Standardise and add documentation for creating new StandardDetector i…

…mplementations (#281)

* Remove ScalarSigs (see issue #282)

docs/examples/foo_detector.py

@@ -0,0 +1,82 @@
+import asyncio
+from typing import Optional
+
+from bluesky.protocols import HasHints, Hints
+
+from ophyd_async.core import DirectoryProvider
+from ophyd_async.core.async_status import AsyncStatus
+from ophyd_async.core.detector import DetectorControl, DetectorTrigger, StandardDetector
+from ophyd_async.epics.areadetector.drivers.ad_base import (
+    ADBase,
+    ADBaseShapeProvider,
+    start_acquiring_driver_and_ensure_status,
+)
+from ophyd_async.epics.areadetector.utils import ImageMode, ad_rw, stop_busy_record
+from ophyd_async.epics.areadetector.writers.hdf_writer import HDFWriter
+from ophyd_async.epics.areadetector.writers.nd_file_hdf import NDFileHDF
+
+
+class FooDriver(ADBase):
+    def __init__(self, prefix: str, name: str = "") -> None:
+        self.trigger_mode = ad_rw(str, prefix + "TriggerMode")
+        super().__init__(prefix, name)
+
+
+class FooController(DetectorControl):
+    def __init__(self, driver: FooDriver) -> None:
+        self._drv = driver
+
+    def get_deadtime(self, exposure: float) -> float:
+        # FooDetector deadtime handling
+        return 0.001
+
+    async def arm(
+        self,
+        num: int,
+        trigger: DetectorTrigger = DetectorTrigger.internal,
+        exposure: Optional[float] = None,
+    ) -> AsyncStatus:
+        await asyncio.gather(
+            self._drv.num_images.set(num),
+            self._drv.image_mode.set(ImageMode.multiple),
+            self._drv.trigger_mode.set(f"FOO{trigger}"),
+        )
+        if exposure is not None:
+            await self._drv.acquire_time.set(exposure)
+        return await start_acquiring_driver_and_ensure_status(self._drv)
+
+    async def disarm(self):
+        await stop_busy_record(self._drv.acquire, False, timeout=1)
+
+
+class FooDetector(StandardDetector, HasHints):
+    _controller: FooController
+    _writer: HDFWriter
+
+    def __init__(
+        self,
+        prefix: str,
+        directory_provider: DirectoryProvider,
+        drv_suffix="cam1:",
+        hdf_suffix="HDF1:",
+        name="",
+    ):
+        # Must be children to pick up connect
+        self.drv = FooDriver(prefix + drv_suffix)
+        self.hdf = NDFileHDF(prefix + hdf_suffix)
+
+        super().__init__(
+            FooController(self.drv),
+            HDFWriter(
+                self.hdf,
+                directory_provider,
+                lambda: self.name,
+                ADBaseShapeProvider(self.drv),
+            ),
+            config_sigs=(self.drv.acquire_time,),
+            name=name,
+        )
+
+    @property
+    def hints(self) -> Hints:
+        return self._writer.hints

