Source code for sensirion_i2c_stc.stc3x.commands

# -*- coding: utf-8 -*-
# (c) Copyright 2021 Sensirion AG, Switzerland

# flake8: noqa

from __future__ import absolute_import, division, print_function

import logging
from struct import pack, unpack

from sensirion_i2c_driver import SensirionI2cCommand, CrcCalculator

from sensirion_i2c_stc.stc3x.data_types import \
    Stc3xRelativeHumidityConditionPercent, Stc3xTemperatureConditionDegC, \
    Stc3xReferenceConcentration
from sensirion_i2c_stc.stc3x.response_types import Stc3xTemperature, \
    Stc3xGasConcentration

log = logging.getLogger(__name__)


[docs]class Stc3xI2cCmdBase(SensirionI2cCommand): """ STC3x I²C base command. """
[docs] def __init__(self, command, tx_data, rx_length, read_delay, timeout, post_processing_time=0.0): """ Constructs a new STC3x I²C command. :param int/None command: The command ID to be sent to the device. None means that no command will be sent, i.e. only ``tx_data`` (if not None) will be sent. No CRC is added to these bytes since the command ID usually already contains a CRC. :param bytes-like/list/None tx_data: Bytes to be extended with CRCs and then sent to the I²C device. None means that no write header will be sent at all (if ``command`` is None too). An empty list means to send the write header (even if ``command`` is None), but without data following it. :param int/None rx_length: Number of bytes to be read from the I²C device, including CRC bytes. None means that no read header is sent at all. Zero means to send the read header, but without reading any data. :param float read_delay: Delay (in Seconds) to be inserted between the end of the write operation and the beginning of the read operation. This is needed if the device needs some time to prepare the RX data, e.g. if it has to perform a measurement. Set to 0.0 to indicate that no delay is needed, i.e. the device does not need any processing time. :param float timeout: Timeout (in Seconds) to be used in case of clock stretching. If the device stretches the clock longer than this value, the transceive operation will be aborted with a timeout error. Set to 0.0 to indicate that the device will not stretch the clock for this command. :param float post_processing_time: Maximum time in seconds the device needs for post processing of this command until it is ready to receive the next command. For example after a device reset command, the device might need some time until it is ready again. Usually this is 0.0s, i.e. no post processing is needed. """ super(Stc3xI2cCmdBase, self).__init__( command=command, tx_data=tx_data, rx_length=rx_length, read_delay=read_delay, timeout=timeout, crc=CrcCalculator(8, 0x31, 0xFF, 0x00), command_bytes=2, post_processing_time=post_processing_time, )
[docs]class Stc3xI2cCmdSetBinaryGas(Stc3xI2cCmdBase): """ Set Binary Gas I²C Command The STC3x measures the concentration of binary gas mixtures. It is important to note that the STC3x is not selective for gases, and it assumes that the binary gas is set correctly. The sensor can only give a correct concentration value when only the gases set with this command are present. When the system is reset, or wakes up from sleep mode, the sensor goes back to default mode, in which no binary gas is selected. This means that the binary gas must be reconfigured. When no binary gas is selected (default mode) the concentration measurement will return undefined results. This allows to detect unexpected sensor interruption (e.g. due to temporary power loss) and consequently reset the binary gas to the appropriate mixture. """
[docs] def __init__(self, binary_gas): """ Constructor. :param int binary_gas: See section 3.3.2 in the corresponding datasheet for a list of available binary gases. See :py:class:`Stc31BinaryGas` """ super(Stc3xI2cCmdSetBinaryGas, self).__init__( command=0x3615, tx_data=b"".join([pack(">H", binary_gas)]), rx_length=None, read_delay=0.0, timeout=0, post_processing_time=0.001, )
[docs]class Stc3xI2cCmdSetRelativeHumidity(Stc3xI2cCmdBase): """ Set Relative Humidity I²C Command As mentioned in section 5.1 of the datasheet, the measurement principle of the concentration measurement is dependent on the humidity of the gas. With the set relative humidity command, the sensor uses internal algorithms to compensate the concentration results. When no value is written to the sensor after a soft reset, wake-up or power-up, a relative humidity of 0% is assumed. The value written to the sensor is used until a new value is written to the sensor """
