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doc: Reference link fixes
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@ -24,5 +24,8 @@ The most commonly used features from the ARTIQ language modules and from the cor
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:mod:`artiq.language.units` module
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----------------------------------
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This module contains floating point constants that correspond to common physical units (ns, MHz, ...).
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They are provided for convenience (e.g write ``MHz`` instead of ``1000000.0``) and code clarity purposes.
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.. displays nothing, but makes references work
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.. automodule:: artiq.language.units
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:members:
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This module contains floating point constants that correspond to common physical units (ns, MHz, ...). They are provided for convenience (e.g write ``MHz`` instead of ``1000000.0``) and code clarity purposes.
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@ -21,7 +21,7 @@ As a very first step, we will turn on a LED on the core device. Create a file ``
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self.core.reset()
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self.led.on()
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The central part of our code is our ``LED`` class, which derives from :class:`~artiq.language.environment.EnvExperiment`. Almost all experiments should derive from this class, which provides access to the environment as well as including the necessary experiment framework from the base-level :class:`~artiq.language.environment.Experiment`. It will call our :meth:`~artiq.language.environment.build` at the right time and provides the :meth:`~artiq.language.environment.HasEnvironment.setattr_device` we use to gain access to our devices ``core`` and ``led``. The :func:`~artiq.language.core.kernel` decorator (``@kernel``) tells the system that the :meth:`~artiq.language.environment.Experiment.run` method is a kernel and must be compiled for and executed on the core device (instead of being interpreted and executed as regular Python code on the host).
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The central part of our code is our ``LED`` class, which derives from :class:`~artiq.language.environment.EnvExperiment`. Almost all experiments should derive from this class, which provides access to the environment as well as including the necessary experiment framework from the base-level :class:`~artiq.language.environment.Experiment`. It will call our :meth:`~artiq.language.environment.HasEnvironment.build` at the right time and provides the :meth:`~artiq.language.environment.HasEnvironment.setattr_device` we use to gain access to our devices ``core`` and ``led``. The :func:`~artiq.language.core.kernel` decorator (``@kernel``) tells the system that the :meth:`~artiq.language.environment.Experiment.run` method is a kernel and must be compiled for and executed on the core device (instead of being interpreted and executed as regular Python code on the host).
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Before you can run the example experiment, you need to supply ARTIQ with the device database for your system. This comes in the form of a Python script typically called ``device_db.py`` (see also the page :ref:`device-db`). If you purchased a system from M-Labs, the ``device_db.py`` for your system will normally already have been provided to you (either on the USB stick, inside ``~/artiq`` on the NUC, or by email). If you have the system description file for your configuration on hand, you can use the ARTIQ front-end tool ``artiq_ddb_template`` to generate a matching device database file. Otherwise, examples are available in the ``examples`` folder of ARTIQ, sorted into corresponding subfolders by core device, which you can edit to match your system.
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@ -71,11 +71,11 @@ You can then turn the LED off and on by entering 0 or 1 at the prompt that appea
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$ artiq_run led.py
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Enter desired LED state: 0
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What happens is that the ARTIQ compiler notices that the :meth:`input_led_state` function does not have a ``@kernel`` decorator (:func:`~artiq.language.core.kernel`) and thus must be executed on the host. When the function is called on the core device, it sends a request to the host, which executes it. The core device waits until the host returns, and then continues the kernel; in this case, the host displays the prompt, collects user input, and the core device sets the LED state accordingly.
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What happens is that the ARTIQ compiler notices that the ``input_led_state`` function does not have a ``@kernel`` decorator (:func:`~artiq.language.core.kernel`) and thus must be executed on the host. When the function is called on the core device, it sends a request to the host, which executes it. The core device waits until the host returns, and then continues the kernel; in this case, the host displays the prompt, collects user input, and the core device sets the LED state accordingly.
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The return type of all RPC functions must be known in advance. If the return value is not ``None``, the compiler requires a type annotation, like ``-> TBool`` in the example above. See also :ref:`compiler-types`.
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Without the :meth:`~artiq.coredevice.core.Core.break_realtime` call, the RTIO events emitted by :func:`self.led.on()` or :func:`self.led.off()` would be scheduled at a fixed and very short delay after entering :meth:`~artiq.language.environment.Experiment.run()`. These events would fail because the RPC to :meth:`input_led_state()` can take an arbitrarily long amount of time, and therefore the deadline for the submission of RTIO events would have long passed when :func:`self.led.on()` or :func:`self.led.off()` are called (that is, the ``rtio_counter_mu`` wall clock will have advanced far ahead of the timeline cursor ``now_mu``, and an :exc:`~artiq.coredevice.exceptions.RTIOUnderflow` would result; see :ref:`artiq-real-time-i-o-concepts` for the full explanation of wall clock vs. timeline.) The :meth:`~artiq.coredevice.core.Core.break_realtime` call is necessary to waive the real-time requirements of the LED state change. Rather than delaying by any particular time interval, it reads ``rtio_counter_mu`` and moves up the ``now_mu`` cursor far enough to ensure it's once again safely ahead of the wall clock.
