tinySA/os/io/io.dox

/*
    ChibiOS/RT - Copyright (C) 2006-2007 Giovanni Di Sirio.

    This file is part of ChibiOS/RT.

    ChibiOS/RT is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 3 of the License, or
    (at your option) any later version.

    ChibiOS/RT is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/


/**
 * @defgroup IO I/O
 * @brief I/O related services.
 * @details This section contains the I/O related services.
 *
 * The I/O subsystem is a collection of device driver poertable interfaces and
 * platform dependent implementations.<br>
 * Under ChibiOS/RT a device driver is split in two layers:
 * - High Level Device Driver (<b>HLD</b>). This layer contains the definitions
 *   of the driver's APIs and the platform independent part of the driver.<br>
 *   An HLD is composed by two files:
 *   - @<driver@>.c, the high level implementation file. This file must be
 *     included in the Makefile in order to use the driver.
 *   - @<driver@>.h, the high level header file. This file must be included
 *     by the application code in order to access the driver's APIs.
 *   .
 * - Low Level Device Driver (<b>LLD</b>). This layer contains the platform
 *   dependent part of the driver.<br>
 *   A LLD is composed by two files:
 *   - @<driver@>_lld.c, the low level implementation file. This file must be
 *     included in the Makefile in order to use the driver.
 *   - @<driver@>_lld.h, the high level header file. This file is implicitly
 *     included by the HLD header file.
 *   .
 * .
 * <h2>Available Device Drivers</h2>
 * The I/O subsystem currently includes support for:
 * - @ref PAL.
 * - @ref SERIAL.
 * .
 */

/**
 * @defgroup PAL Ports Abstraction Layer (PAL)
 * @brief I/O Ports Abstraction Layer
 * @details This module defines an abstract interface for digital I/O ports.
 * Note that most I/O ports functions are just macros. The macros
 * have default software implementations that can be redefined in a
 * @ref PAL_LLD if the target hardware supports special features like, as
 * example, atomic bit set/reset/masking. Please refer to the ports specific
 * documentation for details.<br>
 * The @ref PAL has the advantage to make the access to the I/O ports platform
 * independent and still be optimized for the specific architectures.<br>
 * Note that the @ref PAL_LLD may also offer non standard macro and functions
 * in order to support specific features but, of course, the use of such
 * interfaces would not be portable. Such interfaces shall be marked with
 * the architecture name inside the function names.
 *
 * <h2>Implementation Rules</h2>
 * In implementing an @ref PAL_LLD there are some rules/behaviors that
 * should be respected.
 *
 * <h3>Writing on input pads</h3>
 * The behavior is not specified but there are implementations better than
 * others, this is the list of possible implementations, preferred options
 * are on top:
 * -# The written value is not actually output but latched, should the pads
 *    be reprogrammed as outputs the value would be in effect.
 * -# The write operation is ignored.
 * -# The write operation has side effects, as example disabling/enabling
 *    pull up/down resistors or changing the pad direction. This scenario is
 *    discouraged, please try to avoid this scenario.
 * .
 * <h3>Reading from output pads</h3>
 * The behavior is not specified but there are implementations better than
 * others, this is the list of possible implementations, preferred options
 * are on top:
 * -# The actual pads states are read (not the output latch).
 * -# The output latch value is read (regardless of the actual pads states).
 * -# Unspecified, please try to avoid this scenario.
 * .
 * <h3>Writing unused or unimplemented port bits</h3>
 * The behavior is not specified.
 *
 * <h3>Reading from unused or unimplemented port bits</h3>
 * The behavior is not specified.
 *
 * <h3>Reading or writing on pins associated to other functionalities</h3>
 * The behavior is not specified.
 *
 * <h2>Usage</h2>
 * The use of I/O ports requires the inclusion of the header file @p pal.h,
 * this file is not automatically included @p ch.h like the other header
 * files.
 *
 * @ingroup IO
 */

/**
 * @defgroup PAL_LLD PAL Low Level Driver Template
 * @brief @ref PAL low level driver template.
 * @details This file is a template for an I/O port low level driver.
 *
 * @ingroup PAL
 */

/**
 * @defgroup SERIAL Serial Driver
 * @brief Generic Serial Drivers.
 * @details This module implements a generic full duplex serial driver. The
 * driver implements a @p SerialDriver interface and uses I/O Queues for
 * communication between the upper and the lower driver. Event flags are used
 * to notify the application about incoming data, outgoing data and other I/O
 * events.<br>
 * The  module also contains functions that make the implementation of the
 * interrupt service routines much easier.<br>
 *
 * @ingroup IO
 */

/**
 * @defgroup SERIAL_LLD Serial Low Level Driver Template
 * @brief @ref SERIAL low level driver template.
 * @details This file is a template for a serial low level driver.
 *
 * @ingroup SERIAL
 */