397 lines
12 KiB
Python
397 lines
12 KiB
Python
# SPDX-FileCopyrightText: 2018 Carter Nelson for Adafruit Industries
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#
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# SPDX-License-Identifier: MIT
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"""
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`adafruit_bmp3xx`
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====================================================
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CircuitPython driver from BMP388 Temperature and Barometric Pressure sensor.
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* Author(s): Carter Nelson
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Implementation Notes
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--------------------
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**Hardware:**
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* `Adafruit BMP388 - Precision Barometric Pressure and Altimeter
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<https://www.adafruit.com/product/3966>`_ (Product ID: 3966)
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**Software and Dependencies:**
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* Adafruit CircuitPython firmware for the supported boards:
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https://circuitpython.org/downloads
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* Adafruit's Bus Device library:
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https://github.com/adafruit/Adafruit_CircuitPython_BusDevice
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"""
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import struct
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import time
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# from micropython import const
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def const(x): return x
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__version__ = "0.0.0-auto.0"
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__repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_BMP3XX.git"
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_BMP388_CHIP_ID = const(0x50)
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_BMP390_CHIP_ID = const(0x60)
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# pylint: disable=import-outside-toplevel
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_REGISTER_CHIPID = const(0x00)
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_REGISTER_STATUS = const(0x03)
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_REGISTER_PRESSUREDATA = const(0x04)
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_REGISTER_TEMPDATA = const(0x07)
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_REGISTER_CONTROL = const(0x1B)
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_REGISTER_OSR = const(0x1C)
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_REGISTER_ODR = const(0x1D)
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_REGISTER_CONFIG = const(0x1F)
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_REGISTER_CAL_DATA = const(0x31)
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_REGISTER_CMD = const(0x7E)
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_OSR_SETTINGS = (1, 2, 4, 8, 16, 32) # pressure and temperature oversampling settings
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_IIR_SETTINGS = (0, 2, 4, 8, 16, 32, 64, 128) # IIR filter coefficients
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class BMP3XX:
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"""Base class for BMP3XX sensor."""
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def __init__(self):
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chip_id = self._read_byte(_REGISTER_CHIPID)
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if chip_id not in (_BMP388_CHIP_ID, _BMP390_CHIP_ID):
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raise RuntimeError("Failed to find BMP3XX! Chip ID 0x%x" % chip_id)
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self._read_coefficients()
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self.reset()
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self.sea_level_pressure = 1013.25
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self._wait_time = 0.002 # change this value to have faster reads if needed
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"""Sea level pressure in hPa."""
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@property
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def pressure(self):
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"""The pressure in hPa."""
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return self._read()[0] / 100
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@property
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def temperature(self):
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"""The temperature in degrees Celsius"""
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return self._read()[1]
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@property
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def altitude(self):
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"""The altitude in meters based on the currently set sea level pressure."""
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# see https://www.weather.gov/media/epz/wxcalc/pressureAltitude.pdf
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return 44307.7 * (1 - (self.pressure / self.sea_level_pressure) ** 0.190284)
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@property
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def pressure_oversampling(self):
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"""The pressure oversampling setting."""
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return _OSR_SETTINGS[self._read_byte(_REGISTER_OSR) & 0x07]
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@pressure_oversampling.setter
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def pressure_oversampling(self, oversample):
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if oversample not in _OSR_SETTINGS:
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raise ValueError("Oversampling must be one of: {}".format(_OSR_SETTINGS))
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new_setting = self._read_byte(_REGISTER_OSR) & 0xF8 | _OSR_SETTINGS.index(
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oversample
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)
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self._write_register_byte(_REGISTER_OSR, new_setting)
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@property
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def temperature_oversampling(self):
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"""The temperature oversampling setting."""
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return _OSR_SETTINGS[self._read_byte(_REGISTER_OSR) >> 3 & 0x07]
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@temperature_oversampling.setter
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def temperature_oversampling(self, oversample):
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if oversample not in _OSR_SETTINGS:
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raise ValueError("Oversampling must be one of: {}".format(_OSR_SETTINGS))
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new_setting = (
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self._read_byte(_REGISTER_OSR) & 0xC7 | _OSR_SETTINGS.index(oversample) << 3
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)
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self._write_register_byte(_REGISTER_OSR, new_setting)
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@property
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def filter_coefficient(self):
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"""The IIR filter coefficient."""
