322 lines
10 KiB
Python
322 lines
10 KiB
Python
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from micropython import const
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from ustruct import unpack as unp
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# Author David Stenwall Wahlund (david at dafnet.se)
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# Power Modes
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BMP280_POWER_SLEEP = const(0)
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BMP280_POWER_FORCED = const(1)
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BMP280_POWER_NORMAL = const(3)
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BMP280_SPI3W_ON = const(1)
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BMP280_SPI3W_OFF = const(0)
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BMP280_TEMP_OS_SKIP = const(0)
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BMP280_TEMP_OS_1 = const(1)
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BMP280_TEMP_OS_2 = const(2)
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BMP280_TEMP_OS_4 = const(3)
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BMP280_TEMP_OS_8 = const(4)
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BMP280_TEMP_OS_16 = const(5)
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BMP280_PRES_OS_SKIP = const(0)
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BMP280_PRES_OS_1 = const(1)
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BMP280_PRES_OS_2 = const(2)
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BMP280_PRES_OS_4 = const(3)
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BMP280_PRES_OS_8 = const(4)
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BMP280_PRES_OS_16 = const(5)
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# Standby settings in ms
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BMP280_STANDBY_0_5 = const(0)
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BMP280_STANDBY_62_5 = const(1)
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BMP280_STANDBY_125 = const(2)
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BMP280_STANDBY_250 = const(3)
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BMP280_STANDBY_500 = const(4)
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BMP280_STANDBY_1000 = const(5)
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BMP280_STANDBY_2000 = const(6)
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BMP280_STANDBY_4000 = const(7)
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# IIR Filter setting
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BMP280_IIR_FILTER_OFF = const(0)
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BMP280_IIR_FILTER_2 = const(1)
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BMP280_IIR_FILTER_4 = const(2)
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BMP280_IIR_FILTER_8 = const(3)
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BMP280_IIR_FILTER_16 = const(4)
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# Oversampling setting
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BMP280_OS_ULTRALOW = const(0)
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BMP280_OS_LOW = const(1)
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BMP280_OS_STANDARD = const(2)
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BMP280_OS_HIGH = const(3)
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BMP280_OS_ULTRAHIGH = const(4)
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# Oversampling matrix
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# (PRESS_OS, TEMP_OS, sample time in ms)
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_BMP280_OS_MATRIX = [
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[BMP280_PRES_OS_1, BMP280_TEMP_OS_1, 7],
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[BMP280_PRES_OS_2, BMP280_TEMP_OS_1, 9],
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[BMP280_PRES_OS_4, BMP280_TEMP_OS_1, 14],
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[BMP280_PRES_OS_8, BMP280_TEMP_OS_1, 23],
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[BMP280_PRES_OS_16, BMP280_TEMP_OS_2, 44]
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]
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# Use cases
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BMP280_CASE_HANDHELD_LOW = const(0)
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BMP280_CASE_HANDHELD_DYN = const(1)
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BMP280_CASE_WEATHER = const(2)
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BMP280_CASE_FLOOR = const(3)
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BMP280_CASE_DROP = const(4)
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BMP280_CASE_INDOOR = const(5)
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_BMP280_CASE_MATRIX = [
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[BMP280_POWER_NORMAL, BMP280_OS_ULTRAHIGH, BMP280_IIR_FILTER_4, BMP280_STANDBY_62_5],
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[BMP280_POWER_NORMAL, BMP280_OS_STANDARD, BMP280_IIR_FILTER_16, BMP280_STANDBY_0_5],
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[BMP280_POWER_FORCED, BMP280_OS_ULTRALOW, BMP280_IIR_FILTER_OFF, BMP280_STANDBY_0_5],
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[BMP280_POWER_NORMAL, BMP280_OS_STANDARD, BMP280_IIR_FILTER_4, BMP280_STANDBY_125],
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[BMP280_POWER_NORMAL, BMP280_OS_LOW, BMP280_IIR_FILTER_OFF, BMP280_STANDBY_0_5],
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[BMP280_POWER_NORMAL, BMP280_OS_ULTRAHIGH, BMP280_IIR_FILTER_16, BMP280_STANDBY_0_5]
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]
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_BMP280_REGISTER_ID = const(0xD0)
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_BMP280_REGISTER_RESET = const(0xE0)
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_BMP280_REGISTER_STATUS = const(0xF3)
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_BMP280_REGISTER_CONTROL = const(0xF4)
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_BMP280_REGISTER_CONFIG = const(0xF5) # IIR filter config
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_BMP280_REGISTER_DATA = const(0xF7)
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class BMP280:
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def __init__(self, i2c_bus, addr=0x76, use_case=BMP280_CASE_HANDHELD_DYN):
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self._bmp_i2c = i2c_bus
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self._i2c_addr = addr
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# read calibration data
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# < little-endian
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# H unsigned short
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# h signed short
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self._T1 = unp('<H', self._read(0x88, 2))[0]
