Adding support for the minghe mhs5200 (#150)

* added mhs5200

* added minghe function generator

* added absolute_import

* fixed scaling on frequency

* switched to abstract instrument class

* fixed a few docstrings

* after testing with device

* Minghe MHS5200 - Add instrument to docs

* isolating changes from cc1 test station:

* Revert "isolating changes from cc1 test station:"

This reverts commit 87b8dec.

* reverting changes and fixing duty cycle

* Update for new FunctionGenerator multichannel consistency update

doc/examples/minghe/ex_minghe_mhs5200.py

@@ -0,0 +1,28 @@
+#!/usr/bin/python
+from instruments.minghe import MHS5200
+import quantities as pq
+
+mhs = MHS5200.open_serial(vid=6790, pid=29987, baud=57600)
+print(mhs.serial_number)
+mhs.channel[0].frequency = 3000000*pq.Hz
+print(mhs.channel[0].frequency)
+mhs.channel[0].function = MHS5200.Function.sawtooth_down
+print(mhs.channel[0].function)
+mhs.channel[0].amplitude = 9.0*pq.V
+print(mhs.channel[0].amplitude)
+mhs.channel[0].offset = -0.5
+print(mhs.channel[0].offset)
+mhs.channel[0].phase = 90
+print(mhs.channel[0].phase)
+
+mhs.channel[1].frequency = 2000000*pq.Hz
+print(mhs.channel[1].frequency)
+mhs.channel[1].function = MHS5200.Function.square
+print(mhs.channel[1].function)
+mhs.channel[1].amplitude = 2.0*pq.V
+print(mhs.channel[1].amplitude)
+mhs.channel[1].offset = 0.0
+print(mhs.channel[1].offset)
+mhs.channel[1].phase = 15
+print(mhs.channel[1].phase)
+

doc/source/apiref/minghe.rst

@@ -0,0 +1,15 @@
+..
+    TODO: put documentation license header here.
+    
+.. currentmodule:: instruments.minghe
+
+======
+Minghe
+======
+
+:class:`MHS5200` Function Generator
+===================================
+
+.. autoclass:: MHS5200
+    :members:
+    :undoc-members:

instruments/__init__.py

@@ -17,6 +17,7 @@
 from . import hp
 from . import keithley
 from . import lakeshore
+from . import minghe
 from . import newport
 from . import oxford
 from . import phasematrix

instruments/minghe/__init__.py

@@ -0,0 +1,7 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+"""
+Module containing MingHe instruments
+"""
+from __future__ import absolute_import
+from .mhs5200a import MHS5200

