//*****************************************************************************
//
// qei.c - Driver for the Quadrature Encoder with Index.
//
// Copyright (c) 2005,2006 Luminary Micro, Inc.  All rights reserved.
//
// Software License Agreement
//
// Luminary Micro, Inc. (LMI) is supplying this software for use solely and
// exclusively on LMI's Stellaris Family of microcontroller products.
//
// The software is owned by LMI and/or its suppliers, and is protected under
// applicable copyright laws.  All rights are reserved.  Any use in violation
// of the foregoing restrictions may subject the user to criminal sanctions
// under applicable laws, as well as to civil liability for the breach of the
// terms and conditions of this license.
//
// THIS SOFTWARE IS PROVIDED "AS IS".  NO WARRANTIES, WHETHER EXPRESS, IMPLIED
// OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE APPLY TO THIS SOFTWARE.
// LMI SHALL NOT, IN ANY CIRCUMSTANCES, BE LIABLE FOR SPECIAL, INCIDENTAL, OR
// CONSEQUENTIAL DAMAGES, FOR ANY REASON WHATSOEVER.
//
// This is part of revision 991 of the Stellaris Driver Library.
//
//*****************************************************************************

//*****************************************************************************
//
//! \addtogroup qei_api
//! @{
//
//*****************************************************************************

#include "../hw_ints.h"
#include "../hw_memmap.h"
#include "../hw_qei.h"
#include "../hw_types.h"
#include "debug.h"
#include "interrupt.h"
#include "qei.h"

//*****************************************************************************
//
//! Enables the quadrature encoder.
//!
//! \param ulBase is the base address of the quadrature encoder module.
//!
//! This will enable operation of the quadrature encoder module.  It must be
//! configured before it is enabled.
//!
//! \sa QEIConfigure()
//!
//! \return None.
//
//*****************************************************************************
#if defined(GROUP_enable) || defined(BUILD_ALL) || defined(DOXYGEN)
void
QEIEnable(unsigned long ulBase)
{
    //
    // Check the arguments.
    //
    ASSERT(ulBase == QEI_BASE);

    //
    // Enable the QEI module.
    //
    HWREG(ulBase + QEI_O_CTL) |= QEI_CTL_ENABLE;
}
#endif

//*****************************************************************************
//
//! Disables the quadrature encoder.
//!
//! \param ulBase is the base address of the quadrature encoder module.
//!
//! This will disable operation of the quadrature encoder module.
//!
//! \return None.
//
//*****************************************************************************
#if defined(GROUP_disable) || defined(BUILD_ALL) || defined(DOXYGEN)
void
QEIDisable(unsigned long ulBase)
{
    //
    // Check the arguments.
    //
    ASSERT(ulBase == QEI_BASE);

    //
    // Disable the QEI module.
    //
    HWREG(ulBase + QEI_O_CTL) &= ~(QEI_CTL_ENABLE);
}
#endif

//*****************************************************************************
//
//! Configures the quadrature encoder.
//!
//! \param ulBase is the base address of the quadrature encoder module.
//! \param ulConfig is the configuration for the quadrature encoder.  See below
//! for a description of this parameter.
//! \param ulMaxPosition specifies the maximum position value.
//!
//! This will configure the operation of the quadrature encoder.  The
//! \e ulConfig parameter provides the configuration of the encoder and is the
//! logical OR of several values:
//!
//! - \b QEI_CONFIG_CAPTURE_A or \b QEI_CONFIG_CAPTURE_A_B to specify if edges
//!   on channel A or on both channels A and B should be counted by the
//!   position integrator and velocity accumulator.
//! - \b QEI_CONFIG_NO_RESET or \b QEI_CONFIG_RESET_IDX to specify if the
//!   position integrator should be reset when the index pulse is detected.
//! - \b QEI_CONFIG_QUADRATURE or \b QEI_CONFIG_CLOCK_DIR to specify if
//!   quadrature signals are being provided on ChA and ChB, or if a direction
//!   signal and a clock are being provided instead.
//! - \b QEI_CONFIG_NO_SWAP or \b QEI_CONFIG_SWAP to specify if the signals
//!   provided on ChA and ChB should be swapped before being processed.
//!
//! \e ulMaxPosition is the maximum value of the position integrator, and is
//! the value used to reset the position capture when in index reset mode and
//! moving in the reverse (negative) direction.
//!
//! \return None.
//
//*****************************************************************************
#if defined(GROUP_configure) || defined(BUILD_ALL) || defined(DOXYGEN)
void
QEIConfigure(unsigned long ulBase, unsigned long ulConfig,
             unsigned long ulMaxPosition)
{
    //
    // Check the arguments.
    //
    ASSERT(ulBase == QEI_BASE);