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self._T2 = unp('<h', self._read(0x8A, 2))[0]
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self._T3 = unp('<h', self._read(0x8C, 2))[0]
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self._P1 = unp('<H', self._read(0x8E, 2))[0]
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self._P2 = unp('<h', self._read(0x90, 2))[0]
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self._P3 = unp('<h', self._read(0x92, 2))[0]
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self._P4 = unp('<h', self._read(0x94, 2))[0]
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self._P5 = unp('<h', self._read(0x96, 2))[0]
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self._P6 = unp('<h', self._read(0x98, 2))[0]
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self._P7 = unp('<h', self._read(0x9A, 2))[0]
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self._P8 = unp('<h', self._read(0x9C, 2))[0]
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self._P9 = unp('<h', self._read(0x9E, 2))[0]
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# output raw
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self._t_raw = 0
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self._t_fine = 0
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self._t = 0
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self._p_raw = 0
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self._p = 0
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self.read_wait_ms = 0 # interval between forced measure and readout
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self._new_read_ms = 200 # interval between
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self._last_read_ts = 0
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if use_case is not None:
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self.use_case(use_case)
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def _read(self, addr, size=1):
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return self._bmp_i2c.readfrom_mem(self._i2c_addr, addr, size)
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def _write(self, addr, b_arr):
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if not type(b_arr) is bytearray:
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b_arr = bytearray([b_arr])
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return self._bmp_i2c.writeto_mem(self._i2c_addr, addr, b_arr)
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def _gauge(self):
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# TODO limit new reads
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# read all data at once (as by spec)
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d = self._read(_BMP280_REGISTER_DATA, 6)
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self._p_raw = (d[0] << 12) + (d[1] << 4) + (d[2] >> 4)
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self._t_raw = (d[3] << 12) + (d[4] << 4) + (d[5] >> 4)
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self._t_fine = 0
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self._t = 0
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self._p = 0
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def reset(self):
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self._write(_BMP280_REGISTER_RESET, 0xB6)
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def load_test_calibration(self):
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self._T1 = 27504
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self._T2 = 26435
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self._T3 = -1000
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self._P1 = 36477
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self._P2 = -10685
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self._P3 = 3024
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self._P4 = 2855
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self._P5 = 140
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self._P6 = -7
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self._P7 = 15500
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self._P8 = -14600
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self._P9 = 6000
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def load_test_data(self):
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self._t_raw = 519888
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self._p_raw = 415148
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def print_calibration(self):
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print("T1: {} {}".format(self._T1, type(self._T1)))
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print("T2: {} {}".format(self._T2, type(self._T2)))
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print("T3: {} {}".format(self._T3, type(self._T3)))
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print("P1: {} {}".format(self._P1, type(self._P1)))
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print("P2: {} {}".format(self._P2, type(self._P2)))
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print("P3: {} {}".format(self._P3, type(self._P3)))
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print("P4: {} {}".format(self._P4, type(self._P4)))
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print("P5: {} {}".format(self._P5, type(self._P5)))
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print("P6: {} {}".format(self._P6, type(self._P6)))
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print("P7: {} {}".format(self._P7, type(self._P7)))
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print("P8: {} {}".format(self._P8, type(self._P8)))
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print("P9: {} {}".format(self._P9, type(self._P9)))
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def _calc_t_fine(self):
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# From datasheet page 22
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self._gauge()
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if self._t_fine == 0:
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var1 = (((self._t_raw >> 3) - (self._T1 << 1)) * self._T2) >> 11
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var2 = (((((self._t_raw >> 4) - self._T1)
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* ((self._t_raw >> 4)
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- self._T1)) >> 12)
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* self._T3) >> 14
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self._t_fine = var1 + var2
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@property
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def temperature(self):
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self._calc_t_fine()
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if self._t == 0:
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self._t = ((self._t_fine * 5 + 128) >> 8) / 100.
