pynq.board.led — Python productivity for Zynq (Pynq) v1.0

# Source code for pynq.board.led

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    __author__ = "Giuseppe Natale"
    __copyright__ = "Copyright 2016, Xilinx"
    __email__ = "pynq_support@xilinx.com"

    from pynq import MMIO
    from pynq import PL

    LEDS_OFFSET0 = 0x8
    LEDS_OFFSET1 = 0xC

    class LED(object):
        """This class controls the onboard LEDs.

        Attributes
        ----------
        index : int
            The index of the onboard LED, starting from 0.
        """
        _mmio = None
        _leds_value = 0

        def __init__(self, index):
            """Create a new LED object.

            Parameters
            ----------
            index : int
                Index of the LED, from 0 to 3.

            """
            if not index in range(4):
                raise Value("Index for onboard LEDs should be 0 - 3.")

            self.index = index
            if LED._mmio is None:
                LED._mmio = MMIO(int(PL.ip_dict["SEG_swsleds_gpio_Reg"][0],16),16)
            LED._mmio.write(LEDS_OFFSET1, 0x0)

        def toggle(self):
            """Flip the state of a single LED.

            If the LED is on, it will be turned off. If the LED is off, it will be
            turned on.

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

            Returns
            -------
            None

            """
            new_val = (LED._leds_value) ^ (0x1 << self.index)
            self._set_leds_value(new_val)

        def on(self):
            """Turn on a single LED.

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

            Returns
            -------
            None

            """
            new_val = (LED._leds_value) | (0x1 << self.index)
            self._set_leds_value(new_val)

        def off(self):
            """Turn off a single LED.

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

            Returns
            -------
            None

            """
            new_val = (LED._leds_value) & (0xff ^ (0x1 << self.index))
            self._set_leds_value(new_val)

        def write(self, value):
            """Set the LED state according to the input value.

            Parameters
            ----------
            value : int
                This parameter can be either 0 (off) or 1 (on).

            Raises
            ------
            ValueError
                If the value parameter is not 0 or 1.

            """
            if (value not in (0, 1)):
                raise ValueError("Value should be 0 or 1.")
            if value:
                self.on()
            else:
                self.off()

        def read(self):
            """Retrieve the LED state.

            Returns
            -------
            int
                Either 0 if the LED is off or 1 if the LED is on.

            """
            return (LED._leds_value >> self.index) & 0x1

        def _set_leds_value(self, value):
            """Set the state of all LEDs.

            Note
            ----
            This function should not be used directly. User should rely
            on `toggle()`, `on()`, `off()`, `write()`, and `read()` instead

            Parameters
            ----------
            value : int
                The value of all the LEDs encoded in a single variable

            """
            LED._leds_value = value
            LED._mmio.write(LEDS_OFFSET0, value)