    //
    // Write the new configuration to the hardware.
    //
    HWREG(ulBase + QEI_O_CTL) = ((HWREG(ulBase + QEI_O_CTL) &
                                  ~(QEI_CTL_CAPMODE | QEI_CTL_RESMODE |
                                    QEI_CTL_SIGMODE | QEI_CTL_SWAP)) |
                                 ulConfig);

    //
    // Set the maximum position.
    //
    HWREG(ulBase + QEI_O_MAXPOS) = ulMaxPosition;
}
#endif

//*****************************************************************************
//
//! Gets the current encoder position.
//!
//! \param ulBase is the base address of the quadrature encoder module.
//!
//! This returns the current position of the encoder.  Depending upon the
//! configuration of the encoder, and the incident of an index pulse, this
//! value may or may not contain the expected data (i.e. if in reset on index
//! mode, if an index pulse has not been encountered, the position counter will
//! not be aligned with the index pulse yet).
//!
//! \return The current position of the encoder.
//
//*****************************************************************************
#if defined(GROUP_positionget) || defined(BUILD_ALL) || defined(DOXYGEN)
unsigned long
QEIPositionGet(unsigned long ulBase)
{
    //
    // Check the arguments.
    //
    ASSERT(ulBase == QEI_BASE);

    //
    // Return the current position counter.
    //
    return(HWREG(ulBase + QEI_O_POS));
}
#endif

//*****************************************************************************
//
//! Sets the current encoder position.
//!
//! \param ulBase is the base address of the quadrature encoder module.
//! \param ulPosition is the new position for the encoder.
//!
//! This sets the current position of the encoder; the encoder position will
//! then be measured relative to this value.
//!
//! \return None.
//
//*****************************************************************************
#if defined(GROUP_positionset) || defined(BUILD_ALL) || defined(DOXYGEN)
void
QEIPositionSet(unsigned long ulBase, unsigned long ulPosition)
{
    //
    // Check the arguments.
    //
    ASSERT(ulBase == QEI_BASE);

    //
    // Set the position counter.
    //
    HWREG(ulBase + QEI_O_POS) = ulPosition;
}
#endif

//*****************************************************************************
//
//! Gets the current direction of rotation.
//!
//! \param ulBase is the base address of the quadrature encoder module.
//!
//! This returns the current direction of rotation.  In this case, current
//! means the most recently detected direction of the encoder; it may not be
//! presently moving but this is the direction it last moved before it stopped.
//!
//! \return 1 if moving in the forward direction or -1 if moving in the reverse
//! direction.
//
//*****************************************************************************
#if defined(GROUP_directionget) || defined(BUILD_ALL) || defined(DOXYGEN)
long
QEIDirectionGet(unsigned long ulBase)
{
    //
    // Check the arguments.
    //
    ASSERT(ulBase == QEI_BASE);

    //
    // Return the direction of rotation.
    //
    return((HWREG(ulBase + QEI_O_STAT) & QEI_STAT_DIRECTION) ? -1 : 1);
}
#endif

//*****************************************************************************
//
//! Gets the encoder error indicator.
//!
//! \param ulBase is the base address of the quadrature encoder module.
//!
//! This returns the error indicator for the quadrature encoder.  It is an
//! error for both of the signals of the quadrature input to change at the same
//! time.
//!
//! \return true if an error has occurred and false otherwise.
//
//*****************************************************************************
#if defined(GROUP_errorget) || defined(BUILD_ALL) || defined(DOXYGEN)
tBoolean
QEIErrorGet(unsigned long ulBase)
{
    //
    // Check the arguments.
    //
    ASSERT(ulBase == QEI_BASE);

    //
    // Return the error indicator.
    //
    return((HWREG(ulBase + QEI_O_STAT) & QEI_STAT_ERROR) ? true : false);
}
#endif

//*****************************************************************************
//
//! Enables the velocity capture.
//!
//! \param ulBase is the base address of the quadrature encoder module.
//!
//! This will enable operation of the velocity capture in the quadrature
//! encoder module.  It must be configured before it is enabled.  Velocity
//! capture will not occur if the quadrature encoder is not enabled.
//!
//! \sa QEIVelocityConfigure() and QEIEnable()
//!
//! \return None.
//
//*****************************************************************************
#if defined(GROUP_velocityenable) || defined(BUILD_ALL) || defined(DOXYGEN)
void
QEIVelocityEnable(unsigned long ulBase)
{
    //
    // Check the arguments.
    //
    ASSERT(ulBase == QEI_BASE);

    //
    // Enable the velocity capture.
    //
    HWREG(ulBase + QEI_O_CTL) |= QEI_CTL_VELEN;
}
#endif

//*****************************************************************************
//
//! Disables the velocity capture.
//!
//! \param ulBase is the base address of the quadrature encoder module.
//!
//! This will disable operation of the velocity capture in the quadrature
//! encoder module.
//!
//! \return None.
//