docs/how-to/make-a-standard-detector.rst

@@ -0,0 +1,64 @@
+.. note::
+
+   Ophyd async is included on a provisional basis until the v1.0 release and 
+   may change API on minor release numbers before then
+
+Make a StandardDetector
+=======================
+
+`StandardDetector` is an abstract class to assist in creating Device classes for hardware that writes its own data e.g. an AreaDetector implementation, or a PandA writing motor encoder positions to file.
+The `StandardDetector` is a simple compound device, with 2 standard components: 
+
+- `DetectorWriter` to handle data persistence, i/o and pass information about data to the RunEngine (usually an instance of :py:class:`HDFWriter`)
+- `DetectorControl` with logic for arming and disarming the detector. This will be unique to the StandardDetector implementation.
+
+Writing an AreaDetector StandardDetector
+----------------------------------------
+
+For an AreaDetector implementation of the StandardDetector, two entity objects which are subdevices of the `StandardDetector` are used to map to AreaDetector plugins:
+
+- An NDPluginFile instance (for :py:class:`HDFWriter` an instance of :py:class:`NDFileHDF`)
+- An :py:class:`ADBase` instance mapping to NDArray for the "driver" of the detector implementation
+
+
+Define a :py:class:`FooDriver` if the NDArray requires fields in addition to those on :py:class:`ADBase` to be exposed. It should extend :py:class:`ADBase`.
+Enumeration fields should be named to prevent namespace collision, i.e. for a Signal named "TriggerSource" use the enum "FooTriggerSource"
+
+.. literalinclude:: ../examples/foo_detector.py
+   :language: python
+   :pyobject: FooDriver
+
+Define a :py:class:`FooController` with handling for converting the standard pattern of :py:meth:`ophyd_async.core.DetectorControl.arm` and :py:meth:`ophyd_async.core.DetectorControl.disarm` to required state of :py:class:`FooDriver` e.g. setting a compatible "FooTriggerSource" for a given `DetectorTrigger`, or raising an exception if incompatible with the `DetectorTrigger`.
+
+The :py:meth:`ophyd_async.core.DetectorControl.get_deadtime` method is used when constructing sequence tables for hardware controlled scanning. Details on how to calculate the deadtime may be only available from technical manuals or otherwise complex. **If it requires fetching from signals, it is recommended to cache the value during the StandardDetector `prepare` method.**
+
+.. literalinclude:: ../examples/foo_detector.py
+   :pyobject: FooController
+
+:py:class:`FooDetector` ties the Driver, Controller and data persistence layer together. The example :py:class:`FooDetector` writes h5 files using the standard NDPlugin. It additionally supports the :py:class:`HasHints` protocol which is optional but recommended.
+
+Its initialiser assumes the NSLS-II AreaDetector plugin EPICS address suffixes as defaults but allows overriding: **this pattern is recommended for consistency**.
+If the :py:class:`FooDriver` signals that should be read as configuration, they should be added to the "config_sigs" passed to the super.
+
+.. literalinclude:: ../examples/foo_detector.py
+   :pyobject: FooDetector
+
+
+Writing a non-AreaDetector StandardDetector
+-------------------------------------------
+
+A non-AreaDetector `StandardDetector` should implement `DetectorControl` and `DetectorWriter` directly.
+Here we construct a `DetectorControl` that co-ordinates signals on a PandA PositionCapture block - a child device "pcap" of the `StandardDetector` implementation, analogous to the :py:class:`FooDriver`.
+
+.. literalinclude:: ../../src/ophyd_async/panda/_panda_controller.py
+   :pyobject: PandaPcapController
+
+The PandA may write a number of fields, and the :py:class:`PandaHDFWriter` co-ordinates those, configures the filewriter and describes the data for the RunEngine.
+
+.. literalinclude:: ../../src/ophyd_async/panda/writers/_hdf_writer.py
+   :pyobject: PandaHDFWriter
+
+The PandA StandardDetector implementation simply ties the component parts and its child devices together.
+
+.. literalinclude:: ../../src/ophyd_async/panda/_hdf_panda.py
+   :pyobject: HDFPanda

src/ophyd_async/epics/areadetector/aravis.py

@@ -23,16 +23,15 @@ class AravisDetector(StandardDetector, HasHints):
 
     def __init__(
         self,
-        name: str,
+        prefix: str,
         directory_provider: DirectoryProvider,
-        driver: AravisDriver,
-        hdf: NDFileHDF,
+        drv_suffix="cam1:",
+        hdf_suffix="HDF1:",
+        name="",
         gpio_number: AravisController.GPIO_NUMBER = 1,
-        **scalar_sigs: str,
     ):
-        # Must be child of Detector to pick up connect()
-        self.drv = driver
-        self.hdf = hdf
+        self.drv = AravisDriver(prefix + drv_suffix)
+        self.hdf = NDFileHDF(prefix + hdf_suffix)
 
         super().__init__(
             AravisController(self.drv, gpio_number=gpio_number),
@@ -41,9 +40,8 @@ def __init__(
                 directory_provider,
                 lambda: self.name,
                 ADBaseShapeProvider(self.drv),
-                **scalar_sigs,
             ),
-            config_sigs=(self.drv.acquire_time, self.drv.acquire),
+            config_sigs=(self.drv.acquire_time,),
             name=name,
         )
 

src/ophyd_async/epics/areadetector/kinetix.py

@@ -20,15 +20,14 @@ class KinetixDetector(StandardDetector, HasHints):
 
     def __init__(
         self,
-        name: str,
+        prefix: str,
         directory_provider: DirectoryProvider,
-        driver: KinetixDriver,
-        hdf: NDFileHDF,
-        **scalar_sigs: str,
+        drv_suffix="cam1:",
+        hdf_suffix="HDF1:",
+        name="",
     ):
-        # Must be child of Detector to pick up connect()
-        self.drv = driver
-        self.hdf = hdf
+        self.drv = KinetixDriver(prefix + drv_suffix)
+        self.hdf = NDFileHDF(prefix + hdf_suffix)
 
         super().__init__(
             KinetixController(self.drv),
@@ -37,9 +36,8 @@ def __init__(
                 directory_provider,
                 lambda: self.name,
                 ADBaseShapeProvider(self.drv),
-                **scalar_sigs,
             ),
-            config_sigs=(self.drv.acquire_time, self.drv.acquire),
+            config_sigs=(self.drv.acquire_time,),
             name=name,
         )
 

src/ophyd_async/epics/areadetector/pilatus.py

@@ -1,10 +1,7 @@
-from typing import Optional, Sequence
-
 from bluesky.protocols import Hints
 
 from ophyd_async.core import DirectoryProvider
 from ophyd_async.core.detector import StandardDetector
-from ophyd_async.core.signal import SignalR
 from ophyd_async.epics.areadetector.controllers.pilatus_controller import (
     PilatusController,
 )
@@ -22,15 +19,14 @@ class PilatusDetector(StandardDetector):
 
