[rtems-docs commit] Remove Analog Driver chapter

Sebastian Huber sebh at rtems.org
Fri Dec 23 13:40:39 UTC 2016 

Module:    rtems-docs
Branch:    master
Commit:    4b5b49988d8eaf78ea58e1b290159632ab547c3a
Changeset: http://git.rtems.org/rtems-docs/commit/?id=4b5b49988d8eaf78ea58e1b290159632ab547c3a

Author:    Sebastian Huber <sebastian.huber at embedded-brains.de>
Date:      Tue Dec 20 11:23:57 2016 +0100

Remove Analog Driver chapter

There exists no standard Analog Driver in the RTEMS code base.

Close #2850.

---

 bsp-howto/analog.rst | 165 ---------------------------------------------------
 bsp-howto/index.rst  |   1 -
 2 files changed, 166 deletions(-)

diff --git a/bsp-howto/analog.rst b/bsp-howto/analog.rst
deleted file mode 100644
index 907e240..0000000
--- a/bsp-howto/analog.rst
+++ /dev/null
@@ -1,165 +0,0 @@
-.. comment SPDX-License-Identifier: CC-BY-SA-4.0
-
-.. COMMENT: COPYRIGHT (c) 1988-2002.
-.. COMMENT: On-Line Applications Research Corporation (OAR).
-.. COMMENT: All rights reserved.
-
-Analog Driver
-*************
-
-The Analog driver is responsible for providing an interface to Digital to
-Analog Converters (DACs) and Analog to Digital Converters (ADCs).  The
-capabilities provided by this class of device driver are:
-
-- Initialize an Analog Board
-
-- Open a Particular Analog
-
-- Close a Particular Analog
-
-- Read from a Particular Analog
-
-- Write to a Particular Analog
-
-- Reset DACs
-
-- Reinitialize DACS
-
-Most analog devices are found on I/O cards that support multiple DACs or ADCs
-on a single card.
-
-There are currently no analog device drivers included in the RTEMS source tree.
-The information provided in this chapter is based on drivers developed for
-applications using RTEMS.  It is hoped that this driver model information can
-form the basis for a standard analog driver model that can be supported in
-future RTEMS distribution.
-
-Major and Minor Numbers
-=======================
-
-The ``major`` number of a device driver is its index in the RTEMS Device
-Address Table.
-
-A ``minor`` number is associated with each device instance managed by a
-particular device driver.  An RTEMS minor number is an ``unsigned32`` entity.
-Convention calls for dividing the bits in the minor number down into categories
-like the following:
-
-- ``board`` - indicates the board a particular device is located on
-
-- ``port`` - indicates the particular device on a board.
-
-From the above, it should be clear that a single device driver can support
-multiple copies of the same board in a single system.  The minor number is used
-to distinguish the devices.
-
-Analog Driver Configuration
-===========================
-
-There is not a standard analog driver configuration table but some fields are
-common across different drivers.  The analog driver configuration table is
-typically an array of structures with each structure containing the information
-for a particular board.  The following is a list of the type of information
-normally required to configure an analog board:
-
-``board_offset``
-    is the base address of a board.
-
-``DAC_initial_values``
-    is an array of the voltages that should be written to each DAC during
-    initialization.  This allows the driver to start the board in a known
-    state.
-
-Initialize an Analog Board
-==========================
-
-At system initialization, the analog driver's initialization entry point will
-be invoked.  As part of initialization, the driver will perform whatever board
-initialization is required and then set all outputs to their configured initial
-state.
-
-The analog driver may register a device name for each DAC and ADC in the
-system.
-
-Open a Particular Analog
-========================
-
-This is the driver open call.  Usually this call does nothing other than
-validate the minor number.
-
-With some drivers, it may be necessary to allocate memory when a particular
-device is opened.  If that is the case, then this is often the place to do this
-operation.
-
-Close a Particular Analog
-=========================
-
-This is the driver close call.  Usually this call does nothing.
-
-With some drivers, it may be necessary to allocate memory when a particular
-device is opened.  If that is the case, then this is the place where that
-memory should be deallocated.
-
-Read from a Particular Analog
-=============================
-
-This corresponds to the driver read call.  After validating the minor number
-and arguments, this call reads the indicated device.  Most analog devices store
-the last value written to a DAC.  Since DACs are output only devices, saving
-the last written value gives the appearance that DACs can be read from also.
-If the device is an ADC, then it is sampled.
-
-.. note::
-
-   Many boards have multiple analog inputs but only one ADC.  On these boards,
-   it will be necessary to provide some type of mutual exclusion during reads.
-   On these boards, there is a MUX which must be switched before sampling the
-   ADC.  After the MUX is switched, the driver must delay some short period of
-   time (usually microseconds) before the signal is stable and can be sampled.
-   To make matters worse, some ADCs cannot respond to wide voltage swings in a
-   single sample.  On these ADCs, one must do two samples when the voltage
-   swing is too large.  On a practical basis, this means that the driver
-   usually ends up double sampling the ADC on these systems.
-
-The value returned is a single precision floating point number representing the
-voltage read.  This value is stored in the ``argument_block`` passed in to the
-call.  By returning the voltage, the caller is freed from having to know the
-number of bits in the analog and board dependent conversion algorithm.
-
-Write to a Particular Analog
-============================
-
-This corresponds to the driver write call.  After validating the minor number
-and arguments, this call writes the indicated device.  If the specified device
-is an ADC, then an error is usually returned.
-
-The value written is a single precision floating point number representing the
-voltage to be written to the specified DAC.  This value is stored in the
-``argument_block`` passed in to the call.  By passing the voltage to the device
-driver, the caller is freed from having to know the number of bits in the
-analog and board dependent conversion algorithm.
-
-Reset DACs
-==========
-
-This is one of the IOCTL functions supported by the I/O control device driver
-entry point.  When this IOCTL function is invoked, all of the DACs are written
-to 0.0 volts.
-
-Reinitialize DACS
-=================
-
-This is one of the IOCTL functions supported by the I/O control device driver
-entry point.  When this IOCTL function is invoked, all of the DACs are written
-with the initial value configured for this device.
-
-Get Last Written Values
-=======================
-
-This is one of the IOCTL functions supported by the I/O control device driver
-entry point.  When this IOCTL function is invoked, the following information is
-returned to the caller:
-
-- last value written to the specified DAC
-
-- timestamp of when the last write was performed
diff --git a/bsp-howto/index.rst b/bsp-howto/index.rst
index 649e335..31cc0fa 100644
--- a/bsp-howto/index.rst
+++ b/bsp-howto/index.rst
@@ -57,7 +57,6 @@ to the Community Project hosted at http://www.rtems.org.
 	networking
 	shared_memory_support
 	frame_buffer
-	analog
 	discrete
 	command

More information about the vc mailing list