pynq.iop.grove_tmp — Python productivity for Zynq (Pynq) v1.0

# Source code for pynq.iop.grove_tmp

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    __author__      = "Yun Rock Qu"
    __copyright__   = "Copyright 2016, Xilinx"
    __email__       = "pynq_support@xilinx.com"

    from time import sleep
    from math import log
    from pynq.iop import Grove_ADC
    from pynq.iop import PMODA
    from pynq.iop import PMODB
    from pynq.iop import ARDUINO

    class Grove_TMP(Grove_ADC):
        """This class controls the grove temperature sensor.

        This class inherits from the Grove_ADC class. To use this module, grove
        ADC has to be used as a bridge. The temperature sensor uses a thermistor
        to detect the ambient temperature. Hardware version: v1.2.

        Attributes
        ----------
        iop : _IOP
            I/O processor instance used by Grove ADC.
        mmio : MMIO
            Memory-mapped I/O instance to read and write instructions and data.
        log_running : int
            The state of the log (0: stopped, 1: started).
        log_interval_ms : int
            Time in milliseconds between sampled reads of the Grove ADC sensor.
        bValue : int
            The thermistor constant.

        """
        def __init__(self, if_id, gr_pin, version='v1.2'):
            """Return a new instance of a Grove_TMP object.

            Note
            ----
            The parameter `gr_pin` is a list organized as [scl_pin, sda_pin].

            Parameters
            ----------
            if_id : int
                The interface ID (1,2,3) corresponding to (PMODA,PMODB,arduino).
            gr_pin: list
                A group of pins on stickit connector or arduino shield.
            version : str
                The hardware version number (can be found on device).

            """
            if not if_id in [PMODA, PMODB, ARDUINO]:
                raise ValueError("No such IOP for grove device.")

            if version == 'v1.2':
                # v1.2 uses NCP18WF104F03RC
                self.bValue = 4250
            elif version == 'v1.1':
                # v1.1 uses thermistor NCP18WF104F03RC
                self.bValue = 4250
            else:
                # v1.0 uses thermistor TTC3A103*39H
                self.bValue = 3975

            super().__init__(if_id, gr_pin)

        def read(self):
            """Read temperature values in Celsius from temperature sensor.

            This method overrides the definition in Grove_ADC.

            Parameters
            ----------
            None

            Returns
            -------
            float
                The temperature reading in Celsius.

            """
            # Transform the ADC data into degree Celsius
            val = super().read_raw()
            return self._int2temp(val)

        def start_log(self):
            """Start recording temperature in a log.

            This method will call the start_log_raw() in the parent class.

            Parameters
            ----------
            None

            Returns
            -------
            None

            """
            super().start_log_raw()

        def get_log(self):
            """Return list of logged temperature samples.

            Parameters
            ----------
            None

            Returns
            -------
            list
                List of valid temperature readings from the temperature sensor.

            """
            # Stop and get the log
            tmp_log = super().get_log_raw()

            for i in range(len(tmp_log)):
                tmp_log[i] = self._int2temp(tmp_log[i])
            return tmp_log

        def stop_log(self):
            """Stop recording temperature in a log.

            This method will call the stop_log_raw() in the parent class.

            Parameters
            ----------
            None

            Returns
            -------
            None

            """
            super().stop_log_raw()

        def _int2temp(self, val):
            """Convert the integer value to temperature in Celsius.

            This method should only be used internally.

            Parameters
            ----------
            val : int
                The raw data read from grove ADC.

            Returns
            -------
            float
                The temperature reading in Celsius.

            """
            R = 4095.0/val - 1.0
            temp = 1.0/(log(R)/self.bValue + 1/298.15)-273.15
            return float("{0:.2f}".format(temp))