4 : Using serial communication on LaunchPad

 

/*
 * Stellaris LAUNCHPAD LM4F120H5QR
 * Using UART to write a string into the Serial Monitor without using interrupts
 * Add the following to Pre-define NAME tab in the predefined Symbols in the Advanced Options
 * of the ARM compiler in the CCS Build in the project properties
 * --->  PART_LM4F120H5QR  <---
 */
#include <inc/hw_memmap.h>
#include <inc/hw_types.h>
#include <driverlib/gpio.h>
#include <driverlib/sysctl.h>
#include <driverlib/uart.h>
#include  <utils/uartstdio.c>

void blinkled(void)
{
	GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_1, 2);
	SysCtlDelay(200000);
	GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_1, 0);
}
int main(void)
{
	/*
	 * The System clock is run using a 16 Mhz crystal connected to the main oscillator pins of the microcontroller
	 * This generates a internal clock signal of 400 Mhz using the PLL
	 * The signal is prescaled by the system by 2
	 * Now we are defining a prescale of 5 in addition to make the clock frequency 40MHz
	 * The system clock frequency must be less than or equal to 80MHz
	 */
	SysCtlClockSet(SYSCTL_SYSDIV_5|SYSCTL_USE_PLL|SYSCTL_XTAL_16MHZ|SYSCTL_OSC_MAIN);
	/*
	 * Peripherals are enabled with this function.
	 *  At power-up, all peripherals are disabled.
	 *  System Clock to the peripheral must be enabled in order to use ADC
	 */
	SysCtlPeripheralEnable(SYSCTL_PERIPH_UART0);
	SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOA); // As GPIO Pins A0 and A1 are multiplexed with U0RX and U0TX
	SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOF);
	//Configuring the LED as output
	GPIOPinTypeGPIOOutput(GPIO_PORTF_BASE, GPIO_PIN_1);
	//Configuring the GPIO A0 and A1 for UART functionality
	GPIOPinConfigure(GPIO_PA0_U0RX);
	GPIOPinConfigure(GPIO_PA1_U0TX);

	GPIOPinTypeUART(GPIO_PORTA_BASE, GPIO_PIN_0|GPIO_PIN_1);
	IntEnable(INT_UART0);
	UARTIntEnable(UART0_BASE, UART_INT_RX | UART_INT_RT);
	UARTConfigSetExpClk(UART0_BASE, SysCtlClockGet(), 115200, UART_CONFIG_WLEN_8|UART_CONFIG_PAR_NONE|UART_CONFIG_STOP_ONE);
	/*
	 * Configures the UART to use the current system clock
	 * Sets the baud rate to 115200 and enables an 8bit no parity one stop bit communication(8-N-1)
	 */

	while(1)
	{

		unsigned char *buf = "Aravind RIG\n\r";
		//Waits until the UART is Ready
		while(UARTBusy(UART0_BASE));
		while(*buf != '\0')
			//Put the string character by character into the FIFO for transmission
			UARTCharPut(UART0_BASE, *buf++);
		blinkled();//blink led to denote a transmission
		SysCtlDelay(SysCtlClockGet()/2);//wait for a while
	}
}

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