MicroPython MPRLS library

mprls.py

# MicroPython library for the Adafruit MPRLS/Honeywell MPR LS module.
# 22/10/2023 - Taylor Robinson (https://robins.one)
# Example:
"""
from machine import I2C, Pin
from mprls import MPRLS

i2c = I2C(id=1,sda=Pin(26),scl=Pin(27))
mprls = MPRLS(i2c)

print(mprls.getPressure())
"""


MPRLS_STATUS_POWERED = 0x40
MPRLS_STATUS_BUSY = 0x20
MPRLS_STATUS_FAILED = 0x04
MPRLS_STATUS_MATHSAT = 0x02

PSI_TO_HPA = 68.947572932


class MPRLS:
    def __init__(self, i2c, address=0x18):
        self._i2c = i2c
        self._address = address
        self._buffer = bytearray(4)

        if not self.readStatus() & MPRLS_STATUS_POWERED:
            raise RuntimeError("MPRLS not found")
    
    def read(self):
        """
        Reads the sensor's registers into the _buffer.
        """
        self._i2c.readfrom_into(self._address, self._buffer)
    
    def readStatus(self):
        """
        Reads the status of the sensor.
        """
        self.read()
        return self._buffer[0]
    
    def requestPressure(self):
        """
        Requests that the sensor take a pressure reading.
        """
        self._buffer[0] = 0xAA
        self._buffer[1] = 0x00
        self._buffer[2] = 0x00
        self._i2c.writeto(self._address, self._buffer[0:3])

    def readPressure(self, multi=PSI_TO_HPA):
        """
        Reads pressure from the sensor.
        Arguments:
            multi: Multiplier to convert PSI to desired unit. Default is 68.947572932 to convert to hPa. Set to 1 to get PSI.
        Returns:
            - False if the sensor is busy
            - -1 if there was an error
            - or the pressure in the desired unit.
        """
        status = self.readStatus()
        if status & MPRLS_STATUS_BUSY:
            return False
        if status & MPRLS_STATUS_FAILED or status & MPRLS_STATUS_MATHSAT:
            return -1
        rawPSI = self._buffer[1] << 16 | self._buffer[2] << 8 | self._buffer[3]

        psi = (rawPSI - 0x19999A) * 25
        psi /= 0xE66666 - 0x19999A
        return psi * multi

    def getPressure(self, multi=PSI_TO_HPA):
        """
        Requests pressure and waits for it to be ready.
        Arguments:
            multi: Multiplier to convert PSI to desired unit. Default is 68.947572932 to convert to hPa. Set to 1 to get PSI.
        Returns:
            Pressure in desired unit, or -1 if there was an error.
        """
        self.requestPressure()
        pres = self.readPressure(multi)
        while pres == False:
            pres = self.readPressure(multi)
        return pres