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return self._t
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@property
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def pressure(self):
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# From datasheet page 22
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self._calc_t_fine()
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if self._p == 0:
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var1 = self._t_fine - 128000
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var2 = var1 * var1 * self._P6
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var2 = var2 + ((var1 * self._P5) << 17)
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var2 = var2 + (self._P4 << 35)
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var1 = ((var1 * var1 * self._P3) >> 8) + ((var1 * self._P2) << 12)
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var1 = (((1 << 47) + var1) * self._P1) >> 33
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if var1 == 0:
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return 0
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p = 1048576 - self._p_raw
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p = int((((p << 31) - var2) * 3125) / var1)
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var1 = (self._P9 * (p >> 13) * (p >> 13)) >> 25
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var2 = (self._P8 * p) >> 19
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p = ((p + var1 + var2) >> 8) + (self._P7 << 4)
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self._p = p / 256.0
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return self._p
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def _write_bits(self, address, value, length, shift=0):
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d = self._read(address)[0]
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m = int('1' * length, 2) << shift
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d &= ~m
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d |= m & value << shift
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self._write(address, d)
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def _read_bits(self, address, length, shift=0):
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d = self._read(address)[0]
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return d >> shift & int('1' * length, 2)
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@property
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def standby(self):
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return self._read_bits(_BMP280_REGISTER_CONFIG, 3, 5)
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@standby.setter
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def standby(self, v):
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assert 0 <= v <= 7
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self._write_bits(_BMP280_REGISTER_CONFIG, v, 3, 5)
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@property
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def iir(self):
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return self._read_bits(_BMP280_REGISTER_CONFIG, 3, 2)
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@iir.setter
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def iir(self, v):
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assert 0 <= v <= 4
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self._write_bits(_BMP280_REGISTER_CONFIG, v, 3, 2)
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@property
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def spi3w(self):
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return self._read_bits(_BMP280_REGISTER_CONFIG, 1)
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@spi3w.setter
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def spi3w(self, v):
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assert v in (0, 1)
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self._write_bits(_BMP280_REGISTER_CONFIG, v, 1)
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@property
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def temp_os(self):
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return self._read_bits(_BMP280_REGISTER_CONTROL, 3, 5)
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@temp_os.setter
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def temp_os(self, v):
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assert 0 <= v <= 5
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self._write_bits(_BMP280_REGISTER_CONTROL, v, 3, 5)
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@property
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def press_os(self):
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return self._read_bits(_BMP280_REGISTER_CONTROL, 3, 2)
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@press_os.setter
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def press_os(self, v):
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assert 0 <= v <= 5
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self._write_bits(_BMP280_REGISTER_CONTROL, v, 3, 2)
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@property
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def power_mode(self):
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return self._read_bits(_BMP280_REGISTER_CONTROL, 2)
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@power_mode.setter
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def power_mode(self, v):
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assert 0 <= v <= 3
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self._write_bits(_BMP280_REGISTER_CONTROL, v, 2)
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@property
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def is_measuring(self):
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return bool(self._read_bits(_BMP280_REGISTER_STATUS, 1, 3))
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@property
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def is_updating(self):
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return bool(self._read_bits(_BMP280_REGISTER_STATUS, 1))
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@property
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def chip_id(self):
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return self._read(_BMP280_REGISTER_ID, 2)
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@property
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def in_normal_mode(self):
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return self.power_mode == BMP280_POWER_NORMAL
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def force_measure(self):
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self.power_mode = BMP280_POWER_FORCED
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def normal_measure(self):
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self.power_mode = BMP280_POWER_NORMAL
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def sleep(self):
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self.power_mode = BMP280_POWER_SLEEP
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def use_case(self, uc):
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assert 0 <= uc <= 5
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pm, oss, iir, sb = _BMP280_CASE_MATRIX[uc]
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t_os, p_os, self.read_wait_ms = _BMP280_OS_MATRIX[oss]
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self._write(_BMP280_REGISTER_CONFIG, (iir << 2) + (sb << 5))
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self._write(_BMP280_REGISTER_CONTROL, pm + (p_os << 2) + (t_os << 5))
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def oversample(self, oss):
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assert 0 <= oss <= 4
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t_os, p_os, self.read_wait_ms = _BMP280_OS_MATRIX[oss]
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self._write_bits(_BMP280_REGISTER_CONTROL, p_os + (t_os << 3), 2)
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