
print(thermocouple.get())
thermocouple.cleanup()

Note: these are the GPIO pin numbers, not the header pin numbers.
This can be overriden by passing GPIO.BOARD as the fifth init parameter.

See max31855.py for a multi-chip example.

Changelog

V3.0

• Added MAX6675 chip support

V2.0

• SPI now done in software
  • Use whatever pins you want for CS, Clock & Data
  • Hardware SPI was limited to only two chip / slave select lines.
    Now use as many chips a you have extra pins!
• Removed quick2wire dependency.
• Removed bitstring dependency; bit extraction and two's complement conversion now done in library.
• Added cleanup() method to be called on close (or destruction of instance), which does a targeted version of GPIO.cleanup().

NOTE: If you were using the previous hardware-based version, you will have to update your code to match the new init function: MAX31855(cs_pin, clock_pin, data_pin, units)

V1.0

• Initial release.