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

# Source code for pynq.iop.grove_adc

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    __author__      = "Cathal McCabe"
    __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
    from pynq.iop import ARDUINO
    from pynq.iop import PMOD_GROVE_G3
    from pynq.iop import PMOD_GROVE_G4
    from pynq.iop import ARDUINO_GROVE_I2C

    PMOD_GROVE_ADC_PROGRAM = "pmod_grove_adc.bin"
    ARDUINO_GROVE_ADC_PROGRAM = "arduino_grove_adc.bin"
    GROVE_ADC_LOG_START = iop_const.MAILBOX_OFFSET+16
    GROVE_ADC_LOG_END = GROVE_ADC_LOG_START+(1000*4)

    class Grove_ADC(object):
        """This class controls the Grove IIC ADC.

        Grove ADC is a 12-bit precision ADC module based on ADC121C021. 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.

        """
        def __init__(self, if_id, gr_pin):
            """Return a new instance of an Grove_ADC 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.

            """
            if if_id in [PMODA, PMODB]:
                if not gr_pin in [PMOD_GROVE_G3, \
                                  PMOD_GROVE_G4]:
                    raise ValueError("ADC group number can only be G3 - G4.")
                GROVE_ADC_PROGRAM = PMOD_GROVE_ADC_PROGRAM
            elif if_id in [ARDUINO]:
                if not gr_pin in [ARDUINO_GROVE_I2C]:
                    raise ValueError("ADC group number can only be I2C.")
                GROVE_ADC_PROGRAM = ARDUINO_GROVE_ADC_PROGRAM
            else:
                raise ValueError("No such IOP for grove device.")

            self.iop = request_iop(if_id, GROVE_ADC_PROGRAM)
            self.mmio = self.iop.mmio
            self.log_interval_ms = 1000
            self.log_running  = 0
            self.iop.start()

            if if_id in [PMODA, PMODB]:
                # Write SCL and SDA pin config
                self.mmio.write(iop_const.MAILBOX_OFFSET, gr_pin[0])
                self.mmio.write(iop_const.MAILBOX_OFFSET+4, gr_pin[1])

                # Write configuration and wait for ACK
                self.mmio.write(iop_const.MAILBOX_OFFSET + \
                                iop_const.MAILBOX_PY2IOP_CMD_OFFSET, 1)
                while (self.mmio.read(iop_const.MAILBOX_OFFSET + \
                                      iop_const.MAILBOX_PY2IOP_CMD_OFFSET) == 1):
                    pass

        def read_raw(self):
            """Read the ADC raw value from the Grove ADC peripheral.

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

            Returns
            -------
            int
                The raw value from the sensor.

            """
            self.mmio.write(iop_const.MAILBOX_OFFSET+ \
                            iop_const.MAILBOX_PY2IOP_CMD_OFFSET, 2)
            while (self.mmio.read(iop_const.MAILBOX_OFFSET + \
                                    iop_const.MAILBOX_PY2IOP_CMD_OFFSET) == 2):
                pass
            value = self.mmio.read(iop_const.MAILBOX_OFFSET)
            return value

        def read(self):
            """Read the ADC voltage from the Grove ADC peripheral.

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

            Returns
            -------
            float
                The float value after translation.

            """
            self.mmio.write(iop_const.MAILBOX_OFFSET + \
                            iop_const.MAILBOX_PY2IOP_CMD_OFFSET, 3)
            while (self.mmio.read(iop_const.MAILBOX_OFFSET + \
                                    iop_const.MAILBOX_PY2IOP_CMD_OFFSET) == 3):
                pass
            value = self.mmio.read(iop_const.MAILBOX_OFFSET)
            return self._reg2float(value)

        def set_log_interval_ms(self, log_interval_ms):
            """Set the length of the log for the Grove_ADC peripheral.

            This method can set the time interval between two samples, so that
            users can read out multiple values in a single log.

            Parameters
            ----------
            log_interval_ms : int
                The time between two samples in milliseconds, for logging only.

            Returns
            -------
            None

            """
            if (log_interval_ms < 0):
                raise ValueError("Time between samples should be no less than 0.")

            self.log_interval_ms = log_interval_ms
            self.mmio.write(iop_const.MAILBOX_OFFSET+4, self.log_interval_ms)

        def start_log_raw(self):
            """Start recording raw data in a log.

            This method will first call set_log_interval_ms() before writting to
            the MMIO.

