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boards/default_src/micropython/origin/build/lib/shtc3.py

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+"""
+SHTC3
+
+MicroPython library for the SHTC3(Humidity and Temperature)
+=======================================================
+
+#Preliminary composition       20220224
+#https://github.com/adafruit/Adafruit_CircuitPython_SHTC3.git
+
+dahanzimin From the Mixly Team
+"""
+
+from time import sleep
+from micropython import const
+from struct import unpack_from
+
+_SHTC3_DEFAULT_ADDR = const(0x70)	# SHTC3 I2C Address
+_SHTC3_READID 		= const(0xEFC8)	# Read Out of ID Register
+_SHTC3_SOFTRESET 	= const(0x805D)	# Soft Reset
+_SHTC3_SLEEP 		= const(0xB098)	# Enter sleep mode
+_SHTC3_WAKEUP 		= const(0x3517)	# Wakeup mode
+_SHTC3_CHIP_ID 		= const(0x807)
+_SHTC3_NORMAL_MEAS 	= const(0x7866)
+_SHTC3_LOWPOW_MEAS 	= const(0x609C)
+
+class SHTC3:
+	def __init__(self, i2c_bus, addr = _SHTC3_DEFAULT_ADDR):
+		self._device= i2c_bus
+		self._address = addr
+		self._buffer = bytearray(6)
+		self.low_power = False
+		self.sleeping = False
+		self.reset()
+		if self._get_chip_id() != _SHTC3_CHIP_ID:
+			raise AttributeError("Cannot find a SHTC3")
+		
+	def _write_command(self, command):
+		"""helper function to write a command to the i2c device"""
+		self._buffer[0] = command >> 8
+		self._buffer[1] = command & 0xFF
+		self._device.writeto(self._address,self._buffer[0:2])
+
+	def _get_chip_id(self):  #   readCommand(SHTC3_READID, data, 3);
+		"""Determines the chip id of the sensor"""
+		self._write_command(_SHTC3_READID)
+		sleep(0.001)
+		self._device.readfrom_into(self._address,self._buffer)
+		return unpack_from(">H", self._buffer)[0] & 0x083F
+	
+	def reset(self):
+		"""Perform a soft reset of the sensor, resetting all settings to their power-on defaults"""
+		self.sleeping = False
+		try:
+			self._write_command(_SHTC3_SOFTRESET)
+
+		except RuntimeError as run_err:
+			if run_err.args and run_err.args[0] != "I2C device address was NACK'd":
+				raise run_err
+		sleep(0.001)
+		
+	@property
+	def sleeping(self):
+		"""Determines the sleep state of the sensor"""
+		return self._cached_sleep
+
+	@sleeping.setter
+	def sleeping(self, sleep_enabled):
+		if sleep_enabled:
+			self._write_command(_SHTC3_SLEEP)
+		else:
+			self._write_command(_SHTC3_WAKEUP)
+		sleep(0.001)
+		self._cached_sleep = sleep_enabled
+
+	@property
+	def low_power(self):
+		"""Enables the less accurate low power mode, trading accuracy for power consumption"""
+		return self._low_power
+
+	@low_power.setter
+	def low_power(self, low_power_enabled):
+		self._low_power = low_power_enabled
+	
+	@property
+	def measurements(self):
+		"""both `temperature` and `relative_humidity`, read simultaneously"""
+		self.sleeping = False
+		temperature = None
+		humidity = None
+		if self.low_power:
+			self._write_command(_SHTC3_LOWPOW_MEAS)
+			sleep(0.001)
+		else:
+			self._write_command(_SHTC3_NORMAL_MEAS)
+			sleep(0.013)
+
+		self._device.readfrom_into(self._address,self._buffer)
+
+		temp_data = self._buffer[0:2]
+		temp_crc = self._buffer[2]
+		humidity_data = self._buffer[3:5]
+		humidity_crc = self._buffer[5]
+
+		if temp_crc != self._crc8(temp_data) or humidity_crc != self._crc8(humidity_data):
+			return
+
+		raw_temp = unpack_from(">H", temp_data)[0]
+		raw_temp = ((4375 * raw_temp) >> 14) - 4500
+		temperature = raw_temp / 100.0
+		raw_humidity = unpack_from(">H", humidity_data)[0]
+		raw_humidity = (625 * raw_humidity) >> 12
+		humidity = raw_humidity / 100.0
+
+		self.sleeping = True
+		return (temperature, humidity)
+
+	@staticmethod
+	def _crc8(buffer):
+		"""verify the crc8 checksum"""
+		crc = 0xFF
+		for byte in buffer:
+			crc ^= byte
+			for _ in range(8):
+				if crc & 0x80:
+					crc = (crc << 1) ^ 0x31
+				else:
+					crc = crc << 1
+		return crc & 0xFF  # return the bottom 8 bits
+
+	def humidity(self):
+		return self.measurements[1]
+
+	def temperature(self):
+		return self.measurements[0]