Problem while reading the UART in Tiva C series MCU

Hello Sreeni

The FIFO is 8 locations deep. Since you are able to receive 16-bytes it would mean that there is nothing wrong in the FIFO. For checking why the remaining bytes are not being received, can you put a blocking read condition such that till all expected number of bytes are not received the CPU remains in a while loop.

Also a code post would be useful to see how the data is being read.

Regards

Amit

Hi Amit,

Thanks for earliest reply..

I am using Keil as my IDE and the I got the libraries from TI web sight. 

My UART initialization is as below:

void UART_INIT (void)
{
static int i;
//Data1[30];

SysCtlPeripheralEnable(SYSCTL_PERIPH_UART1);
SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOC);
SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOA);// To enable the CDMA modem

GPIOPinConfigure(GPIO_PC4_U1RX);
GPIOPinConfigure(GPIO_PC5_U1TX);

GPIOPinTypeUART(GPIO_PORTC_BASE, 0x30);
GPIOPinTypeGPIOOutput(GPIO_PORTA_BASE, 0x40);

//UARTClockSourceSet(UART1_BASE, UART_CLOCK_PIOSC);

UARTConfigSetExpClk(UART1_BASE, SysCtlClockGet(), 115200,(UART_CONFIG_WLEN_8 | UART_CONFIG_STOP_ONE |UART_CONFIG_PAR_NONE));

// Enable the UART.
UARTEnable(UART1_BASE);

/*Turn ON the PA6*/
GPIOPinWrite(GPIO_PORTA_BASE, 0x40,0x40);
for(i = 0; i <= 100000; i++);
/*Turn OFF the PA6*/
GPIOPinWrite(GPIO_PORTA_BASE, 0x40,0);
for(i = 0; i <= 500000; i++);

and below is my code to receive the response.

while(UARTCharsAvail(UART1_BASE) != FALSE){

DataBuffer[i] = UARTCharGetNonBlocking(UART1_BASE);

i++;

}

Thanks 

Sreenivasa S

Hello Sreenivas,

Change the loop as below to see if all bytes are being recieved

while(i != CHAR_COUNT){

DataBuffer[i] = UARTCharGet(UART1_BASE);

i++;

}

Regards

Amit

Hi Amit,

I tried like this earlier and also now I put CHAR_COUNT =50 and tried,

but after I read 16 bytes of data it is get stuck in the below while loop to check the availability of char.

// Wait until a char is available.
//
while(HWREG(ui32Base + UART_O_FR) & UART_FR_RXFE)
{
}

and it will never come out of this loop.

Thanks

sreenivasa

Hi Amith,

Apart from our own board, I tried in stellaris launch pad. There I am losing some data...

my code is as follows

char get_char[38]; // global declaration

int main(void) {

int i,j;

static char send[38] = "Dexcel Electronics Designs Pvt Ltd...";

SysCtlClockSet(SYSCTL_SYSDIV_4 | SYSCTL_USE_OSC | SYSCTL_USE_PLL | SYSCTL_OSC_MAIN | SYSCTL_XTAL_16_3MHZ);

SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOC);

SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOE);
SysCtlPeripheralEnable(SYSCTL_PERIPH_UART4);

SysCtlPeripheralEnable(SYSCTL_PERIPH_UART5);

GPIOPinConfigure(GPIO_PC4_U4RX);

GPIOPinConfigure(GPIO_PE4_U5RX);
GPIOPinConfigure(GPIO_PC5_U4TX);

GPIOPinConfigure(GPIO_PE5_U5TX);

GPIOPinTypeUART(GPIO_PORTC_BASE, GPIO_PIN_4 | GPIO_PIN_5);
GPIOPinTypeUART(GPIO_PORTE_BASE, GPIO_PIN_4 | GPIO_PIN_5);

UARTConfigSetExpClk(UART4_BASE, SysCtlClockGet(), 115200,(UART_CONFIG_WLEN_8 | UART_CONFIG_STOP_ONE |UART_CONFIG_PAR_NONE));

UARTConfigSetExpClk(UART5_BASE, SysCtlClockGet(), 115200,(UART_CONFIG_WLEN_8 | UART_CONFIG_STOP_ONE |UART_CONFIG_PAR_NONE));

UARTEnable(UART4_BASE); UARTEnable(UART5_BASE);

i = 0;

while(send[i] != '\0')
{
UARTCharPut(UART4_BASE, send[i]);
i++;
}

i = 0;

while(send[i] != '\0')

{
get_char[i] = UARTCharGet(UART5_BASE);
i++;
}

while(1);

}

Please help me..

OUTPUT:

1) For 115200 baud rate - get_char contains "Dexcel Electroniesigns Pvt Ltd..." // missing chars - "cs D"

1) For 9600 baud rate - get_char contains "Dexcel ElectroniDesigns Pvt Ltd..." // missing chars - "cs "

Hello Sreeni,

Try the following change

while(send[i] != '\0')
{
UARTCharPut(UART4_BASE, send[i]);
get_char[i] = UARTCharGet(UART5_BASE);
i++;
}

Regards

Amit

Hi Amith,

Thanks for solution. It works fine now....

So should not put any delay in between send and receive I guess...

But in our board I cant able to get it....Anyway I have some other work to be done at priority after that I will look into this..

