pxi6733: add mediator

artiq/devices/pxi6733/mediator.py

@@ -0,0 +1,182 @@
+import numpy as np
+
+from artiq.language.core import *
+from artiq.language.db import *
+from artiq.language.units import *
+from artiq.wavesynth.compute_samples import Synthesizer
+
+
+class SegmentSequenceError(Exception):
+    """Raised when attempting to play back a named segment which is not the
+    next in the sequence."""
+    pass
+
+
+class InvalidatedError(Exception):
+    """Raised when attemting to use a frame or segment that has been
+    invalidated (due to disarming the DAQmx)."""
+    pass
+
+
+class ArmError(Exception):
+    """Raised when attempting to arm an already armed DAQmx, to modify the
+    program of an armed DAQmx, or to play a segment on a disarmed DAQmx."""
+    pass
+
+
+def _ceil_div(a, b):
+    return (a + b - 1)//b
+
+
+def _compute_duration_mu(nsamples, ftw, acc_width):
+    # This returns the precise duration so that the clock can be stopped
+    # exactly at the next rising edge (RTLink commands take precedence over
+    # toggling from the accumulator).
+    # If segments are played continuously, replacement of the stop command
+    # will keep the clock running. If the FTW is not a power of two, note that
+    # the accumulator is reset at that time, which causes jitter and frequency
+    # inaccuracy.
+    # Formally:
+    #    duration     *ftw >= nsamples*2**acc_width
+    #   (duration - 1)*ftw <  nsamples*2**acc_width 
+    return _ceil_div(nsamples*2**acc_width, ftw)
+
+
+class _Segment:
+    def __init__(self, frame, segment_number):
+        self.frame = frame
+        self.segment_number = segment_number
+
+        self.lines = []
+
+        # for @kernel
+        self.core = frame.daqmx.core
+
+    def add_line(self, duration, channel_data):
+        if self.frame.invalidated:
+            raise InvalidatedError
+        if self.frame.daqmx.armed:
+            raise ArmError
+        self.lines.append((duration, channel_data))
+
+    @kernel
+    def advance(self):
+        if self.frame.invalidated:
+            raise InvalidatedError
+        if not self.frame.daqmx.armed:
+            raise ArmError
+        # If the frame is currently being played, check that we are next.
+        if (self.frame.daqmx.next_segment >= 0
+                and self.frame.daqmx.next_segment != self.segment_number):
+            raise SegmentSequenceError
+        self.frame.advance()
+
+
+class _Frame:
+    def __init__(self, daqmx):
+        self.daqmx = daqmx
+        self.segments = []
+        self.segment_count = 0  # == len(self.segments), used in kernel
+
+        self.invalidated = False
+
+        # for @kernel
+        self.core = self.daqmx.core
+
+    def create_segment(self, name=None):
+        if self.invalidated:
+            raise InvalidatedError
+        if self.daqmx.armed:
+            raise ArmError
+        segment = _Segment(self, self.segment_count)
+        if name is not None:
+            if hasattr(self, name):
+                raise NameError("Segment name already exists")
+            setattr(self, name, segment)
+        self.segments.append(segment)
+        self.segment_count += 1
+        return segment
+
+    def _arm(self):
+        self.segment_delays = [
+            _compute_duration_mu(s.get_sample_count(),
+                                 self.daqmx.sample_rate,
+                                 self.daqmx.clock.acc_width)
+            for s in self.segments]
+
+    def _invalidate(self):
+        self.invalidated = True
+
+    def _get_samples(self):
+        program = [
+            {
+                "dac_divider": 1,
+                "duration": duration,
+                "channel_data": channel_data,
+            } for duration, channel_data in segment.lines 
+                for segment in self.segments]
+        synth = Synthesizer(self.daqmx.channel_count, program)
+        synth.select(0)
+        # not setting any trigger flag in the program causes the whole
+        # waveform to be computed here for all segments.
+        # slicing the segments is done by stopping the clock.
+        return synth.trigger()
+
+    @kernel
+    def advance(self):
+        if self.invalidated:
+            raise InvalidatedError
+        if not self.daqmx.armed:
+            raise ArmError
+
+        self.daqmx.clock.set(self.daqmx.sample_rate)
+        delay_mu(self.segment_delays[self.daqmx.next_segment])
+        self.daqmx.next_segment += 1
+        self.daqmx.clock.stop()
+
+        # test for end of frame
+        if self.daqmx.next_segment == self.segment_count:
+            self.daqmx.next_segment = -1
+
+
+class CompoundDAQmx(AutoDB):
+    class DBKeys:
+        core = Device()
+        daqmx_device = Argument()
+        clock_device = Argument()
+        channel_count = Argument()
+        sample_rate = Argument()
+        sample_rate_in_mu = Argument(False)
+
+    def build(self):
+        self.daqmx = self.dbh.get_device(self.daqmx_device)
+        self.clock = self.dbh.get_device(self.clock_device)
+
+        if not self.sample_rate_in_mu:
+            self.sample_rate = self.clock.frequency_to_ftw(sample_rate)
+
+        self.frame = None
+        self.next_segment = -1
+        self.armed = False
+
+    def disarm(self):
+        if self.frame is not None:
+            self.frame._invalidate()
+        self.frame = None
+        self.armed = False
+
+    def arm(self):
+        if self.armed:
+            raise ArmError
+        if self.frame is not None:
+            self.frame._arm()
+            self.daqmx.load_sample_values(
+                self.clock.ftw_to_frequency(self.sample_rate),
+                np.array(self.frame._get_samples()))
+        self.armed = True
+
+    def create_frame(self):
+        if self.armed:
+            raise ArmError
+        self.frame = _Frame(self)
+        return self.frame