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Without the :meth:`~artiq.coredevice.core.Core.break_realtime` call, the RTIO events emitted by :meth:`self.led.on() <artiq.coredevice.ttl.TTLInOut.on>` or :meth:`self.led.off() <artiq.coredevice.ttl.TTLInOut.off>` would be scheduled at a fixed and very short delay after entering :meth:`~artiq.language.environment.Experiment.run()`. These events would fail because the RPC to ``input_led_state()`` can take an arbitrarily long amount of time, and therefore the deadline for the submission of RTIO events would have long passed when :meth:`self.led.on() <artiq.coredevice.ttl.TTLInOut.on>` or :meth:`self.led.off() <artiq.coredevice.ttl.TTLInOut.off>` are called (that is, the ``rtio_counter_mu`` wall clock will have advanced far ahead of the timeline cursor ``now_mu``, and an :exc:`~artiq.coredevice.exceptions.RTIOUnderflow` would result; see :ref:`artiq-real-time-i-o-concepts` for the full explanation of wall clock vs. timeline.) The :meth:`~artiq.coredevice.core.Core.break_realtime` call is necessary to waive the real-time requirements of the LED state change. Rather than delaying by any particular time interval, it reads ``rtio_counter_mu`` and moves up the ``now_mu`` cursor far enough to ensure it's once again safely ahead of the wall clock.
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Real-time Input/Output (RTIO)
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-----------------------------
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@ -100,7 +100,7 @@ Create a new file ``rtio.py`` containing the following: ::
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delay(2*us)
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self.ttl0.pulse(2*us)
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In its :meth:`~artiq.language.environment.Experiment.build` method, the experiment obtains the core device and a TTL device called ``ttl0`` as defined in the device database.
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In its :meth:`~artiq.language.environment.HasEnvironment.build` method, the experiment obtains the core device and a TTL device called ``ttl0`` as defined in the device database.
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In ARTIQ, TTL is used roughly synonymous with "a single generic digital signal" and does not refer to a specific signaling standard or voltage/current levels.
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When :meth:`~artiq.language.environment.Experiment.run`, the experiment first ensures that ``ttl0`` is in output mode and actively driving the device it is connected to.
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@ -240,7 +240,7 @@ Non-RTIO devices and the controller manager
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As described in :ref:`artiq-real-time-i-o-concepts`, there are two classes of equipment a laboratory typically finds itself needing to operate. So far, we have largely discussed ARTIQ in terms of one only: the kind of specialized hardware that requires the very high-resolution timing control ARTIQ provides. The other class comprises the broad range of regular, "slow" laboratory devices, which do *not* require nanosecond precision and can generally be operated perfectly well from a regular PC over a non-realtime channel such as USB.
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To handle these "slow" devices, ARTIQ uses *controllers*, intermediate pieces of software which are responsible for the direct I/O to these devices and offer RPC interfaces to the network. Controllers can be started and run standalone, but are generally handled through the *controller manager*, :mod:`~artiq_comtools.artiq_ctlmgr`, available through the ``artiq-comtools`` package (normally automatically installed together with ARTIQ.) The controller manager in turn communicates with the ARTIQ master, and through it with clients or the GUI.
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To handle these "slow" devices, ARTIQ uses *controllers*, intermediate pieces of software which are responsible for the direct I/O to these devices and offer RPC interfaces to the network. Controllers can be started and run standalone, but are generally handled through the *controller manager*, available through the ``artiq-comtools`` package (normally automatically installed together with ARTIQ.) The controller manager in turn communicates with the ARTIQ master, and through it with clients or the GUI.
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To start the controller manager (the master must already be running), the only command necessary is: ::
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@ -394,7 +394,7 @@ To flash the idle kernel, first compile an idle experiment. Since the core devic
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The startup kernel is the kernel executed once immediately whenever the core device powers on. Uses include initializing DDSes, setting TTL directions etc. Proceed as with the idle kernel, but using the ``startup_kernel`` key in the ``artiq_coremgmt`` command.
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For DRTIO systems, the startup kernel should wait until the desired destinations (including local RTIO) are up, using :meth:`artiq.coredevice.Core.get_rtio_destination_status`.
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For DRTIO systems, the startup kernel should wait until the desired destinations (including local RTIO) are up, using :meth:`~artiq.coredevice.core.Core.get_rtio_destination_status`.
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Select the RTIO clock source
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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@ -88,7 +88,7 @@ This sequence is exactly equivalent to::
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ttl.pulse(2*us)
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This method :meth:`artiq.coredevice.ttl.TTLOut.pulse` advances the timeline cursor (using :func:`~artiq.language.core.delay` internally) by exactly the amount given. Other methods such as :meth:`~artiq.coredevice.ttl.TTLOut.on`, :meth:`~artiq.coredevice.ttl.TTLOut.off`, :meth:`~artiq.coredevice.ad9914.set` do not modify the timeline cursor. The latter are called *zero-duration* methods.
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This method :meth:`artiq.coredevice.ttl.TTLOut.pulse` advances the timeline cursor (using :func:`~artiq.language.core.delay` internally) by exactly the amount given. Other methods such as :meth:`~artiq.coredevice.ttl.TTLOut.on`, :meth:`~artiq.coredevice.ttl.TTLOut.off`, :meth:`~artiq.coredevice.ad9914.AD9914.set` do not modify the timeline cursor. The latter are called *zero-duration* methods.
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Output errors and exceptions
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----------------------------
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