Thanks

Sreenivasa S 

Hello Sreeni,

My point is that there is a Overrun Interrupt happening. You can always check the UARTFR register to see if Overrun Flag is set or not. The same is available along with other flags in the UARTDR register from bits 8 to 11.

Regards

Amit

Hi Amit, 

I`m sorry if i`m posting this in the wrong place. 

But i`m getting the same problem as Sreeni first described. I´m not being able to read more than 16 bits. As you said, i paid attention to the registers and indeed:

UART_RIS_OERIS 1 UART Overrun Error Raw Interrupt Status

So how can I solve this issue?

Here is the code:

#include <stdint.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include "inc/hw_types.h"
#include "inc/hw_memmap.h"
#include "driverlib/sysctl.h"
#include "driverlib/gpio.h"
#include "driverlib/pin_map.h"
#include "driverlib/uart.h"

int main(void){
	SysCtlClockSet(SYSCTL_SYSDIV_5|SYSCTL_USE_PLL|SYSCTL_XTAL_16MHZ|SYSCTL_OSC_MAIN);

	SysCtlPeripheralEnable(SYSCTL_PERIPH_UART0);
	SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOA);
	SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOF);

	GPIOPinTypeGPIOOutput(GPIO_PORTF_BASE, GPIO_PIN_1|GPIO_PIN_2|GPIO_PIN_3);

	GPIOPinConfigure(GPIO_PA0_U0RX);
	GPIOPinConfigure(GPIO_PA1_U0TX);

	GPIOPinTypeUART(GPIO_PORTA_BASE, GPIO_PIN_0|GPIO_PIN_1);
	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);
	int i = 0;
	char str[32];
	while(1){
		while(UARTCharsAvail(UART0_BASE)){
			str[i] = UARTCharGet(UART0_BASE);
			i++;
			SysCtlDelay(900000);
			GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_1, 2);
			SysCtlDelay(900000);
			GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_1, 0);
			}
		i = 0;
	}
}

Best regards

Adriano

Hello Amit,

That's not all of the code. After that i'll just analyse the string and execute some functions that aren't written yet.  Here is the code:

#include <stdint.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include "inc/hw_types.h"
#include "inc/hw_memmap.h"
#include "driverlib/sysctl.h"
#include "driverlib/gpio.h"
#include "driverlib/pin_map.h"
#include "driverlib/uart.h"

int main(void){
	SysCtlClockSet(SYSCTL_SYSDIV_5|SYSCTL_USE_PLL|SYSCTL_XTAL_16MHZ|SYSCTL_OSC_MAIN);

	SysCtlPeripheralEnable(SYSCTL_PERIPH_UART0);
	SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOA);
	SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOF);

	GPIOPinTypeGPIOOutput(GPIO_PORTF_BASE, GPIO_PIN_1|GPIO_PIN_2|GPIO_PIN_3);

	GPIOPinConfigure(GPIO_PA0_U0RX);
	GPIOPinConfigure(GPIO_PA1_U0TX);

	GPIOPinTypeUART(GPIO_PORTA_BASE, GPIO_PIN_0|GPIO_PIN_1);
	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);
	int i = 0, k, xrml, yrml, irml;
	float x, y, z, f, s;
	char str[32];
	while(1){
		while(UARTCharsAvail(UART0_BASE)){
			str[i] = UARTCharGet(UART0_BASE);
			i++;
			SysCtlDelay(900000);
			GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_1, 2);
			SysCtlDelay(900000);
			GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_1, 0);
			}
		if((str[0] == 'G')){
			for(k=2;k<i;++k){			//retrieve values from the string
				if(str[k]=='X'){
					x = atof(&str[k+1]);
				}
				else if(str[k]=='Y'){
					y = atof(&str[k+1]);
				}
				else if(str[k]=='Z'){
					z = atof(&str[k+1]);
				}
				else if(str[k]=='F'){
					f = atof(&str[k+1]);
				}
				else if(str[k]=='S'){
					s = atof(&str[k+1]);
				}
				// execute moviment functions
			}
			else if(str[0] == 'P'){
				xrml = atoi(&str[2]);
				irml = 0;
				while(str[irml] != ','){
					++irml;
				}
				yrml = atoi(&str[irml+1]);
				if(str[1] == 'U'){
					// execute moviment functions					
				}
				else if(str[1] == 'D'){
					// execute moviment functions
				}

			}
		i = 0;
	}

Regards 
Adriano

Forum should "well" note the "above/beyond" skills & effort of vendor's Amit.     Bravo!

Not too many would, "dig so deep as to detect - then "fix" - an issue, "not yet recognized nor reported" by poster!     Outstanding!

Hello Amit, 

Thank you very much for your reply.

I took in consideration what you said, and performed the changes needed. But i´m still not being able to get more than 16 characters in the string. 

I´ll describe briefly what i´m doing: 

I´m connecting to the device using Putty. When I type a letter and press enter, one at a time, the string is successfully completed. But when i type, let´s say, 20 characters and press enter afterwards, only 16 of the 20 are stored.

Best regards

Adriano

Hi Amit,

Do you mean if the input stream is longer than the loop ? I see that if it is faster, the code still can catch the data even if the while loop is slow.

Regards,

Ahmed

Hello Amit,

I think in all cases if the stream is longer than 32 the loop will continue ! There is nothing to stop the loop as long as data is coming in UART.

Regards,

Ahmed