     def __init__(
         self,
-        name: str,
+        prefix: str,
         directory_provider: DirectoryProvider,
-        driver: PilatusDriver,
-        hdf: NDFileHDF,
-        config_sigs: Optional[Sequence[SignalR]] = None,
-        **scalar_sigs: str,
+        drv_suffix="cam1:",
+        hdf_suffix="HDF1:",
+        name="",
     ):
-        self.drv = driver
-        self.hdf = hdf
+        self.drv = PilatusDriver(prefix + drv_suffix)
+        self.hdf = NDFileHDF(prefix + hdf_suffix)
 
         super().__init__(
             PilatusController(self.drv),
@@ -39,9 +35,8 @@ def __init__(
                 directory_provider,
                 lambda: self.name,
                 ADBaseShapeProvider(self.drv),
-                **scalar_sigs,
             ),
-            config_sigs=config_sigs or (self.drv.acquire_time,),
+            config_sigs=(self.drv.acquire_time,),
             name=name,
         )
 

src/ophyd_async/epics/areadetector/vimba.py

@@ -17,15 +17,14 @@ class VimbaDetector(StandardDetector, HasHints):
 
     def __init__(
         self,
-        name: str,
+        prefix: str,
         directory_provider: DirectoryProvider,
-        driver: VimbaDriver,
-        hdf: NDFileHDF,
-        **scalar_sigs: str,
+        drv_suffix="cam1:",
+        hdf_suffix="HDF1:",
+        name="",
     ):
-        # Must be child of Detector to pick up connect()
-        self.drv = driver
-        self.hdf = hdf
+        self.drv = VimbaDriver(prefix + drv_suffix)
+        self.hdf = NDFileHDF(prefix + hdf_suffix)
 
         super().__init__(
             VimbaController(self.drv),
@@ -34,9 +33,8 @@ def __init__(
                 directory_provider,
                 lambda: self.name,
                 ADBaseShapeProvider(self.drv),
-                **scalar_sigs,
             ),
-            config_sigs=(self.drv.acquire_time, self.drv.acquire),
+            config_sigs=(self.drv.acquire_time,),
             name=name,
         )
 

tests/epics/areadetector/test_aravis.py

@@ -11,40 +11,15 @@
     set_sim_value,
 )
 from ophyd_async.epics.areadetector.aravis import AravisDetector
-from ophyd_async.epics.areadetector.drivers.aravis_driver import AravisDriver
-from ophyd_async.epics.areadetector.writers.nd_file_hdf import NDFileHDF
-
-
-@pytest.fixture
-async def adaravis_driver(RE: RunEngine) -> AravisDriver:
-    async with DeviceCollector(sim=True):
-        driver = AravisDriver("DRV:")
-
-    return driver
-
-
-@pytest.fixture
-async def hdf(RE: RunEngine) -> NDFileHDF:
-    async with DeviceCollector(sim=True):
-        hdf = NDFileHDF("HDF:")
-
-    return hdf
 
 
 @pytest.fixture
 async def adaravis(
     RE: RunEngine,
     static_directory_provider: DirectoryProvider,
-    adaravis_driver: AravisDriver,
-    hdf: NDFileHDF,
 ) -> AravisDetector:
     async with DeviceCollector(sim=True):
-        adaravis = AravisDetector(
-            "adaravis",
-            static_directory_provider,
-            driver=adaravis_driver,
-            hdf=hdf,
-        )
+        adaravis = AravisDetector("ADARAVIS:", static_directory_provider)
 
     return adaravis
 

tests/epics/areadetector/test_kinetix.py

@@ -7,41 +7,16 @@
     DirectoryProvider,
     set_sim_value,
 )
-from ophyd_async.epics.areadetector.drivers.kinetix_driver import KinetixDriver
 from ophyd_async.epics.areadetector.kinetix import KinetixDetector
-from ophyd_async.epics.areadetector.writers.nd_file_hdf import NDFileHDF
-
-
-@pytest.fixture
-async def adkinetix_driver(RE: RunEngine) -> KinetixDriver:
-    async with DeviceCollector(sim=True):
-        driver = KinetixDriver("DRV:")
-
-    return driver
-
-
-@pytest.fixture
-async def hdf(RE: RunEngine) -> NDFileHDF:
-    async with DeviceCollector(sim=True):
-        hdf = NDFileHDF("HDF:")
-
-    return hdf
 
 
 @pytest.fixture
 async def adkinetix(
     RE: RunEngine,
     static_directory_provider: DirectoryProvider,
-    adkinetix_driver: KinetixDriver,
-    hdf: NDFileHDF,
 ) -> KinetixDetector:
     async with DeviceCollector(sim=True):
-        adkinetix = KinetixDetector(
-            "adkinetix",
-            static_directory_provider,
-            driver=adkinetix_driver,
-            hdf=hdf,
-        )
+        adkinetix = KinetixDetector("KINETIX:", static_directory_provider)
 
     return adkinetix