// TwoButtonVector.c
// Runs on LM3S811
// Use vectored interrupts to respond to two button presses.  Note
// that button bouncing is not addressed.
// Daniel Valvano
// June 24, 2011

/* This example accompanies the book
   "Embedded Systems: Real Time Interfacing to the Arm Cortex M3",
   ISBN: 978-1463590154, Jonathan Valvano, copyright (c) 2011
   Example 5.1, Program 5.7

 Copyright 2011 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/
 */

// user button connected to PC4 (trigger on falling edge)
// momentary, negative logic button connected to PD4 (trigger on falling edge)

#define NVIC_EN0_INT2           0x00000004  // Interrupt 2 enable
#define NVIC_EN0_INT3           0x00000008  // Interrupt 3 enable
#define NVIC_EN0_R              (*((volatile unsigned long *)0xE000E100))  // IRQ 0 to 31 Set Enable Register
#define NVIC_PRI0_R             (*((volatile unsigned long *)0xE000E400))  // IRQ 0 to 3 Priority Register
#define GPIO_PORTC_DIR_R        (*((volatile unsigned long *)0x40006400))
#define GPIO_PORTC_IS_R         (*((volatile unsigned long *)0x40006404))
#define GPIO_PORTC_IBE_R        (*((volatile unsigned long *)0x40006408))
#define GPIO_PORTC_IEV_R        (*((volatile unsigned long *)0x4000640C))
#define GPIO_PORTC_IM_R         (*((volatile unsigned long *)0x40006410))
#define GPIO_PORTC_ICR_R        (*((volatile unsigned long *)0x4000641C))
#define GPIO_PORTC_DEN_R        (*((volatile unsigned long *)0x4000651C))
#define GPIO_PORTD_DIR_R        (*((volatile unsigned long *)0x40007400))
#define GPIO_PORTD_IS_R         (*((volatile unsigned long *)0x40007404))
#define GPIO_PORTD_IBE_R        (*((volatile unsigned long *)0x40007408))
#define GPIO_PORTD_IEV_R        (*((volatile unsigned long *)0x4000740C))
#define GPIO_PORTD_IM_R         (*((volatile unsigned long *)0x40007410))
#define GPIO_PORTD_ICR_R        (*((volatile unsigned long *)0x4000741C))
#define GPIO_PORTD_DEN_R        (*((volatile unsigned long *)0x4000751C))
#define SYSCTL_RCGC2_R          (*((volatile unsigned long *)0x400FE108))
#define SYSCTL_RCGC2_GPIOD      0x00000008  // port D Clock Gating Control
#define SYSCTL_RCGC2_GPIOC      0x00000004  // port C Clock Gating Control

void DisableInterrupts(void); // Disable interrupts
void EnableInterrupts(void);  // Enable interrupts
long StartCritical (void);    // previous I bit, disable interrupts
void EndCritical(long sr);    // restore I bit to previous value
void WaitForInterrupt(void);  // low power mode

// global variables visible in Watch window of debugger
// set when corresponding button pressed
volatile unsigned char SW1, SW2;
void VectorButtons_Init(void){
  // activate port C and port D
  SYSCTL_RCGC2_R |= SYSCTL_RCGC2_GPIOC+SYSCTL_RCGC2_GPIOD;
  SW1 = 0;                    // clear semaphores
  SW2 = 0;
  GPIO_PORTC_DIR_R &= ~0x10;  // make PC4 in (PC4 built-in button)
  GPIO_PORTC_DEN_R |= 0x10;   // enable digital I/O on PC4
  GPIO_PORTC_IS_R &= ~0x10;   // PC4 is edge-sensitive (default setting)
  GPIO_PORTC_IBE_R &= ~0x10;  // PC4 is not both edges (default setting)
  GPIO_PORTC_IEV_R &= ~0x10;  // PC4 falling edge event (default setting)
  GPIO_PORTC_ICR_R = 0x10;    // clear flag4
  GPIO_PORTC_IM_R |= 0x10;    // enable interrupt on PC4
                              // GPIO PortC=priority 2
  NVIC_PRI0_R = (NVIC_PRI0_R&0xFF00FFFF)|0x00400000; // bits 21-23
  GPIO_PORTD_DIR_R &= ~0x10;  // make PD4 in (PD4 button)
  GPIO_PORTD_DEN_R |= 0x10;   // enable digital I/O on PD4
  GPIO_PORTD_IS_R &= ~0x10;   // PD4 is edge-sensitive (default setting)
  GPIO_PORTD_IBE_R &= ~0x10;  // PD4 is not both edges (default setting)
  GPIO_PORTD_IEV_R &= ~0x10;  // PD4 falling edge event (default setting)
  GPIO_PORTD_ICR_R = 0x10;    // clear flag4
  GPIO_PORTD_IM_R |= 0x10;    // enable interrupt on PD4
                              // GPIO PortD=priority 2
  NVIC_PRI0_R = (NVIC_PRI0_R&0x00FFFFFF)|0x40000000; // bits 29-31
                              // enable interrupts 2 and 3 in NVIC
  NVIC_EN0_R |= (NVIC_EN0_INT2+NVIC_EN0_INT3);
  EnableInterrupts();
}
void GPIOPortC_Handler(void){
  GPIO_PORTC_ICR_R = 0x10;    // acknowledge flag4
  SW1 = 1;                    // signal SW1 occurred
}
void GPIOPortD_Handler(void){
  GPIO_PORTD_ICR_R = 0x10;    // acknowledge flag4
  SW2 = 1;                    // signal SW2 occurred
}

//debug code
int main(void){
  VectorButtons_Init();       // initialize interrupts and ports
  while(1){
    WaitForInterrupt();
  }
}