[docs] def __init__(self, relative_humidity_percent): """ Constructor. :param float relative_humidity_percent: Relative humidity conditions. """ super(Stc3xI2cCmdSetRelativeHumidity, self).__init__( command=0x3624, tx_data=b"".join([pack(">H", Stc3xRelativeHumidityConditionPercent( relative_humidity_percent).ticks)]), rx_length=None, read_delay=0.0, timeout=0, post_processing_time=0.001, )
[docs]class Stc3xI2cCmdSetTemperature(Stc3xI2cCmdBase): """ Set Temperature I²C Command The concentration measurement requires a compensation of temperature. Per default, the sensor uses the internal temperature sensor to compensate the concentration results. However, when using the SHTxx, it is recommended to also use its temperature value, because it is more accurate. When no value is written to the sensor after a soft reset, wake-up or power-up, the internal temperature signal is used. The value written to the sensor is used until a new value is written to the sensor. """
[docs] def __init__(self, temperature_degree_celsius): """ Constructor. :param float temperature_degree_celsius: Temperature conditions. """ super(Stc3xI2cCmdSetTemperature, self).__init__( command=0x361E, tx_data=b"".join([pack(">H", Stc3xTemperatureConditionDegC( temperature_degree_celsius).ticks)]), rx_length=None, read_delay=0.0, timeout=0, post_processing_time=0.001, )
[docs]class Stc3xI2cCmdSetPressure(Stc3xI2cCmdBase): """ Set Pressure I²C Command A pressure value can be written into the sensor, for density compensation of the gas concentration measurement. It is recommended to set the pressure level, if it differs significantly from 1013mbar. Pressure compensation is valid from 600mbar to 1200mbar. When no value is written to the sensor after a soft reset, wake-up or power-up, a pressure of 1013mbar is assumed. The value written is used until a new value is written to the sensor. """
[docs] def __init__(self, absolue_pressure): """ Constructor. :param int absolue_pressure: Ambient pressure in mbar (milli-bars) """ super(Stc3xI2cCmdSetPressure, self).__init__( command=0x362F, tx_data=b"".join([pack(">H", int(absolue_pressure))]), rx_length=None, read_delay=0.0, timeout=0, post_processing_time=0.001, )
[docs]class Stc3xI2cCmdMeasureGasConcentration(Stc3xI2cCmdBase): """ Measure Gas Concentration I²C Command The measurement of gas concentration is done in one measurement in a single shot, and takes less than 66ms. When measurement data is available, it can be read out by sending an I2C read header and reading out the data from the sensor. If no measurement data is available yet, the sensor will respond with a NACK on the I2C read header. In case the ‘Set temperature command’ has been used prior to the measurement command, the temperature value given out by the STC3x will be that one of the ‘Set temperature command’. When the ‘Set temperature command’ has not been used, the internal temperature value can be read out. During product development it is recommended to compare the internal temperature value of the STC3x and the temperature value of the SHTxx, to check whether both sensors are properly thermally coupled. The values must be within 0.7°C. .. note:: The Gas concentration is a 16-bit unsigned integer. The temperature and byte 7 and 8 don’t need to be read out. The read sequence can be aborted after any byte by a NACK and a STOP condition. The measurement command should not be triggered more often than once a second. """
[docs] def __init__(self): """ Constructor. """ super(Stc3xI2cCmdMeasureGasConcentration, self).__init__( command=0x3639, tx_data=None, rx_length=6, read_delay=0.07, timeout=0, post_processing_time=0.0, )
[docs] def interpret_response(self, data): """ Validates the CRCs of the received data from the device and returns the interpreted data. :param bytes data: Received raw bytes from the read operation. :return: - gas_concentration (:py:class:sensirion_i2c_stc.stc3x.response_types.Stc3xGasConcentration) Gas concentration response object - temperature (:py:class:sensirion_i2c_stc.stc3x.reasponse_types.Stc3xTemperature) Temperature response object. :rtype: tuple :raise ~sensirion_i2c_driver.errors.I2cChecksumError: If a received CRC was wrong. """ # check and remove CRCs checked_data = Stc3xI2cCmdBase.interpret_response(self, data) # convert raw received data into proper data types gas_ticks = int(unpack(">H", checked_data[0:2])[0]) # uint16 temperature_ticks = int(unpack(">H", checked_data[2:4])[0]) # uint16 return Stc3xGasConcentration(gas_ticks), Stc3xTemperature( temperature_ticks)
