// ParallelPrinter.c
// Runs on LM3S811
// Use a handshaked interface to request a character print while
// outputting a parallel character and wait for a rising edge signaling
// completion.
// Daniel Valvano
// June 16, 2011

/* This example accompanies the book
   "Embedded Systems: Real Time Interfacing to the Arm Cortex M3",
   ISBN: 978-1463590154, Jonathan Valvano, copyright (c) 2011
   Program 4.8, Example 4.3, Figure 4.33, Section 4.8

 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/
 */

// "ready" signal connected to PC4 (rising edge means print complete)
// "start" signal connected to PC5 (rising edge starts printing)
// print character data bit 7 connected to PD7
// print character data bit 6 connected to PD6
// print character data bit 5 connected to PD5
// print character data bit 4 connected to PD4
// print character data bit 3 connected to PD3
// print character data bit 2 connected to PD2
// print character data bit 1 connected to PD1
// print character data bit 0 connected to PD0

#define GPIO_PORTC_DATA_R       (*((volatile unsigned long *)0x400063FC))
#define GPIO_PORTC_DIR_R        (*((volatile unsigned long *)0x40006400))
#define GPIO_PORTC_IEV_R        (*((volatile unsigned long *)0x4000640C))
#define GPIO_PORTC_RIS_R        (*((volatile unsigned long *)0x40006414))
#define GPIO_PORTC_ICR_R        (*((volatile unsigned long *)0x4000641C))
#define GPIO_PORTC_DEN_R        (*((volatile unsigned long *)0x4000651C))
#define GPIO_PORTC5             (*((volatile unsigned long *)0x40006080))
#define GPIO_PORTD_DATA_R       (*((volatile unsigned long *)0x400073FC))
#define GPIO_PORTD_DIR_R        (*((volatile unsigned long *)0x40007400))
#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 Printer_Init(void){
  volatile unsigned long delay;
  // activate port C and port D
  SYSCTL_RCGC2_R |= SYSCTL_RCGC2_GPIOC+SYSCTL_RCGC2_GPIOD;
  delay = SYSCTL_RCGC2_R;   // allow time to finish activating
  GPIO_PORTC5 = 0x20;       // Start=1
//  GPIO_PORTC_DATA_R |= 0x20;// Start=1
  GPIO_PORTC_DIR_R |= 0x20; // PC5=Start out
  GPIO_PORTC_DIR_R &= ~0x10;// PC4=Ready in
  GPIO_PORTC_DEN_R |= 0x30; // enable digital I/O on PC5-4
  GPIO_PORTD_DIR_R |= 0xFF; // make PD7-0 out (PD7-0 data)
  GPIO_PORTD_DEN_R |= 0xFF; // enable digital I/O on PD7-0
  GPIO_PORTC_IEV_R |= 0x10; // rise on PC4
  GPIO_PORTC_ICR_R = 0x10;  // clear flag4
}
void Printer_Out(unsigned char data){
  GPIO_PORTC_ICR_R = 0x10;          // clear flag4
  GPIO_PORTD_DATA_R &= ~0xFF;
  GPIO_PORTD_DATA_R += data&0xFF;   // write data
  GPIO_PORTC5 = 0x00;               // Start=0
//  GPIO_PORTC_DATA_R &= ~0x20;       // Start=0
  GPIO_PORTC5 = 0x20;               // Start=1
//  GPIO_PORTC_DATA_R |= 0x20;        // Start=1
  while((GPIO_PORTC_RIS_R&0x10)==0);// wait
}

//debug code
int main(void){
  Printer_Init();           // initialize ports
  while(1){
    Printer_Out('T');       // 'T' = 0x54
    Printer_Out('e');       // 'e' = 0x65
    Printer_Out('s');       // 's' = 0x73
    Printer_Out('t');       // 't' = 0x74
  }
}