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

# Source code for pynq.iop.pmod_timer

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    __author__      = "Parimal Patel"
    __copyright__   = "Copyright 2016, Xilinx"
    __email__       = "pynq_support@xilinx.com"

    import time
    import struct
    from pynq import MMIO
    from pynq.iop import request_iop
    from pynq.iop import iop_const
    from pynq.iop import PMODA
    from pynq.iop import PMODB

    PMOD_TIMER_PROGRAM = "pmod_timer.bin"

    class Pmod_Timer(object):
        """This class uses the timer's capture and generation capabilities.

        Attributes
        ----------
        iop : _IOP
            I/O processor instance used by Pmod_Timer.
        mmio : MMIO
            Memory-mapped I/O instance to read and write instructions and data.
        clk : int
            The clock period of the IOP in ns.

        """
        def __init__(self, if_id, index):
            """Return a new instance of an Pmod_Timer object.

            Parameters
            ----------
            if_id : int
                The interface ID (1, 2) corresponding to (PMODA, PMODB).
            index : int
                The specific pin that runs timer.

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

            self.iop = request_iop(if_id, PMOD_TIMER_PROGRAM)
            self.mmio = self.iop.mmio
            self.clk = int(pow(10,9)/iop_const.IOP_FREQUENCY)
            self.iop.start()

            # Write PWM pin config
            self.mmio.write(iop_const.MAILBOX_OFFSET, index)

            # Write configuration and wait for ACK
            self.mmio.write(iop_const.MAILBOX_OFFSET + \
                            iop_const.MAILBOX_PY2IOP_CMD_OFFSET, 0x1)
            while not (self.mmio.read(iop_const.MAILBOX_OFFSET + \
                                      iop_const.MAILBOX_PY2IOP_CMD_OFFSET) == 0):
                pass

        def stop(self):
            """This method stops the timer.

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

            Returns
            -------
            None

            """
            self.mmio.write(iop_const.MAILBOX_OFFSET+\
                            iop_const.MAILBOX_PY2IOP_CMD_OFFSET, 0x3)
            while not (self.mmio.read(iop_const.MAILBOX_OFFSET+\
                                      iop_const.MAILBOX_PY2IOP_CMD_OFFSET) == 0):
                pass

        def generate_pulse(self, period, times=0):
            """Generate pulses every (period+2) clocks for a number of times.

            The default is to generate pulses every (period+2) IOP clocks forever
            until stopped. The pulse width is equal to the IOP clock period.

            Parameters
            ----------
            period : int
                A parameter related to the period of the generated signals.
            times : int
                The number of times for which the pulses are generated.

            Returns
            -------
            None

            """
            if times == 0:
                # Generate pulses forever
                if (period not in range(1,4294967294)):
                    raise ValueError("Valid period is between 1 and 4294967294.")

                self.mmio.write(iop_const.MAILBOX_OFFSET, period)
                self.mmio.write(iop_const.MAILBOX_OFFSET+\
                                iop_const.MAILBOX_PY2IOP_CMD_OFFSET, 0x5)
                while not (self.mmio.read(iop_const.MAILBOX_OFFSET+\
                                    iop_const.MAILBOX_PY2IOP_CMD_OFFSET) == 0):
                    pass

            elif 1 <= times < 255:
                # Generate pulses for a certain times
                if (period not in range(1,16777215)):
                    raise ValueError("Valid period is between 1 and 16777215.")

                self.mmio.write(iop_const.MAILBOX_OFFSET, (period << 8) | times)
                self.mmio.write(iop_const.MAILBOX_OFFSET+\
                                iop_const.MAILBOX_PY2IOP_CMD_OFFSET, 0x7)
                while not (self.mmio.read(iop_const.MAILBOX_OFFSET+\
                                    iop_const.MAILBOX_PY2IOP_CMD_OFFSET) == 0):
                    pass

            else:
                raise ValueError("Valid number of times is between 1 and 255.")

        def event_detected(self, period):
            """Detect a rising edge or high-level in (period+2) clocks.

            Parameters
            ----------
            period : int
                A parameter related to the period of the generated signals.

            Returns
            -------
            int
                1 if any event is detected, and 0 if no event is detected.

            """
            if (period not in range(50,4294967294)):
                raise ValueError("Valid period is between 50 and 4294967294.")

            self.mmio.write(iop_const.MAILBOX_OFFSET, period)
            self.mmio.write(iop_const.MAILBOX_OFFSET+\
                            iop_const.MAILBOX_PY2IOP_CMD_OFFSET, 0x9)
            while not (self.mmio.read(iop_const.MAILBOX_OFFSET+\
                                      iop_const.MAILBOX_PY2IOP_CMD_OFFSET) == 0):
                pass
            return self.mmio.read(iop_const.MAILBOX_OFFSET)

        def event_count(self, period):
            """Count the number of rising edges detected in (period+2) clocks.

            Parameters
            ----------
            period : int
                A parameter related to the period of the generated signals.

            Returns
            -------
            int
                The number of events detected.

            """
            if (period not in range(50,4294967295)):
                raise ValueError("Valid period is between 50 and 4294967295.")

            self.mmio.write(iop_const.MAILBOX_OFFSET, period)
            self.mmio.write(iop_const.MAILBOX_OFFSET+\
                            iop_const.MAILBOX_PY2IOP_CMD_OFFSET, 0xB)
            while not (self.mmio.read(iop_const.MAILBOX_OFFSET+\
                                      iop_const.MAILBOX_PY2IOP_CMD_OFFSET) == 0):
                pass
            return self.mmio.read(iop_const.MAILBOX_OFFSET)

        def get_period_ns(self):
            """Measure the period between two successive rising edges.

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

            Returns
            -------
            int
                Measured period in ns.

            """
            self.mmio.write(iop_const.MAILBOX_OFFSET+\
                            iop_const.MAILBOX_PY2IOP_CMD_OFFSET, 0xD)
            while not (self.mmio.read(iop_const.MAILBOX_OFFSET+\
                                      iop_const.MAILBOX_PY2IOP_CMD_OFFSET) == 0):
                pass
            return self.mmio.read(iop_const.MAILBOX_OFFSET) * self.clk