[docs]class Stc3xI2cCmdForcedRecalibration(Stc3xI2cCmdBase): """ Forced Recalibration I²C Command Forced recalibration (FRC) is used to improve the sensor output with a known reference value. See the Field Calibration Guide for more details. If no argument is given, the sensor will assume a default value of 0 vol%. This command will trigger a concentration measurement as described in 3.3.6 of the datasheet and therefore it will take the same measurement time. """
[docs] def __init__(self, reference_concentration_vol_percent): """ Constructor. :param int reference_concentration_vol_percent: Reference concentration """ super(Stc3xI2cCmdForcedRecalibration, self).__init__( command=0x3661, tx_data=b"".join([pack(">H", Stc3xReferenceConcentration( reference_concentration_vol_percent).ticks)]), rx_length=None, read_delay=0.0, timeout=0, post_processing_time=0.066, )
[docs]class Stc3xI2cCmdEnableAutomaticSelfCalibration(Stc3xI2cCmdBase): """ Enable Automatic Self Calibration I²C Command Enable the automatic self-calibration (ASC). The sensor can run in automatic self-calibration mode. This mode will enhance the accuracy for applications where the target gas is not present for the majority of the time. See the Field Calibration Guide for more details. This feature can be enabled or disabled by using the commands as shown below. The automatic self-calibration is optimized for a gas concentration measurement interval of 1s. Substantially different measurement intervals may decrease the self-calibration performance. The default state is disabled. Automatic self-calibration in combination with sleep mode requires a specific sequence of steps. See section 3.3.9 in the datasheet for more detailed instructions .. note:: The sensor will apply automatic self-calibration """
[docs] def __init__(self): """ Constructor. """ super(Stc3xI2cCmdEnableAutomaticSelfCalibration, self).__init__( command=0x3FEF, tx_data=None, rx_length=None, read_delay=0.0, timeout=0, post_processing_time=0.001, )
[docs]class Stc3xI2cCmdDisableAutomaticSelfCalibration(Stc3xI2cCmdBase): """ Disable Automatic Self Calibration I²C Command Disable the automatic self-calibration (ASC). The sensor can run in automatic self-calibration mode. This mode will enhance the accuracy for applications where the target gas is not present for the majority of the time. See the Field Calibration Guide for more details. This feature can be enabled or disabled by using the commands as shown below. The default state is disabled. .. note:: The sensor will not apply automatic self-calibration. This is the default state of the sensor. """
[docs] def __init__(self): """ Constructor. """ super(Stc3xI2cCmdDisableAutomaticSelfCalibration, self).__init__( command=0x3F6E, tx_data=None, rx_length=None, read_delay=0.0, timeout=0, post_processing_time=0.001, )
[docs]class Stc3xI2cCmdPrepareReadState(Stc3xI2cCmdBase): """ Prepare Read State I²C Command The sensor will prepare its current state to be read out. .. note:: See section 3.3.9 of the datasheet for detailed instructions. """
[docs] def __init__(self): """ Constructor. """ super(Stc3xI2cCmdPrepareReadState, self).__init__( command=0x3752, tx_data=None, rx_length=None, read_delay=0.0, timeout=0, post_processing_time=0.001, )
[docs]class Stc3xI2cCmdGetSensorState(Stc3xI2cCmdBase): """ Get Sensor State I²C Command Read out the sensor state. """
[docs] def __init__(self): """ Constructor. """ super(Stc3xI2cCmdGetSensorState, self).__init__( command=0xE133, tx_data=None, rx_length=45, read_delay=0.0, timeout=0, post_processing_time=0.0, )
[docs] def interpret_response(self, data): """ Validates the CRCs of the received data from the device and returns the interpreted data. :param bytes data: Received raw bytes from the read operation. :return: Current sensor state :rtype: list(int) :raise ~sensirion_i2c_driver.errors.I2cChecksumError: If a received CRC was wrong. """ # check and remove CRCs checked_data = Stc3xI2cCmdBase.interpret_response(self, data) # convert raw received data into proper data types state = [int(ii) for ii in unpack(">{}B".format(len(checked_data[0:30]) // 1), checked_data[0:30])] # list(uint8) return state
[docs]class Stc3xI2cCmdSetSensorState(Stc3xI2cCmdBase): """ Set Sensor State I²C Command Write the sensor state as read out earlier. """
