sawg: documentation

artiq/coredevice/sawg.py

@@ -13,13 +13,18 @@ class SAWG:
             i_enable*Re(oscillators) +
             q_enable*Im(buddy_oscillators))
 
-    Where:
+    The nine spline interpolators are accessible as attributes:
-        * offset, amplitude1, amplitude2: in units of full scale
+
-        * phase0, phase1, phase2: in units of turns
+    * :attr:`offset`, :attr:`amplitude1`, :attr:`amplitude2`: in units
-        * frequency0, frequency1, frequency2: in units of Hz
+      of full scale
+    * :attr:`phase0`, :attr:`phase1`, :attr:`phase2`: in units of turns
+    * :attr:`frequency0`, :attr:`frequency1`, :attr:`frequency2`: in units
+      of Hz
 
     :param channel_base: RTIO channel number of the first channel (amplitude).
         Frequency and Phase are then assumed to be successive channels.
+    :param parallelism: Number of output samples per coarse RTIO clock cycle.
+    :param core_device: Name of the core device that this SAWG is on.
     """
     kernel_invariants = {"channel_base", "core",
                          "amplitude1", "frequency1", "phase1",
@@ -34,21 +39,21 @@ class SAWG:
         cordic_gain = 1.646760258057163  # Cordic(width=16, guard=None).gain
         # cfg: channel_base
         self.offset = Spline(width, time_width, channel_base + 1,
-                             self.core, 1/2)
+                             self.core, 2.)
         self.amplitude1 = Spline(width, time_width, channel_base + 2,
-                                 self.core, 1/(2*cordic_gain**2))
+                                 self.core, 2*cordic_gain**2)
         self.frequency1 = Spline(3*width, time_width, channel_base + 3,
-                                 self.core, self.core.coarse_ref_period)
+                                 self.core, 1/self.core.coarse_ref_period)
         self.phase1 = Spline(width, time_width, channel_base + 4,
                              self.core, 1.)
         self.amplitude2 = Spline(width, time_width, channel_base + 5,
-                                 self.core, 1/(2*cordic_gain**2))
+                                 self.core, 2*cordic_gain**2)
         self.frequency2 = Spline(3*width, time_width, channel_base + 6,
-                                 self.core, self.core.coarse_ref_period)
+                                 self.core, 1/self.core.coarse_ref_period)
         self.phase2 = Spline(width, time_width, channel_base + 7,
                              self.core, 1.)
         self.frequency0 = Spline(2*width, time_width, channel_base + 8,
                                  self.core,
-                                 self.core.coarse_ref_period/parallelism)
+                                 parallelism/self.core.coarse_ref_period)
         self.phase0 = Spline(width, time_width, channel_base + 9,
                              self.core, 1.)

artiq/coredevice/spline.py

@@ -5,7 +5,7 @@ from artiq.language.types import TInt32, TInt64, TFloat
 
 
 class Spline:
-    """Spline interpolating RTIO channel.
+    r"""Spline interpolating RTIO channel.
 
     One knot of a polynomial basis spline (B-spline) :math:`u(t)`
     is defined by the coefficients :math:`u_n` up to order :math:`n = k`.
@@ -13,8 +13,15 @@ class Spline:
     :math:`u(t)` for :math:`t > t_0, t_0` is:
 
     .. math::
-        u(t) = \sum_{n=0}^k \frac{u_n}{n!} (t - t_0)^n
+        u(t) &= \sum_{n=0}^k \frac{u_n}{n!} (t - t_0)^n \\
-        = u_0 + u_1 (t - t_0) + \frac{u_2}{2} (t - t_0)^2 + \dots
+             &= u_0 + u_1 (t - t_0) + \frac{u_2}{2} (t - t_0)^2 + \dots
+
+    :param width: Width in bits of the quantity that this spline controls
+    :param time_width: Width in bits of the time counter of this spline
+    :param channel: RTIO channel number
+    :param core_device: Core device that this spline is attached to
+    :param scale: Scale for conversion between machine units and physical
+        units; to be given as the "full scale physical value".
     """
 
     kernel_invariants = {"channel", "core", "scale", "width",
@@ -24,7 +31,7 @@ class Spline:
         self.core = core_device
         self.channel = channel
         self.width = width
-        self.scale = float((int64(1) << width) * scale)
+        self.scale = float((int64(1) << width) / scale)
         self.time_width = time_width
         self.time_scale = float((1 << time_width) *
                                 core_device.coarse_ref_period)

doc/manual/core_drivers_reference.rst

@@ -10,7 +10,7 @@ These drivers are for the core device and the peripherals closely integrated int
     :members:
 
 :mod:`artiq.coredevice.ttl` module
------------------------------------
+----------------------------------
 
 .. automodule:: artiq.coredevice.ttl
     :members:
@@ -43,7 +43,7 @@ These drivers are for the core device and the peripherals closely integrated int
     :members:
 
 :mod:`artiq.coredevice.cache` module
------------------------------------------
+------------------------------------
 
 .. automodule:: artiq.coredevice.cache
     :members:
@@ -54,6 +54,12 @@ These drivers are for the core device and the peripherals closely integrated int
 .. automodule:: artiq.coredevice.exceptions
     :members:
 
+:mod:`artiq.coredevice.spline` module
+-------------------------------------
+
+.. automodule:: artiq.coredevice.spline
+    :members:
+
 :mod:`artiq.coredevice.sawg` module
 -----------------------------------
 
@@ -61,7 +67,7 @@ These drivers are for the core device and the peripherals closely integrated int
     :members:
 
 :mod:`artiq.coredevice.ad9154` module
------------------------------------
+-------------------------------------
 
 .. automodule:: artiq.coredevice.ad9154
     :members: