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python-bme680/bme680/__init__.py
Phil Howard b4013106dc Added bit setting, docstrings
2017-10-17 11:23:41 +01:00

294 lines
12 KiB
Python
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from .constants import *
import math
import smbus
import time
class BME680(BME680Data):
def __init__(self, i2c_addr=I2C_ADDR_PRIMARY, i2c_device=None):
BME680Data.__init__(self)
self.i2c_addr = i2c_addr
self._i2c = i2c_device
if self._i2c is None:
self._i2c = smbus.SMBus(1)
self.chip_id = self._get_regs(CHIP_ID_ADDR, 1)
if self.chip_id != CHIP_ID:
raise RuntimeError("BME680 Not Found. Invalid CHIP ID: 0x{0:02x}".format(self.chip_id))
self.soft_reset()
self.set_power_mode(SLEEP_MODE)
self._get_calibration_data()
self.set_humidity_oversample(OS_2X)
self.set_pressure_oversample(OS_4X)
self.set_temperature_oversample(OS_8X)
self.set_filter(FILTER_SIZE_3)
self.set_gas_status(ENABLE_GAS_MEAS)
self.get_sensor_data()
def _get_calibration_data(self):
"""Retrieves the sensor calibration data and stores it in .calibration_data"""
calibration = self._get_regs(COEFF_ADDR1, COEFF_ADDR1_LEN)
calibration += self._get_regs(COEFF_ADDR2, COEFF_ADDR2_LEN)
heat_range = self._get_regs(ADDR_RES_HEAT_RANGE_ADDR, 1)
heat_value = twos_comp(self._get_regs(ADDR_RES_HEAT_VAL_ADDR, 1), bits=8)
sw_error = twos_comp(self._get_regs(ADDR_RANGE_SW_ERR_ADDR, 1), bits=8)
self.calibration_data.set_from_array(calibration)
self.calibration_data.set_other(heat_range, heat_value, sw_error)
def soft_reset(self):
"""Initiate a soft reset"""
self._set_regs(SOFT_RESET_ADDR, SOFT_RESET_CMD)
time.sleep(RESET_PERIOD / 1000.0)
def set_humidity_oversample(self, value):
"""Set humidity oversampling"""
self.tph_settings.os_hum = value
self._set_bits(CONF_OS_H_ADDR, OSH_MSK, OSH_POS, value)
#temp = self._get_regs(CONF_OS_H_ADDR, 1)
#temp &= ~OSH_MSK
#temp |= value << OSH_POS
#self._set_regs(CONF_OS_H_ADDR, temp)
def get_humidity_oversample(self):
"""Get humidity oversampling"""
return (self._get_regs(CONF_OS_H_ADDR, 1) & OSH_MSK) >> OSH_POS
def set_pressure_oversample(self, value):
"""Set temperature oversampling"""
self.tph_settings.os_pres = value
self._set_bits(CONF_T_P_MODE_ADDR, OSP_MSK, OSP_POS, value)
#temp = self._get_regs(CONF_T_P_MODE_ADDR, 1)
#temp &= ~OSP_MSK
#temp |= value << OSP_POS
#self._set_regs(CONF_T_P_MODE_ADDR, temp)
def get_pressure_oversample(self):
"""Get pressure oversampling"""
return (self._get_regs(CONF_T_P_MODE_ADDR, 1) & OSP_MSK) >> OSP_POS
def set_temperature_oversample(self, value):
"""Set pressure oversampling"""
self.tph_settings.os_temp = value
self._set_bits(CONF_T_P_MODE_ADDR, OST_MSK, OST_POS, value)
#temp = self._get_regs(CONF_T_P_MODE_ADDR, 1)
#temp &= ~OST_MSK
#temp |= value << OST_POS
#self._set_regs(CONF_T_P_MODE_ADDR, temp)
def get_temperature_oversample(self):
"""Get temperature oversampling"""
return (self._get_regs(CONF_T_P_MODE_ADDR, 1) & OST_MSK) >> OST_POS
def set_filter(self, value):
"""Set filter size"""
self.tph_settings.filter = value
self._set_bits(CONF_ODR_FILT_ADDR, FILTER_MSK, FILTER_POS, value)
#temp = self._get_regs(CONF_ODR_FILT_ADDR, 1)
#temp &= ~FILTER_MSK
#temp |= value << FILTER_POS
#self._set_regs(CONF_ODR_FILT_ADDR, temp)
def get_filter(self):
"""Get filter size"""
return (self._get_regs(CONF_ODR_FILT_ADDR, 1) & FILTER_MSK) >> FILTER_POS