[docs] def __init__(self, state): """ Constructor. :param list(int) state: Current sensor state """ super(Stc3xI2cCmdSetSensorState, self).__init__( command=0xE133, tx_data=b"".join([pack(">{}B".format(len(state)), *state)]), rx_length=None, read_delay=0.0, timeout=0, post_processing_time=0.0, )
[docs]class Stc3xI2cCmdApplyState(Stc3xI2cCmdBase): """ Apply State I²C Command The sensor will apply the written state data. .. note:: See section 3.3.9 of the datasheet for detailed instructions. """
[docs] def __init__(self): """ Constructor. """ super(Stc3xI2cCmdApplyState, self).__init__( command=0x3650, tx_data=None, rx_length=None, read_delay=0.0, timeout=0, post_processing_time=0.001, )
[docs]class Stc3xI2cCmdSelfTest(Stc3xI2cCmdBase): """ Self Test I²C Command The sensor will run an on-chip self-test. A successful self-test will return zero. The 16-bit result of a sensor self-test is a combination of possible error states, encoded as bits (starting with lsb). """
[docs] def __init__(self): """ Constructor. """ super(Stc3xI2cCmdSelfTest, self).__init__( command=0x365B, tx_data=None, rx_length=3, read_delay=0.022, timeout=0, post_processing_time=0.0, )
[docs] def interpret_response(self, data): """ Validates the CRCs of the received data from the device and returns the interpreted data. :param bytes data: Received raw bytes from the read operation. :return: Self test result. Error code or 0x0000 on success. :rtype: int :raise ~sensirion_i2c_driver.errors.I2cChecksumError: If a received CRC was wrong. """ # check and remove CRCs checked_data = Stc3xI2cCmdBase.interpret_response(self, data) # convert raw received data into proper data types self_test_output = int(unpack(">H", checked_data[0:2])[0]) # uint16 return self_test_output
[docs]class Stc3xI2cCmdEnterSleepMode(Stc3xI2cCmdBase): """ Enter Sleep Mode I²C Command Put sensor into sleep mode. In sleep mode the sensor uses the minimum amount of current. The mode can only be entered from idle mode, i.e. when the sensor is not measuring. This mode is particularly useful for battery operated devices. To minimize the current in this mode, the complexity of the sleep mode circuit has been reduced as much as possible, which is mainly reflected by the way the sensor exits the sleep mode. The sleep command can be sent after the result have been read out and the sensor is in idle mode. The sensor exits the sleep mode and enters the idle mode when it receives the valid I2C address and a write bit (‘0’). Note that the I2C address is not acknowledged. It is possible to poll the sensor to see whether the sensor has received the address and has woken up. This takes maximum 12ms. .. note:: Only available in idle mode """
[docs] def __init__(self): """ Constructor. """ super(Stc3xI2cCmdEnterSleepMode, self).__init__( command=0x3677, tx_data=None, rx_length=None, read_delay=0.0, timeout=0, post_processing_time=0.001, )
[docs]class Stc3xI2cCmdPrepareProductIdentifier(Stc3xI2cCmdBase): """ Prepare Product Identifier I²C Command Prepare for reading the product identifier and sensor serial number. """
[docs] def __init__(self): """ Constructor. """ super(Stc3xI2cCmdPrepareProductIdentifier, self).__init__( command=0x367C, tx_data=None, rx_length=None, read_delay=0.0, timeout=0, post_processing_time=0.0, )
[docs]class Stc3xI2cCmdReadProductIdentifier(Stc3xI2cCmdBase): """ Read Product Identifier I²C Command Read the product identifier and sensor serial number. .. note:: Make sure to call 'prepare product identifier' immediately before. """
[docs] def __init__(self): """ Constructor. """ super(Stc3xI2cCmdReadProductIdentifier, self).__init__( command=0xE102, tx_data=None, rx_length=18, read_delay=0.01, timeout=0, post_processing_time=0.0, )
[docs] def interpret_response(self, data): """ Validates the CRCs of the received data from the device and returns the interpreted data. :param bytes data: Received raw bytes from the read operation. :return: - product_number (int) - 32-bit unique product and revision number. The number is listed below: STC31: 0x08010301 - serial_number (unsigned long long) 64-bit unique serial number :rtype: tuple :raise ~sensirion_i2c_driver.errors.I2cChecksumError: If a received CRC was wrong. """ # check and remove CRCs checked_data = Stc3xI2cCmdBase.interpret_response(self, data) # convert raw received data into proper data types product_number = int(unpack(">I", checked_data[0:4])[0]) # uint32 serial_number = int(unpack(">Q", checked_data[4:12])[0]) # uint64 return product_number, serial_number