Hello i have tried to implement a simple UART interface, with the following code:
/*****************************************************************************
* University of Southern Denmark
* Embedded Programming (EMP)
*
* MODULENAME.: main.c
*
* PROJECT....: EMP
*
* DESCRIPTION: Assignment 4, main module. No main.h file.
*
* Change Log:
*****************************************************************************
* Date Id Change
* YYMMDD
* --------------------
* 290417 MoH Module created.
*
*****************************************************************************/
/***************************** Include files *******************************/
#include <stdint.h>
#include "glob_def.h"
#include "tm4c123gh6pm.h"
#include "emp_type.h"
#include "uart0.h"
// led lights
#define RESET_RGB 0x0E
#define GREEN 0b00000110
#define YELLOW 0b00001010
#define RED 0b00001100
#define LED_OFF 0b00001110
//functions
char ReadChar(void);
void PrintChar(char c);
void PrintString(char * string);
char c;
int main(void) {
// Enable the GPIO port that is used for the on-board LED.
//
SYSCTL_RCGC2_R = SYSCTL_RCGC2_GPIOA | SYSCTL_RCGC2_GPIOC | SYSCTL_RCGC2_GPIOD | SYSCTL_RCGC2_GPIOF;
SYSCTL_RCGC1_R |= 0x00000001;
//init_systick();
//
// Enable the GPIO pin for the LED (PF3). Set the direction as output, and
// enable the GPIO pin for digital function.
//
GPIO_PORTC_DIR_R = 0xF0;
GPIO_PORTC_DEN_R = 0xF0;
GPIO_PORTD_DIR_R = 0x4C;
GPIO_PORTD_DEN_R = 0x4C;
GPIO_PORTF_DIR_R = 0x0E;
GPIO_PORTF_DEN_R = 0x1F;
//inistialize the uart
uart0_init( 9600, 8, 1, 'n' );
while(1)
{
PrintString("Enter \"r\",\"g\", or \"y\":\n\r"); // show string
c = ReadChar();
PrintChar(c);
PrintString("\n\r");
switch(c) // show led color based on case
{
case 'r':
GPIO_PORTF_DATA_R &= ~(RESET_RGB);
GPIO_PORTF_DATA_R |= RED;
break;
case 'g':
GPIO_PORTF_DATA_R &= ~(RESET_RGB);
GPIO_PORTF_DATA_R |= GREEN;
break;
case 'y':
GPIO_PORTF_DATA_R &= ~(RESET_RGB);
GPIO_PORTF_DATA_R |= YELLOW;
break;
default:
GPIO_PORTF_DATA_R &= ~(RESET_RGB);
GPIO_PORTF_DATA_R |= LED_OFF;;
break;
}
}
}
void PrintChar(char c)
{
while(uart0_tx_rdy()!= 0);
uart0_putc(c);
}
char ReadChar(void)
{
char c;
while(uart0_rx_rdy()!=0);
uart0_getc();
}
void PrintString(char * string)
{
while(*string);
PrintChar(*(string++));
}
The functions GetChar an Printchar use functions from the following module:
/*****************************************************************************
* University of Southern Denmark
* Embedded Programming (EMP)
*
* MODULENAME.: emp.c
*
* PROJECT....: EMP
*
* DESCRIPTION: See module specification file (.h-file).
*
* Change Log:
*****************************************************************************
* Date Id Change
* YYMMDD
* --------------------
* 150228 MoH Module created.
*
*****************************************************************************/
/***************************** Include files *******************************/
#include <stdint.h>
#include "tm4c123gh6pm.h"
#include "emp_type.h"
/***************************** Defines *******************************/
/***************************** Constants *******************************/
/***************************** Variables *******************************/
char c;
/***************************** Functions *******************************/
INT32U lcrh_databits( INT8U antal_databits )
/*****************************************************************************
* Input :
* Output :
* Function : sets bit 5 and 6 according to the wanted number of data bits.
* 5: bit5 = 0, bit6 = 0.
* 6: bit5 = 1, bit6 = 0.
* 7: bit5 = 0, bit6 = 1.
* 8: bit5 = 1, bit6 = 1 (default).
