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// TuningFork.c Lab 12
// Runs on LM4F120/TM4C123
// Use SysTick interrupts to create a squarewave at 440Hz.  
// There is a positive logic switch connected to PA3, PB3, or PE3.
// There is an output on PA2, PB2, or PE2. The output is 
//   connected to headphones through a 1k resistor.
// The volume-limiting resistor can be any value from 680 to 2000 ohms
// The tone is initially off, when the switch goes from
// not touched to touched, the tone toggles on/off.
//                   |---------|               |---------|     
// Switch   ---------|         |---------------|         |------
//
//                    |-| |-| |-| |-| |-| |-| |-|
// Tone     ----------| |-| |-| |-| |-| |-| |-| |---------------
//
// Daniel Valvano, Jonathan Valvano
// January 15, 2016

/* This example accompanies the book
   "Embedded Systems: Introduction to ARM Cortex M Microcontrollers",
   ISBN: 978-1469998749, Jonathan Valvano, copyright (c) 2015

 Copyright 2016 by Jonathan W. Valvano, valvano@mail.utexas.edu
    You may use, edit, run or distribute this file
    as long as the above copyright notice remains
 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.
 VALVANO SHALL NOT, IN ANY CIRCUMSTANCES, BE LIABLE FOR SPECIAL, INCIDENTAL,
 OR CONSEQUENTIAL DAMAGES, FOR ANY REASON WHATSOEVER.
 For more information about my classes, my research, and my books, see
 http://users.ece.utexas.edu/~valvano/
 */

#include "TExaS.h"

#include "..//tm4c123gh6pm.h"


// basic functions defined at end of startup.s
void DisableInterrupts(void); // Disable interrupts
void EnableInterrupts(void); // Enable interrupts
void WaitForInterrupt(void); // low power mode

// here I defined my global variables

unsigned long Switch = 0;
unsigned char lastSwitch = 0;
unsigned char doToggle = 0;

// input from PA3, output from PA2, SysTick interrupts
void Sound_Init(void) {
  unsigned long volatile delay;

  SYSCTL_RCGC2_R |= 0x01;
  delay = SYSCTL_RCGC2_R;
  GPIO_PORTA_DEN_R &= ~0x08;
  GPIO_PORTA_DIR_R &= ~0x08; // MAKE PA2 A OUTPUT
  GPIO_PORTA_DIR_R |= 0x04; // MAKE PA3 A INPUT
  GPIO_PORTA_AFSEL_R &= ~0x08; //DIASBLE ALT FUNCTION ON PA2 AND PA3
  GPIO_PORTA_AFSEL_R &= ~0x04;
  GPIO_PORTA_DEN_R |= 0x0C; // ENABLE DIGITAL I/O ON PA2 AND PA3
  GPIO_PORTA_AMSEL_R &= ~0x08; /// DISABLE ANALOG FUNCTIONALITY OF PA
  GPIO_PORTA_AMSEL_R &= ~0x04;
  GPIO_PORTA_PCTL_R &= ~0x0000FF00;
  NVIC_ST_CTRL_R = 0; // disable SysTick during setup
  NVIC_ST_RELOAD_R = 90908; // reload value
  NVIC_ST_CURRENT_R = 0; // any write to current clears it
  NVIC_SYS_PRI3_R = (NVIC_SYS_PRI3_R & 0x00FFFFFF) | 0x40000000;
  NVIC_ST_CTRL_R = 0x07;
  EnableInterrupts();
}

// 880 Hz
void SysTick_Handler(void) {
  if (doToggle)
    GPIO_PORTA_DATA_R ^= 0x04; // toggle PA2 tone
  else
    GPIO_PORTA_DATA_R &= ~0x04; //make PA2 low - tone off
}

int main(void) { // activate grader and set system clock to 80 MHz

  TExaS_Init(SW_PIN_PA3, HEADPHONE_PIN_PA2, ScopeOn);
  Sound_Init();
  EnableInterrupts(); // enable after all initialization are done
  while (1) {
    Switch = (GPIO_PORTA_DATA_R & 0x08); // get PA3 (switch state)
    if (Switch == 0x08 && lastSwitch == 0) { // true if rising edge
      doToggle = !doToggle;
    }
    lastSwitch = Switch;
  }

}