MAX6675

Cold-Junction-Compensated K-Thermocouple-to-Digital Converter (0°C to +1024°C).

Dependencies

• controlhal

Max6675

The Max6675 class uses a SPI object and a chip-select pin to handle communications:

from machine import Pin, SPI
from max6675 import Max6675

spi = SPI(0, mosi=Pin(3, Pin.OUT), miso=Pin(4, Pin.IN), sck=Pin(2, Pin.OUT))
max6675 = Max6675(spi, cs=Pin(5, Pin.OUT))
temperature_celsius = max6675.read()

The MAX6675 can be polled with a minimum period of 0.22 seconds. Max6675 inherits from the controlhal.Sensor class, so it inherits some of it's benefits, such as caching the previous temperature value if reads are attempted faster than the 0.22 second period.

If the thermocouple becomes disconnected during operation, the next read will cause a OpenThermocouple exception to be raised:

from max6675 import OpenThermocouple

try:
    temperature_celsius = max6675.read()
except OpenThermocouple:
    print("Thermocouple disconnected!")

The MAX6675 must be physically reset after the thermocouple has been reconnected.