instruments/minghe/mhs5200a.py

@@ -0,0 +1,235 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+"""
+Provides the support for the MingHe low-cost function generator.
+
+Class originally contributed by Catherine Holloway.
+"""
+
+# IMPORTS #####################################################################
+
+from __future__ import absolute_import
+from __future__ import division
+
+from builtins import range
+from enum import Enum
+
+import quantities as pq
+from instruments.abstract_instruments import FunctionGenerator
+from instruments.util_fns import ProxyList, assume_units
+
+# CLASSES #####################################################################
+
+
+class MHS5200(FunctionGenerator):
+    """
+    The MHS5200 is a low-cost, 2 channel function generator.
+
+    There is no user manual, but Al Williams has reverse-engineered the
+    communications protocol:
+    https://github.com/wd5gnr/mhs5200a/blob/master/MHS5200AProtocol.pdf
+    """
+    def __init__(self, filelike):
+        super(MHS5200, self).__init__(filelike)
+        self._channel_count = 2
+        self.terminator = "\r\n"
+
+    def _ack_expected(self, msg=""):
+        if msg.find(":r") == 0:
+            return None
+        # most commands res
+        return "ok"
+
+    # INNER CLASSES #
+
+    class Channel(FunctionGenerator.Channel):
+        """
+        Class representing a channel on the MHS52000.
+        """
+        # pylint: disable=protected-access
+
+        __CHANNEL_NAMES = {
+            1: '1',
+            2: '2'
+        }
+
+        def __init__(self, mhs, idx):
+            self._mhs = mhs
+            super(MHS5200.Channel, self).__init__(parent=mhs, name=idx)
+            # Use zero-based indexing for the external API, but one-based
+            # for talking to the instrument.
+            self._idx = idx + 1
+            self._chan = self.__CHANNEL_NAMES[self._idx]
+            self._count = 0
+
+        def _get_amplitude_(self):
+            query = ":r{0}a".format(self._chan)
+            response = self._mhs.query(query)
+            return float(response.replace(query, ""))/100.0, self._mhs.VoltageMode.rms
+
+        def _set_amplitude_(self, magnitude, units):
+            if units == self._mhs.VoltageMode.peak_to_peak or \
+                            units == self._mhs.VoltageMode.rms:
+                magnitude = assume_units(magnitude, "V").rescale(pq.V).magnitude
+            elif units == self._mhs.VoltageMode.dBm:
+                raise NotImplementedError("Decibel units are not supported.")
+            magnitude *= 100
+            query = ":s{0}a{1}".format(self._chan, int(magnitude))
+            self._mhs.sendcmd(query)
+
+        @property
+        def duty_cycle(self):
+            """
+            Gets/Sets the duty cycle of this channel.
+
+            :units: A fraction
+            :type: `~quantities.Quantity`
+            """
+            query = ":r{0}d".format(self._chan)
+            response = self._mhs.query(query)
+            duty = float(response.replace(query, ""))/10.0
+            return duty
+
+        @duty_cycle.setter
+        def duty_cycle(self, new_val):
+            query = ":s{0}d{1}".format(self._chan, int(100.0*new_val))
+            self._mhs.sendcmd(query)
+
+        @property
+        def enable(self):
+            """
+            Gets/Sets the enable state of this channel.
+
+            :param newval: the enable state
+            :type: `bool`
+            """
+            query = ":r{0}b".format(self._chan)
+            return int(self._mhs.query(query).replace(query, "").
+                       replace("\r", ""))
+
+        @enable.setter
+        def enable(self, newval):
+            query = ":s{0}b{1}".format(self._chan, int(newval))
+            self._mhs.sendcmd(query)
+
+        @property
+        def frequency(self):
+            """
+            Gets/Sets the frequency of this channel.
+
+            :units: As specified (if a `~quantities.Quantity`) or assumed to be
+            of units hertz.
+            :type: `~quantities.Quantity`
+            """
+            query = ":r{0}f".format(self._chan)
+            response = self._mhs.query(query)
+            freq = float(response.replace(query, ""))*pq.Hz
+            return freq/100.0
+
+        @frequency.setter
+        def frequency(self, new_val):
+            new_val = assume_units(new_val, pq.Hz).rescale(pq.Hz).\
+                          magnitude*100.0
+            query = ":s{0}f{1}".format(self._chan, int(new_val))
+            self._mhs.sendcmd(query)
+
+        @property
+        def offset(self):
+            """
+            Gets/Sets the offset of this channel.
+
+            :param new_val: The fraction of the duty cycle to offset the
+            function by.
+            :type: `float`
+            """
+            # need to convert
+            query = ":r{0}o".format(self._chan)
+            response = self._mhs.query(query)
+            return int(response.replace(query, ""))/100.0-1.20
+
+        @offset.setter
+        def offset(self, new_val):
+            new_val = int(new_val*100)+120
+            query = ":s{0}o{1}".format(self._chan, new_val)
+            self._mhs.sendcmd(query)
+
+        @property
+        def phase(self):
+            """
+            Gets/Sets the phase of this channel.
+
+            :units: As specified (if a `~quantities.Quantity`) or assumed to be
+            of degrees.
+            :type: `~quantities.Quantity`
+            """
+            # need to convert
+            query = ":r{0}p".format(self._chan)
+            response = self._mhs.query(query)
+            return int(response.replace(query, ""))*pq.deg
+
+        @phase.setter
+        def phase(self, new_val):
+            new_val = assume_units(new_val, pq.deg).rescale("deg").magnitude
+            query = ":s{0}p{1}".format(self._chan, int(new_val))
+            self._mhs.sendcmd(query)
+
+        @property
+        def function(self):
+            """
+            Gets/Sets the wave type of this channel.
+
+            :type: `MHS5200.Function`
+            """
+            query = ":r{0}w".format(self._chan)
+            response = self._mhs.query(query).replace(query, "")
+            return self._mhs.Function(int(response))
+
+        @function.setter
+        def function(self, new_val):
+            query = ":s{0}w{1}".format(self._chan,
+                                       self._mhs.Function(new_val).value)
+            self._mhs.sendcmd(query)
+
+    class Function(Enum):
+        """
+        Enum containing valid wave modes for
+        """
+        sine = 0
+        square = 1
+        triangular = 2
+        sawtooth_up = 3
+        sawtooth_down = 4
+
+    @property
+    def channel(self):
+        """
+        Gets a specific channel object. The desired channel is specified like
+        one would access a list.
+
+        For instance, this would print the counts of the first channel::
+
+        >>> mhs = ik.minghe.MHS5200.open_serial(vid=1027, pid=24577,
+        baud=19200, timeout=1)
+        >>> print(mhs.channel[0].frequency)
+
+        :rtype: `list`[`MHS5200.Channel`]
+        """
+        return ProxyList(self, MHS5200.Channel, range(self._channel_count))
+
+    @property
+    def serial_number(self):
+        """
+        Get the serial number, as an int
+
+        :rtype: int
+        """
+        query = ":r0c"
+        response = self.query(query)
+        response = response.replace(query, "").replace("\r", "")
+        return response
+
+    def _get_amplitude_(self):
+        raise NotImplementedError()
+
+    def _set_amplitude_(self, magnitude, units):
+        raise NotImplementedError()