//*****************************************************************************
//
// switches.c - Routines for handling the switches on the CNC machine.
//
// Copyright (c) 2006-2007 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 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 220 of sw01246.
//
//*****************************************************************************

#include "hw_ints.h"
#include "hw_memmap.h"
#include "hw_types.h"
#include "gpio.h"
#include "interrupt.h"
#include "draw.h"
#include "switches.h"
#include "table.h"
#include "tool.h"

//*****************************************************************************
//
//! \page main_switches_intro Introduction
//!
//! There are seven switches on the CNC machine.  Six are limit switches, two
//! per axis, with one being the home limit switch (to indicate that the axis
//! is in the home position) and the other being a limit switch (to indicate
//! that the axis is at the extent of its travel).  The seventh switch is a
//! panic switch that causes all power to the machine (but not controller) to
//! be interrupted.
//!
//! The limit switches are wired up with two switches per GPIO pin; each switch
//! has a different resistor value and for part of an RC circuit.  The paired
//! limit switches can be read as a normal GPIO, providing no means of
//! distingishing between the two.  For normal operation of the CNC machine,
//! this is adequate.
//!
//! Alternatively, the charge time of the capacitor can be measured by sampling
//! the switch GPIO and used to determine which switch is engaged.  This is
//! used during the homing operation since the CNC machine needs to move the
//! gantry such that the home limit switch is engaged, not the limit switch.
//!
//! The panic switch is wired up like a normal switch.  When the panic switch
//! is engaged, an emergency stop of all mechanical systems on the CNC machine
//! must be performed as a safety measure.  After the panic switch is
//! disengaged, the table must undergo another homing operation to restore the
//! positional knowledge of the table.
//!
//! The code for handling the switches is contained in
//! <tt>main_micro/switches.c</tt>, with <tt>main_micro/switches.h</tt>
//! containing the API definitions for use by the remainder of the application.
//
//*****************************************************************************

//*****************************************************************************
//
//! \defgroup main_switches_api Definitions
//! @{
//
//*****************************************************************************

//*****************************************************************************
//
//! The GPIO pin on port C to which the X limit switches are connected.
//
//*****************************************************************************
#define LIMIT_X                 GPIO_PIN_2

//*****************************************************************************
//
//! The GPIO pin on port C to which the Y limit switches are connected.
//
//*****************************************************************************
#define LIMIT_Y                 GPIO_PIN_3

//*****************************************************************************
//
//! The GPIO pin on port C to which the Z limit switches are connected.
//
//*****************************************************************************
#define LIMIT_Z                 GPIO_PIN_4

//*****************************************************************************
//
//! The GPIO pin on port E to which the panic switch is connected.
//
//*****************************************************************************
#define SHUTDOWN                GPIO_PIN_2

//*****************************************************************************
//
//! Provide a small delay.
//!
//! \param ulCount is the number of delay loop iterations to perform.
//!
//! Delay for a fixed period of time while the capacitor in the limit switch
//! RC circuit is discharged.  It is written in assembly to keep the delay
//! consistent across tool chains, avoiding the need to tune the delay based on
//! the tool chain in use.
//!
//! \return None.
//
//*****************************************************************************
#if defined(ewarm)
static void
SwitchesDelay(unsigned long ulCount)
{
    __asm("    subs    r0, #1\n"
          "    bne     SwitchesDelay\n"
          "    bx      lr");
}
#endif
#if defined(gcc)
static void __attribute__((naked))
SwitchesDelay(unsigned long ulCount)
{
    __asm("    subs    r0, #1\n"
          "    bne     SwitchesDelay\n"
          "    bx      lr");
}
#endif
#if defined(rvmdk) || defined(__ARMCC_VERSION)
__asm void
SwitchesDelay(unsigned long ulCount)
{
    subs    r0, #1;
    bne     SwitchesDelay;
    bx      lr;
}
#endif

//*****************************************************************************
//
//! Interrupt handler for the shutdown switch interrupt.
//!
//! This is the interrupt handler that is called when the shutdown switch is
//! pressed.
//!
//! \return None.
//
//*****************************************************************************
void
GPIOEIntHandler(void)
{
    //
    // Clear the shutdown switch interrupt.
    //
    GPIOPinIntClear(GPIO_PORTE_BASE, SHUTDOWN);

    //
    // Turn off the tool.
    //
    ToolOff();

    //
    // Immediately stop the motion on all axes.
    //
    TableEmergencyStop();

    //
    // Stop the drawing operation (if any).
    //
    DrawStop();
}

//*****************************************************************************
//
//! Read the state of the switches.
//!
//! This function reads the state of the switches on the CNC machine.  The
//! limit switches are read as a simple GPIO; therefore the min and max limit
//! on each switch pin can not be distinguished.
//!
//! \return A bit field of \b SWITCH_??? values to indicate the switches that
//! are currently pressed.
//
//*****************************************************************************
unsigned long
SwitchesRead(void)
{
    unsigned long ulFlags, ulReg;

    //
    // Set the flags to indicate no buttons are pressed.
    //
    ulFlags = 0;

    //
    // Read the X, Y, and Z limit switches.
    //
    ulReg = GPIOPinRead(GPIO_PORTC_BASE, LIMIT_X | LIMIT_Y | LIMIT_Z);

    //
    // Set the X min and max limit flags if one of the X limit switches are
    // pressed.  Both flags are set since this does not distinguish which of
    // the two X limit switches are being pressed.
    //
    if(ulReg & LIMIT_X)
    {
        ulFlags |= SWITCH_LIMIT_X;
    }

    //
    // Set the Y min and max limit flags if one of the Y limit switches are
    // pressed.  Both flags are set since this does not distinguish which of
    // the two Y limit switches are being pressed.
    //
    if(ulReg & LIMIT_Y)
    {
        ulFlags |= SWITCH_LIMIT_Y;
    }

    //
    // Set the Z min and max limit flags if one of the Z limit switches are
    // pressed.  Both flags are set since this does not distinguish which of
    // the two Z limit switches are being pressed.
    //
    if(ulReg & LIMIT_Z)
    {
        ulFlags |= SWITCH_LIMIT_Z;
    }

    //
    // Read the shutdown switch.
    //
    ulReg = GPIOPinRead(GPIO_PORTE_BASE, SHUTDOWN);

    //