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return _IIR_SETTINGS[self._read_byte(_REGISTER_CONFIG) >> 1 & 0x07]
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@filter_coefficient.setter
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def filter_coefficient(self, coef):
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if coef not in _IIR_SETTINGS:
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raise ValueError(
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"Filter coefficient must be one of: {}".format(_IIR_SETTINGS)
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)
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self._write_register_byte(_REGISTER_CONFIG, _IIR_SETTINGS.index(coef) << 1)
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def reset(self):
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"""Perform a power on reset. All user configuration settings are overwritten
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with their default state.
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"""
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self._write_register_byte(_REGISTER_CMD, 0xB6)
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def _read(self):
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"""Returns a tuple for temperature and pressure."""
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# OK, pylint. This one is all kinds of stuff you shouldn't worry about.
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# pylint: disable=invalid-name, too-many-locals
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# Perform one measurement in forced mode
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self._write_register_byte(_REGISTER_CONTROL, 0x13)
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# Wait for *both* conversions to complete
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while self._read_byte(_REGISTER_STATUS) & 0x60 != 0x60:
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time.sleep(self._wait_time)
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# Get ADC values
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data = self._read_register(_REGISTER_PRESSUREDATA, 6)
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adc_p = data[2] << 16 | data[1] << 8 | data[0]
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adc_t = data[5] << 16 | data[4] << 8 | data[3]
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# datasheet, sec 9.2 Temperature compensation
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T1, T2, T3 = self._temp_calib
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pd1 = adc_t - T1
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pd2 = pd1 * T2
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temperature = pd2 + (pd1 * pd1) * T3
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# datasheet, sec 9.3 Pressure compensation
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P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11 = self._pressure_calib
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pd1 = P6 * temperature
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pd2 = P7 * temperature ** 2.0
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pd3 = P8 * temperature ** 3.0
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po1 = P5 + pd1 + pd2 + pd3
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pd1 = P2 * temperature
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pd2 = P3 * temperature ** 2.0
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pd3 = P4 * temperature ** 3.0
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po2 = adc_p * (P1 + pd1 + pd2 + pd3)
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pd1 = adc_p ** 2.0
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pd2 = P9 + P10 * temperature
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pd3 = pd1 * pd2
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pd4 = pd3 + P11 * adc_p ** 3.0
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pressure = po1 + po2 + pd4
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# pressure in hPa, temperature in deg C
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return pressure, temperature
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def _read_coefficients(self):
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"""Read & save the calibration coefficients"""
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coeff = self._read_register(_REGISTER_CAL_DATA, 21)
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# See datasheet, pg. 27, table 22
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coeff = struct.unpack("<HHbhhbbHHbbhbb", coeff)
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# See datasheet, sec 9.1
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# Note: forcing float math to prevent issues with boards that
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# do not support long ints for 2**<large int>
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self._temp_calib = (
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coeff[0] / 2 ** -8.0, # T1
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coeff[1] / 2 ** 30.0, # T2
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coeff[2] / 2 ** 48.0,
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) # T3
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self._pressure_calib = (
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(coeff[3] - 2 ** 14.0) / 2 ** 20.0, # P1
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(coeff[4] - 2 ** 14.0) / 2 ** 29.0, # P2
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coeff[5] / 2 ** 32.0, # P3
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coeff[6] / 2 ** 37.0, # P4
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coeff[7] / 2 ** -3.0, # P5
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coeff[8] / 2 ** 6.0, # P6
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coeff[9] / 2 ** 8.0, # P7
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coeff[10] / 2 ** 15.0, # P8
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coeff[11] / 2 ** 48.0, # P9
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coeff[12] / 2 ** 48.0, # P10
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coeff[13] / 2 ** 65.0,
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) # P11
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def _read_byte(self, register):
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"""Read a byte register value and return it"""
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return self._read_register(register, 1)[0]
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def _read_register(self, register, length):
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"""Low level register reading, not implemented in base class"""
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raise NotImplementedError()
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def _write_register_byte(self, register, value):
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"""Low level register writing, not implemented in base class"""
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raise NotImplementedError()
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class BMP3XX_I2C(BMP3XX):
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"""Driver for I2C connected BMP3XX.
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:param ~busio.I2C i2c: The I2C bus the BMP388 is connected to.
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:param int address: I2C device address. Defaults to :const:`0x77`.
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but another address can be passed in as an argument
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**Quickstart: Importing and using the BMP388**
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Here is an example of using the :class:`BMP3XX_I2C` class.