def set_gas_status(self, value):
"""Enable/disable gas sensor"""
self.gas_settings.run_gas = value
self._set_bits(CONF_ODR_RUN_GAS_NBC_ADDR, RUN_GAS_MSK, RUN_GAS_POS, value)
#temp = self._get_regs(CONF_ODR_RUN_GAS_NBC_ADDR, 1)
#temp &= ~RUN_GAS_MSK
#temp |= (value << RUN_GAS_POS)
#self._set_regs(CONF_ODR_RUN_GAS_NBC_ADDR, temp)
def get_gas_status(self):
"""Get the current gas status"""
return (self._get_regs(CONF_ODR_RUN_GAS_NBC_ADDR, 1) & RUN_GAS_MSK) >> RUN_GAS_POS
def set_gas_heater_temperature(self, value):
"""Set gas sensor heater temperature"""
self.gas_settings.heatr_temp = value
temp = self._calc_heater_resistance(self.gas_settings.heatr_temp)
self._set_regs(RES_HEAT0_ADDR, temp)
def set_gas_heater_duration(self, value):
"""Set gas sensor heater duration"""
self.gas_settings.heatr_dur = value
temp = self._calc_heater_duration(self.gas_settings.heatr_dur)
self._set_regs(GAS_WAIT0_ADDR, temp)
def set_power_mode(self, value, blocking=True):
"""Set power mode"""
if value not in (SLEEP_MODE, FORCED_MODE):
print("Power mode should be one of SLEEP_MODE or FORCED_MODE")
self.power_mode = value
self._set_bits(CONF_T_P_MODE_ADDR, MODE_MSK, MODE_POS, value)
#temp = self._get_regs(CONF_T_P_MODE_ADDR, 1)
#temp &= ~ MODE_MSK
#temp |= self.power_mode
#self._set_regs(CONF_T_P_MODE_ADDR, temp)
while blocking and self.get_power_mode() != self.power_mode:
time.sleep(POLL_PERIOD_MS / 1000.0)
def get_power_mode(self):
"""Get power mode"""
self.power_mode = self._get_regs(CONF_T_P_MODE_ADDR, 1)
return self.power_mode
def get_sensor_data(self):
"""Get sensor data.
Stores data in .data and returns True upon success.
"""
self.set_power_mode(FORCED_MODE)
tries = 10
for x in range(10):
regs = self._get_regs(FIELD0_ADDR, FIELD_LENGTH)
self.data.status = regs[0] & NEW_DATA_MSK
self.data.gas_index = regs[0] & GAS_INDEX_MSK
self.data.meas_index = regs[1]
adc_pres = (regs[2] << 12) | (regs[3] << 4) | (regs[4] >> 4)
adc_temp = (regs[5] << 12) | (regs[6] << 4) | (regs[7] >> 4)
adc_hum = (regs[8] << 8) | regs[9]
adc_gas_res = (regs[13] << 2) | (regs[14] >> 6)
gas_range = regs[14] & GAS_RANGE_MSK
self.data.status |= regs[14] & GASM_VALID_MSK
self.data.status |= regs[14] & HEAT_STAB_MSK
self.data.heat_stable = (self.data.status & HEAT_STAB_MSK) > 0
if self.data.status & NEW_DATA_MSK:
temperature = self._calc_temperature(adc_temp)
self.data.temperature = temperature / 100.0
self.ambient_temperature = temperature # Saved for heater calc
self.data.pressure = self._calc_pressure(adc_pres) / 1000.0
self.data.humidity = self._calc_humidity(adc_hum) / 1000.0
self.data.gas_resistance = self._calc_gas_resistance(adc_gas_res, gas_range)
return True
else:
time.sleep(POLL_PERIOD_MS / 1000.0)
return False
def _set_bits(self, register, mask, position, value):
"""Mask out and set one or more bits in a register"""
temp = self._get_regs(register, 1)
temp &= ~mask
temp |= value << position
self._set_regs(register, temp)
def _set_regs(self, register, value):
"""Set one or more registers"""
if isinstance(value, int):
self._i2c.write_byte_data(self.i2c_addr, register, value)
else:
self._i2c.write_i2c_block_data(self.i2c_addr, register, value)
def _get_regs(self, register, length):
"""Get one or more registers"""
if length == 1:
return self._i2c.read_byte_data(self.i2c_addr, register)
else:
return self._i2c.read_i2c_block_data(self.i2c_addr, register, length)
def _calc_temperature(self, temperature_adc):
var1 = (temperature_adc / 8) - (self.calibration_data.par_t1 * 2)
var2 = (var1 * self.calibration_data.par_t2) / 2048
var3 = ((var1 / 2) * (var1 / 2)) / 4096
var3 = ((var3) * (self.calibration_data.par_t3 * 16)) / 16384
# Save teperature data for pressure calculations
self.calibration_data.t_fine = (var2 + var3)
calc_temp = (((self.calibration_data.t_fine * 5) + 128) / 256)
return calc_temp
def _calc_pressure(self, pressure_adc):
var1 = (self.calibration_data.t_fine / 2) - 64000
var2 = ((var1 / 4) * (var1 / 4)) / 2048
var2 = (var2 * self.calibration_data.par_p6) / 4
var2 = var2 + ((var1 * self.calibration_data.par_p5) * 2)
var2 = (var2 / 4) + (self.calibration_data.par_p4 * 65536)
var1 = ((var1 / 4) * (var1 / 4)) / 8192
var1 = ((var1 * (self.calibration_data.par_p3 * 32)) / 8) + ((self.calibration_data.par_p2 * var1) / 2)
var1 = var1 / 262144
var1 = ((32768 + var1) * self.calibration_data.par_p1) / 32768
calc_pres = 1048576 - pressure_adc
calc_pres = (calc_pres - (var2 / 4096)) * 3125
calc_pres = (calc_pres / var1) * 2
var1 = (self.calibration_data.par_p9 * (((calc_pres / 8) * (calc_pres / 8)) / 8192)) / 4096
var2 = ((calc_pres / 4) * self.calibration_data.par_p8) / 8192
var3 = ((calc_pres / 256)
* (calc_pres / 256)
* (calc_pres / 256)
* self.calibration_data.par_p10) / 131072
calc_pres = calc_pres + ((var1 + var2 + var3 + (self.calibration_data.par_p7 * 128)) / 16)
return calc_pres
def _calc_humidity(self, humidity_adc):
temp_scaled = ((self.calibration_data.t_fine * 5) + 128) / 256
var1 = (humidity_adc - ((self.calibration_data.par_h1 * 16))) \
- (((temp_scaled * self.calibration_data.par_h3) / (100)) / 2)
var2 = (self.calibration_data.par_h2
* (((temp_scaled * self.calibration_data.par_h4) / (100))
+ (((temp_scaled * ((temp_scaled * self.calibration_data.par_h5) / (100))) / 64)
/ (100)) + (1 * 16384))) / 1024
var3 = var1 * var2
var4 = self.calibration_data.par_h6 * 128
var4 = ((var4) + ((temp_scaled * self.calibration_data.par_h7) / (100))) / 16
var5 = ((var3 / 16384) * (var3 / 16384)) / 1024
var6 = (var4 * var5) / 2
calc_hum = (((var3 + var6) / 1024) * (1000)) / 4096
return min(max(calc_hum,0),100000)
def _calc_gas_resistance(self, gas_res_adc, gas_range):
var1 = ((1340 + (5 * self.calibration_data.range_sw_err)) * (lookupTable1[gas_range])) / 65536
var2 = (((gas_res_adc * 32768) - (16777216)) + var1)
var3 = ((lookupTable2[gas_range] * var1) / 512)
calc_gas_res = ((var3 + (var2 / 2)) / var2)
return calc_gas_res
def _calc_heater_resistance(self, temperature):
temperature = min(max(temperature,200),400)
var1 = ((self.ambient_temperature * self.calibration_data.par_gh3) / 1000) * 256
var2 = (self.calibration_data.par_gh1 + 784) * (((((self.calibration_data.par_gh2 + 154009) * temperature * 5) / 100) + 3276800) / 10)
var3 = var1 + (var2 / 2)
var4 = (var3 / (self.calibration_data.res_heat_range + 4))
var5 = (131 * self.calibration_data.res_heat_val) + 65536
heatr_res_x100 = (((var4 / var5) - 250) * 34)
heatr_res = ((heatr_res_x100 + 50) / 100)
return heatr_res
def _calc_heater_duration(self, duration):
if duration < 0xfc0:
factor = 0
while duration > 0x3f:
duration /= 4
factor += 1
return int(duration + (factor * 64))
return 0xff
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