//*****************************************************************************
//
// uart_polled.c - Example demonstrating UART polled I/O.
//
// Copyright (c) 2010-2011 Texas Instruments Incorporated. All rights reserved.
// Software License Agreement
//
// Texas Instruments (TI) is supplying this software for use solely and
// exclusively on TI's microcontroller products. The software is owned by
// TI and/or its suppliers, and is protected under applicable copyright
// laws. You may not combine this software with "viral" open-source
// software in order to form a larger program.
//
// THIS SOFTWARE IS PROVIDED "AS IS" AND WITH ALL FAULTS.
// 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. TI SHALL NOT, UNDER ANY
// CIRCUMSTANCES, BE LIABLE FOR SPECIAL, INCIDENTAL, OR CONSEQUENTIAL
// DAMAGES, FOR ANY REASON WHATSOEVER.
//
// This is part of revision 7243 of the Stellaris Firmware Development Package.
//
//*****************************************************************************
#include "inc/hw_memmap.h"
#include "inc/hw_types.h"
#include "driverlib/sysctl.h"
#include "driverlib/uart.h"
#include "driverlib/gpio.h"
//*****************************************************************************
//
//! \addtogroup uart_examples_list
//! <h1>UART Polled I/O (uart_polled)</h1>
//!
//! This example shows how to set up the UART and use polled I/O methods
//! for transmitting and receiving UART data. The example receives characters
//! from UART0 and retransmits the same character using UART0. It can be
//! tested by using a serial terminal program on a host computer. This
//! example will echo every character that is type until the return/enter key
//! is pressed.
//!
//! This example uses the following peripherals and I/O signals. You must
//! review these and change as needed for your own board:
//! - UART0 peripheral
//! - GPIO Port A peripheral (for UART0 pins)
//! - UART0RX - PA0
//! - UART0TX - PA1
//!
//
//*****************************************************************************
//*****************************************************************************
//
// Configure the UART and perform reads and writes using polled I/O.
//
//*****************************************************************************
int
main(void)
{
char cThisChar;
//
// Set the clocking to run directly from the external crystal/oscillator.
// TODO: The SYSCTL_XTAL_ value must be changed to match the value of the
// crystal on your board.
//
SysCtlClockSet(SYSCTL_SYSDIV_1 | SYSCTL_USE_OSC | SYSCTL_OSC_MAIN |
SYSCTL_XTAL_16MHZ);
//
// Enable the peripherals used by this example.
// The UART itself needs to be enabled, as well as the GPIO port
// containing the pins that will be used.
//
SysCtlPeripheralEnable(SYSCTL_PERIPH_UART0);
SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOA);
//
// Configure the GPIO pin muxing for the UART function.
// This is only necessary if your part supports GPIO pin function muxing.
// Study the data sheet to see which functions are allocated per pin.
// TODO: change this to select the port/pin you are using
//
GPIOPinConfigure(GPIO_PA0_U0RX);
GPIOPinConfigure(GPIO_PA1_U0TX);
//
// Since GPIO A0 and A1 are used for the UART function, they must be
// configured for use as a peripheral function (instead of GPIO).
// TODO: change this to match the port/pin you are using
//
GPIOPinTypeUART(GPIO_PORTA_BASE, GPIO_PIN_0 | GPIO_PIN_1);
//
// Configure the UART for 115,200, 8-N-1 operation.
// This function uses SysCtlClockGet() to get the system clock
// frequency. This could be also be a variable or hard coded value
// instead of a function call.
//
UARTConfigSetExpClk(UART0_BASE, SysCtlClockGet(), 115200,
(UART_CONFIG_WLEN_8 | UART_CONFIG_STOP_ONE |
UART_CONFIG_PAR_NONE));
//
// Put a character to show start of example. This will display on the
// terminal.
//
UARTCharPut(UART0_BASE, '!');
//
// Enter a loop to read characters from the UART, and write them back
// (echo). When a line end is received, the loop terminates.
//
do
{
//
// Read a character using the blocking read function. This function
// will not return until a character is available.
//
cThisChar = UARTCharGet(UART0_BASE);
//
// Write the same character using the blocking write function. This
// function will not return until there was space in the FIFO and
// the character is written.
//
UARTCharPut(UART0_BASE, cThisChar);
//
// Stay in the loop until either a CR or LF is received.
//
} while((cThisChar != '\n') && (cThisChar != '\r'));
//
// Put a character to show the end of the example. This will display on
// the terminal.
//
UARTCharPut(UART0_BASE, '@');
//
// Return no errors
//
return(0);
}