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First you will need to import the libraries to use the sensor
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.. code-block:: python
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import board
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import adafruit_bmp3xx
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Once this is done you can define your `board.I2C` object and define your sensor object
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.. code-block:: python
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i2c = board.I2C() # uses board.SCL and board.SDA
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bmp = adafruit_bmp3xx.BMP3XX_I2C(i2c)
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Now you have access to the :attr:`temperature` and :attr:`pressure` attributes
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.. code-block:: python
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temperature = bmp.temperature
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pressure = bmp.pressure
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"""
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def __init__(self, i2c, address=0x77):
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from adafruit_bus_device import i2c_device
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self._i2c = i2c_device.I2CDevice(i2c, address)
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super().__init__()
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def _read_register(self, register, length):
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"""Low level register reading over I2C, returns a list of values"""
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result = bytearray(length)
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with self._i2c as i2c:
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i2c.write(bytes([register & 0xFF]))
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i2c.readinto(result)
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return result
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def _write_register_byte(self, register, value):
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"""Low level register writing over I2C, writes one 8-bit value"""
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with self._i2c as i2c:
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i2c.write(bytes((register & 0xFF, value & 0xFF)))
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class BMP3XX_SPI(BMP3XX):
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"""Driver for SPI connected BMP3XX.
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:param ~busio.SPI spi: SPI device
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:param ~digitalio.DigitalInOut cs: Chip Select
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**Quickstart: Importing and using the BMP388**
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Here is an example of using the :class:`BMP3XX_SPI` class.
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First you will need to import the libraries to use the sensor
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.. code-block:: python
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import board
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import adafruit_bmp3xx
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from digitalio import DigitalInOut, Direction
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Once this is done you can define your `board.SPI` object and define your sensor object
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.. code-block:: python
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spi = board.SPI()
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cs = DigitalInOut(board.D5)
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bmp = adafruit_bmp3xx.BMP3XX_SPI(spi, cs)
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Now you have access to the :attr:`temperature` and :attr:`pressure` attributes
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.. code-block:: python
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temperature = bmp.temperature
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pressure = bmp.pressure
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"""
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def __init__(self, spi, cs):
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from adafruit_bus_device import spi_device
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self._spi = spi_device.SPIDevice(spi, cs)
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# toggle CS low/high to put BMP3XX in SPI mode
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with self._spi:
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time.sleep(0.001)
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super().__init__()
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def _read_register(self, register, length):
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"""Low level register reading over SPI, returns a list of values"""
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result = bytearray(length)
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with self._spi as spi:
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# pylint: disable=no-member
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spi.write(bytes((0x80 | register, 0x00)))
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spi.readinto(result)
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return result
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def _write_register_byte(self, register, value):
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"""Low level register writing over SPI, writes one 8-bit value"""
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with self._spi as spi:
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# pylint: disable=no-member
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spi.write(bytes((register & 0x7F, value & 0xFF)))
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#
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from i2cdriver import I2CDriver
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import sys
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class BMP3XX_I2CDriver(BMP3XX):
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"""Driver for I2CDriver connected BMP3XX.
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:param ~busio.I2C i2c: The I2CDriver the BMP388 is connected to.
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:param int address: I2C device address. Defaults to :const:`0x77`.
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but another address can be passed in as an argument
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**Quickstart: Importing and using the BMP388**
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Here is an example of using the :class:`BMP3XX_I2CDriver` class.
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First you will need to import the libraries
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.. code-block:: python
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from i2cdriver import I2CDriver
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import adafruit_bmp3xx
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Once this is done you can connect to the I2CDriver and define the sensor object, e.g.
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.. code-block:: python
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i2c = I2CDriver("COM9")
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bmp = adafruit_bmp3xx.BMP3XX_I2C(i2c)
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Now you have access to the :attr:`temperature` and :attr:`pressure` attributes
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.. code-block:: python
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temperature = bmp.temperature
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pressure = bmp.pressure
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"""
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def __init__(self, i2c, address=0x77):
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self.i2c = i2c
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self.a = address
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super().__init__()
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def _read_register(self, register, length):
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"""Low level register reading over I2C, returns a list of values"""
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return self.i2c.regrd(self.a, register, length)
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def _write_register_byte(self, register, value):
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"""Low level register writing over I2C, writes one 8-bit value"""
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self.i2c.regwr(self.a, register, value)
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if __name__ == '__main__':
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i2 = I2CDriver(sys.argv[1])
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d = BMP3XX_I2CDriver(i2)
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d.pressure_oversampling = 32
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d.temperature_oversampling = 32
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while 1:
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(pressure, temperature) = d._read()
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print(f"Pressure: {pressure / 100:.2f} hPa")
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print(f"Temperature: {temperature:.2f} C")
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