UART.c

// UART.c
// Runs on LM3S811, LM3S1968, LM3S8962, LM4F120
// Simple device driver for the UART.  This version of the UART
// driver uses UART1 instead of UART0 and has fewer character
// I/O functions compared to the example project UART_4F120.
// Daniel Valvano
// August 1, 2013
// Modified by EE345L students Charlie Gough && Matt Hawk
// Modified by EE345M students Agustinus Darmawan && Mingjie Qiu

/* This example accompanies the book
   "Embedded Systems: Real Time Interfacing to Arm Cortex M Microcontrollers",
   ISBN: 978-1463590154, Jonathan Valvano, copyright (c) 2013
   Program 4.12, Section 4.9.4, Figures 4.26 and 4.40

 Copyright 2013 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/
 */

// U1Rx connected to PC4
// U1Tx connected to PC5

#include "UART.h"

#define GPIO_PORTC_AFSEL_R      (*((volatile unsigned long *)0x40006420))
#define GPIO_PORTC_DEN_R        (*((volatile unsigned long *)0x4000651C))
#define GPIO_PORTC_AMSEL_R      (*((volatile unsigned long *)0x40006528))
#define GPIO_PORTC_PCTL_R       (*((volatile unsigned long *)0x4000652C))
#define UART1_DR_R              (*((volatile unsigned long *)0x4000D000))
#define UART1_FR_R              (*((volatile unsigned long *)0x4000D018))
#define UART1_IBRD_R            (*((volatile unsigned long *)0x4000D024))
#define UART1_FBRD_R            (*((volatile unsigned long *)0x4000D028))
#define UART1_LCRH_R            (*((volatile unsigned long *)0x4000D02C))
#define UART1_CTL_R             (*((volatile unsigned long *)0x4000D030))
#define UART_FR_TXFF            0x00000020  // UART Transmit FIFO Full
#define UART_FR_RXFE            0x00000010  // UART Receive FIFO Empty
#define UART_LCRH_WLEN_8        0x00000060  // 8 bit word length
#define UART_LCRH_FEN           0x00000010  // UART Enable FIFOs
#define UART_CTL_UARTEN         0x00000001  // UART Enable
#define SYSCTL_RCGC1_R          (*((volatile unsigned long *)0x400FE104))
#define SYSCTL_RCGC2_R          (*((volatile unsigned long *)0x400FE108))
#define SYSCTL_RCGC1_UART1      0x00000002  // UART1 Clock Gating Control
#define SYSCTL_RCGC2_GPIOC      0x00000004  // port C Clock Gating Control

//------------UART_Init------------
// Initialize the UART for 115,200 baud rate (assuming 80 MHz UART clock),
// 8 bit word length, no parity bits, one stop bit, FIFOs enabled
// Input: none
// Output: none
void UART1_Init(void){
  SYSCTL_RCGC1_R |= SYSCTL_RCGC1_UART1; // activate UART1
  SYSCTL_RCGC2_R |= SYSCTL_RCGC2_GPIOC; // activate port C
  UART1_CTL_R &= ~UART_CTL_UARTEN;      // disable UART
  UART1_IBRD_R = 43;  // 80,000,000/(16*115,200)) = 43.40278
  UART1_FBRD_R = 26;  //6-bbit fraction, round(0.40278 * 64) = 26
                                        // 8 bit word length (no parity bits, one stop bit, FIFOs)
  UART1_LCRH_R = (UART_LCRH_WLEN_8|UART_LCRH_FEN);
  UART1_CTL_R |= UART_CTL_UARTEN;       // enable UART
  GPIO_PORTC_AFSEL_R |= 0x30;           // enable alt funct on PC5-4
  GPIO_PORTC_DEN_R |= 0x30;             // enable digital I/O on PC5-4
                                        // configure PC5-4 as UART1
  GPIO_PORTC_PCTL_R = (GPIO_PORTC_PCTL_R&0xFF00FFFF)+0x00220000;
  GPIO_PORTC_AMSEL_R &= ~0x30;          // disable analog functionality on PC5-4
}

//------------UART_InChar------------
// Wait for new serial port input
// Input: none
// Output: ASCII code for key typed
unsigned char UART1_InChar(void){
  while((UART1_FR_R&UART_FR_RXFE) != 0);
  return((unsigned char)(UART1_DR_R&0xFF));
}

//------------UART_InCharNonBlocking------------
// Get oldest serial port input and return immediately
// if there is no data.
// Input: none
// Output: ASCII code for key typed or 0 if no character
unsigned char UART1_InCharNonBlocking(void){
  if((UART1_FR_R&UART_FR_RXFE) == 0){
    return((unsigned char)(UART1_DR_R&0xFF));
  } else{
    return 0;
  }
}

//------------UART_OutChar------------
// Output 8-bit to serial port
// Input: letter is an 8-bit ASCII character to be transferred
// Output: none
void UART1_OutChar(unsigned char data){
  while((UART1_FR_R&UART_FR_TXFF) != 0);
  UART1_DR_R = data;
}