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

            Returns
            -------
            None

            """
            self.log_running = 1
            self.set_log_interval_ms(self.log_interval_ms)
            self.mmio.write(iop_const.MAILBOX_OFFSET + \
                            iop_const.MAILBOX_PY2IOP_CMD_OFFSET, 4)

        def start_log(self):
            """Start recording multiple voltage values (float) in a log.

            This method will first call set_log_interval_ms() before writting to
            the MMIO.

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

            Returns
            -------
            None

            """
            self.log_running = 1
            self.set_log_interval_ms(self.log_interval_ms)
            self.mmio.write(iop_const.MAILBOX_OFFSET + \
                            iop_const.MAILBOX_PY2IOP_CMD_OFFSET, 5)

        def stop_log_raw(self):
            """Stop recording the raw values in the log.

            Simply write 0xC to the MMIO to stop the log.

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

            Returns
            -------
            None

            """
            if(self.log_running == 1):
                self.mmio.write(iop_const.MAILBOX_OFFSET+ \
                            iop_const.MAILBOX_PY2IOP_CMD_OFFSET, 12)
                self.log_running = 0
            else:
                raise RuntimeError("No grove ADC log running.")

        def stop_log(self):
            """Stop recording the voltage values in the log.

            This can be done by calling the stop_log_raw() method.

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

            Returns
            -------
            None

            """
            if(self.log_running == 1):
                self.mmio.write(iop_const.MAILBOX_OFFSET+ \
                            iop_const.MAILBOX_PY2IOP_CMD_OFFSET, 12)
                self.log_running = 0
            else:
                raise RuntimeError("No grove ADC log running.")

        def get_log_raw(self):
            """Return list of logged raw samples.

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

            Returns
            -------
            list
                List of valid raw samples from the ADC sensor.

            """
            # Stop logging
            self.stop_log()

            # Prep iterators and results list
            head_ptr = self.mmio.read(iop_const.MAILBOX_OFFSET+0x8)
            tail_ptr = self.mmio.read(iop_const.MAILBOX_OFFSET+0xC)
            readings = list()

            # Sweep circular buffer for samples
            if head_ptr == tail_ptr:
                return None
            elif head_ptr < tail_ptr:
                for i in range(head_ptr,tail_ptr,4):
                    readings.append(self.mmio.read(i))
            else:
                for i in range(head_ptr,GROVE_ADC_LOG_END,4):
                    readings.append(self.mmio.read(i))
                for i in range(GROVE_ADC_LOG_START,tail_ptr,4):
                    readings.append(self.mmio.read(i))
            return readings

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

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

            Returns
            -------
            list
                List of valid voltage samples (floats) from the ADC sensor.

            """
            # Stop logging
            self.stop_log()

            # Prep iterators and results list
            head_ptr = self.mmio.read(iop_const.MAILBOX_OFFSET+0x8)
            tail_ptr = self.mmio.read(iop_const.MAILBOX_OFFSET+0xC)
            readings = list()

            # Sweep circular buffer for samples
            if head_ptr == tail_ptr:
                return None
            elif head_ptr < tail_ptr:
                for i in range(head_ptr,tail_ptr,4):
                    readings.append(float("{0:.4f}"\
                        .format(self._reg2float(self.mmio.read(i)))))
            else:
                for i in range(head_ptr,GROVE_ADC_LOG_END,4):
                    readings.append(float("{0:.4f}"\
                        .format(self._reg2float(self.mmio.read(i)))))
                for i in range(GROVE_ADC_LOG_START,tail_ptr,4):
                    readings.append(float("{0:.4f}"\
                        .format(self._reg2float(self.mmio.read(i)))))
            return readings

        def reset(self):
            """Resets/initializes the ADC.

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

            Returns
            -------
            None

            """
            # Send command and wait for acknowledge
            self.mmio.write(iop_const.MAILBOX_OFFSET + \
                            iop_const.MAILBOX_PY2IOP_CMD_OFFSET, 12)
            while (self.mmio.read(iop_const.MAILBOX_OFFSET + \
                                    iop_const.MAILBOX_PY2IOP_CMD_OFFSET) == 12):
                pass

        def _reg2float(self, reg):
            """Converts 32-bit register value to floats in Python.

            Parameters
            ----------
            reg: int
                A 32-bit register value read from the mailbox.

            Returns
            -------
            float
                A float number translated from the register value.

            """
            s = struct.pack('>l', reg)
            return struct.unpack('>f', s)[0]