* all other bits are returned = 0
******************************************************************************/
{
if(( antal_databits < 5 ) || ( antal_databits > 8 ))
antal_databits = 8;
return(( (INT32U)antal_databits - 5 ) << 5 ); // Control bit 5-6, WLEN
}
INT32U lcrh_stopbits( INT8U antal_stopbits )
/*****************************************************************************
* Input :
* Output :
* Function : sets bit 3 according to the wanted number of stop bits.
* 1 stpobit: bit3 = 0 (default).
* 2 stopbits: bit3 = 1.
* all other bits are returned = 0
******************************************************************************/
{
if( antal_stopbits == 2 )
return( 0x00000008 ); // return bit 3 = 1
else
return( 0x00000000 ); // return all zeros
}
INT32U lcrh_parity( INT8U parity )
/*****************************************************************************
* Input :
* Output :
* Function : sets bit 1, 2 and 7 to the wanted parity.
* 'e': 00000110b.
* 'o': 00000010b.
* '0': 10000110b.
* '1': 10000010b.
* 'n': 00000000b.
* all other bits are returned = 0
******************************************************************************/
{
INT32U result;
switch( parity )
{
case 'e':
result = 0x00000006;
break;
case 'o':
result = 0x00000002;
break;
case '0':
result = 0x00000086;
break;
case '1':
result = 0x00000082;
break;
case 'n':
/* no break */
default:
result = 0x00000000;
}
return( result );
}
void uart0_fifos_enable()
/*****************************************************************************
* Input :
* Output :
* Function : Enable the tx and rx fifos
******************************************************************************/
{
UART0_LCRH_R |= 0x00000010;
}
void uart0_fifos_disable()
/*****************************************************************************
* Input :
* Output :
* Function : Enable the tx and rx fifos
******************************************************************************/
{
UART0_LCRH_R &= 0xFFFFFFEF;
}
extern BOOLEAN uart0_rx_rdy()
/*****************************************************************************
* Function : See module specification (.h-file).
*****************************************************************************/
{
return( UART0_FR_R & UART_FR_RXFF );
}
extern INT8U uart0_getc()
/*****************************************************************************
* Function : See module specification (.h-file).
*****************************************************************************/
{
return ( UART0_DR_R );
}
extern BOOLEAN uart0_tx_rdy()
/*****************************************************************************
* Function : See module specification (.h-file).
*****************************************************************************/
{
return( UART0_FR_R & UART_FR_TXFE );
}
extern void uart0_putc( INT8U ch )
/*****************************************************************************
* Function : See module specification (.h-file).
*****************************************************************************/
{
UART0_DR_R = ch;
}
extern void uart0_init( INT32U baud_rate, INT8U databits, INT8U stopbits, INT8U parity )
/*****************************************************************************
* Function : See module specification (.h-file).
*****************************************************************************/
{
INT32U BRD;
#ifndef E_PORTA
#define E_PORTA
SYSCTL_RCGC2_R |= SYSCTL_RCGC2_GPIOA; // Enable clock for Port A
#endif
#ifndef E_UART0
#define E_UART0
SYSCTL_RCGC1_R |= SYSCTL_RCGC1_UART0; // Enable clock for UART 0
#endif
GPIO_PORTA_AFSEL_R |= 0x00000003; // set PA0 og PA1 to alternativ function (uart0)
GPIO_PORTA_DIR_R |= 0x00000002; // set PA1 (uart0 tx) to output
GPIO_PORTA_DIR_R &= 0xFFFFFFFE; // set PA0 (uart0 rx) to input
GPIO_PORTA_DEN_R |= 0x00000003; // enable digital operation of PA0 and PA1
GPIO_PORTA_PUR_R |= 0x00000002;
BRD = 64000000 / baud_rate; // X-sys*64/(16*baudrate) = 16M*4/baudrate
UART0_IBRD_R = BRD / 64;
UART0_FBRD_R = BRD & 0x0000003F;
UART0_LCRH_R = lcrh_databits( databits );
UART0_LCRH_R += lcrh_stopbits( stopbits );
UART0_LCRH_R += lcrh_parity( parity );
uart0_fifos_disable();
UART0_CTL_R |= (UART_CTL_UARTEN | UART_CTL_TXE ); // Enable UART
}
/****************************** End Of Module *******************************/
The code simply should show red, yellow or green based on the button i press on my keyboard.
I have no errors, but i get nothing through to the terminal i am using(putty). It's worth noting that i have tried other terminals as well.
