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

# Source code for pynq.iop.pmod_pwm

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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_PWM_PROGRAM = "pmod_pwm.bin"

    class Pmod_PWM(object):
        """This class uses the PWM of the IOP.

        Attributes
        ----------
        iop : _IOP
            I/O processor instance used by Pmod_PWM.
        mmio : MMIO
            Memory-mapped I/O instance to read and write instructions and data.

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

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

            """
            if not if_id in [PMODA, PMODB]:
                raise ValueError("No such IOP for Pmod device.")
            if not index in range(8):
                raise ValueError("Valid pin indexes are 0 - 7.")

            self.iop = request_iop(if_id, PMOD_PWM_PROGRAM)
            self.mmio = self.iop.mmio
            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 generate(self,period,duty_cycle):
            """Generate pwm signal with desired period and percent duty cycle.

            Parameters
            ----------
            period : int
                The period of the tone (us), between 1 and 65536.
            duty_cycle : int
                The duty cycle in percentage.

            Returns
            -------
            None

            """
            if (period not in range(1,65536)):
                raise ValueError("Valid tone period is between 1 and 65536.")
            if (duty_cycle not in range(1,99)):
                raise ValueError("Valid duty cycle is between 1 and 99.")

            self.mmio.write(iop_const.MAILBOX_OFFSET, period)
            self.mmio.write(iop_const.MAILBOX_OFFSET+0x4, duty_cycle)
            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 stop(self):
            """Stops PWM generation.

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

            Returns
            -------
            None

            """
            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