MAX6675 micropython driver. Tested on ESP32 WROOM

max6675.py

from machine import Pin
import utime

class MAX6675():
    def __init__(self, so_pin=21, cs_pin=22, sck_pin=23):
        self.cs = Pin(cs_pin, Pin.OUT)
        self.so = Pin(so_pin, Pin.IN)
        self.sck = Pin(sck_pin, Pin.OUT)

        self.cs.on()
        self.so.off()
        self.sck.off()

        self.last_read_time = utime.ticks_ms()

    def readFahrenheit(self):
        return self.readCelsius() * 9.0 / 5.0 + 32

    def readCelsius(self):
        data = self.__read_data()
        volts = sum([b * (1 << i) for i, b in enumerate(reversed(data))])
        print(volts)

        return volts * 0.25

    def __read_data(self):
        # CS down, read bytes then cs up
        self.cs.off()
        utime.sleep_us(10)
        data = self.__read_word() # (self.__read_byte() << 8) | self.__read_byte()
        self.cs.on()

        print(data)
        print(data[1:-3])

        if data[-3] == 1:
            raise NoThermocoupleAttached()

        return data[1:-3]

    def __read_word(self):
        return [self.__read_bit() for _ in range(16)]


    def __read_bit(self):
        self.sck.off()
        utime.sleep_us(10)
        bit = self.so.value()
        self.sck.on()
        utime.sleep_us(10)
        return bit


class NoThermocoupleAttached(Exception):
    """Raised when there is no thermocouple attached to MAX6675"""
    pass

Hello,
These raise in row 38 does not works:
raise NoThermocoupleAttached()

Marton from Budapest

Would you give more information about the issue?

Hello Árpád, First of all thanks for the idea, it was very useful for me. I am a beginner! I think found some mistakes in the program. If not, take my apologies. So when I disconnect the MAX6675 panel from ESP32 WROOM, nothing happens. Otherwise working well if data[-3] == 1: raise NoThermocoupleAttached() Is this row doing nothing?? ****************************************** yes, I changed pins. #def __init__(self, so_pin=21, cs_pin=22, sck_pin=23): def __init__(self, so_pin=19, cs_pin=5, sck_pin=18): ************************************************* I commented out this : #self.last_read_time = utime.ticks_ms() what is it here?? it has no influenced to program.. That's all, Best regards, Márton Árpád Tamási ***@***.***> ezt írta (időpont: 2022. máj. 11., Sze, 17:30):

…

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Disconnect detection was tricky and my solution is not bulletproof at all. Please update me if you find a better solution.
I used last read time for debugging purposes and is not needed at all. Same is true for printing values.