Using multiple UARTs simultaneously on EK TM4C123GXL board

Hi Rituraj,

Did you setup the interrupt handler for UART 1 at startup file?

- kel

Hey kel,
Yes, I did set the UART Handler for both UART0 and UART1 in the startup.ccs file. I replaced IntDefaultHandler with UARTIntHandler for both UART0 and UART1. But it gets stuck at the place where I enable both interrupts. Not if I enable either one.

Another thing I wanted to ask: One of my friends said that I need to set the priorities for the interrupts if I need to use more than 1 UART. Is this true? Shouldn't declaring the interrupts take care of the whole situation? Thanks!

Hi,

Post your startup.ccs interrupt vector table here for review. Also post your modified uart_echo code here for review.

If you use UARTIntHandler for both UART0 and UART1, there seem to be a problem there. I have not done the same so I do not know what would be the effect of that.

The usual practice to have a specific Interrupt Handler for that peripheral. Example UART0IntHandler for UART0 and UART1IntHandler for UART1.

- kel

Hi kel,
follwing is the code in uart_echo.c

//*****************************************************************************
//
// uart_echo.c - Example for reading data from and writing data to the UART in
// an interrupt driven fashion.
//
// Copyright (c) 2012-2014 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 2.1.0.12573 of the EK-TM4C123GXL Firmware Package.
//
//*****************************************************************************
#include <stdint.h>
#include <stdbool.h>
#include "hw_ints.h"
#include "hw_memmap.h"
#include "debug.h"
#include "fpu.h"
#include "gpio.h"
#include "interrupt.h"
#include "pin_map.h"
#include "rom.h"
#include "sysctl.h"
#include "uart.h"
//*****************************************************************************
//
//! \addtogroup example_list
//! <h1>UART Echo (uart_echo)</h1>
//!
//! This example application utilizes the UART to echo text. The first UART
//! (connected to the USB debug virtual serial port on the evaluation board)
//! will be configured in 115,200 baud, 8-n-1 mode. All characters received on
//! the UART are transmitted back to the UART.
//
//*****************************************************************************
//*****************************************************************************
//
// The error routine that is called if the driver library encounters an error.
//
//*****************************************************************************
#ifdef DEBUG
void
__error__(char *pcFilename, uint32_t ui32Line)
{
}
#endif
//*****************************************************************************
//
// The UART interrupt handler.
//
//*****************************************************************************
void
UARTIntHandler(void)
{
uint32_t ui32Status;
//
// Get the interrrupt status.
//
ui32Status = ROM_UARTIntStatus(UART0_BASE, true);
//
// Clear the asserted interrupts.
//
ROM_UARTIntClear(UART0_BASE, ui32Status);
//
// Loop while there are characters in the receive FIFO.
//
while(ROM_UARTCharsAvail(UART0_BASE))
{
//
// Read the next character from the UART and write it back to the UART.
//
ROM_UARTCharPutNonBlocking(UART0_BASE,
ROM_UARTCharGetNonBlocking(UART0_BASE));
//
// Blink the LED to show a character transfer is occuring.
//
GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_2, GPIO_PIN_2);
//
// Delay for 1 millisecond. Each SysCtlDelay is about 3 clocks.
//
SysCtlDelay(SysCtlClockGet() / (1000 * 3));
//
// Turn off the LED
//
GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_2, 0);
}
}

void
UART1IntHandler(void)
{
uint32_t ui32Status;
//
// Get the interrrupt status.
//
ui32Status = ROM_UARTIntStatus(UART1_BASE, true);
//
// Clear the asserted interrupts.
//
ROM_UARTIntClear(UART1_BASE, ui32Status);
//
// Loop while there are characters in the receive FIFO.
//
while(ROM_UARTCharsAvail(UART1_BASE))
{
//
// Read the next character from the UART and write it back to the UART.
//
ROM_UARTCharPutNonBlocking(UART1_BASE,
ROM_UARTCharGetNonBlocking(UART1_BASE));
//
// Blink the LED to show a character transfer is occuring.
//
GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_2, GPIO_PIN_2);
//
// Delay for 1 millisecond. Each SysCtlDelay is about 3 clocks.
//
SysCtlDelay(SysCtlClockGet() / (1000 * 3));
//
// Turn off the LED
//
GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_2, 0);
}
}
//*****************************************************************************
//
// Send a string to the UART.
//
//*****************************************************************************
void
UARTSend(const uint8_t *pui8Buffer, uint32_t ui32Count)
{
//
// Loop while there are more characters to send.
//
while(ui32Count--)
{
//
// Write the next character to the UART.
//
ROM_UARTCharPutNonBlocking(UART0_BASE, *pui8Buffer++);
}
}


void
UART1Send(const uint8_t *pui8Buffer, uint32_t ui32Count)
{
//
// Loop while there are more characters to send.
//
while(ui32Count--)
{
//
// Write the next character to the UART.
//
ROM_UARTCharPutNonBlocking(UART1_BASE, *pui8Buffer++);
}
}
//*****************************************************************************
//
// This example demonstrates how to send a string of data to the UART.
//
//*****************************************************************************
int
main(void)
{
//
// Enable lazy stacking for interrupt handlers. This allows floating-point
// instructions to be used within interrupt handlers, but at the expense of
// extra stack usage.
//
ROM_FPUEnable();
ROM_FPULazyStackingEnable();
//
// Set the clocking to run directly from the crystal.
//
ROM_SysCtlClockSet(SYSCTL_SYSDIV_1 | SYSCTL_USE_OSC | SYSCTL_OSC_MAIN |
SYSCTL_XTAL_16MHZ);
//
// Enable the GPIO port that is used for the on-board LED.
//
ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOF);
//
// Enable the GPIO pins for the LED (PF2).
//
ROM_GPIOPinTypeGPIOOutput(GPIO_PORTF_BASE, GPIO_PIN_2);
//
// Enable the peripherals used by this example.
//
ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_UART0);
ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOA);

ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_UART1);
ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOB);
//
// Enable processor interrupts.
//
ROM_IntMasterEnable();
//
// Set GPIO A0 and A1 as UART pins.
//
GPIOPinConfigure(GPIO_PA0_U0RX);
GPIOPinConfigure(GPIO_PA1_U0TX);
ROM_GPIOPinTypeUART(GPIO_PORTA_BASE, GPIO_PIN_0 | GPIO_PIN_1);

GPIOPinConfigure(GPIO_PB0_U1RX);
GPIOPinConfigure(GPIO_PB1_U1TX);
ROM_GPIOPinTypeUART(GPIO_PORTB_BASE, GPIO_PIN_0 | GPIO_PIN_1);
//
// Configure the UART for 115,200, 8-N-1 operation.
//
ROM_UARTConfigSetExpClk(UART0_BASE, ROM_SysCtlClockGet(), 115200,
(UART_CONFIG_WLEN_8 | UART_CONFIG_STOP_ONE |
UART_CONFIG_PAR_NONE));

ROM_UARTConfigSetExpClk(UART1_BASE, ROM_SysCtlClockGet(), 115200,
(UART_CONFIG_WLEN_8 | UART_CONFIG_STOP_ONE |
UART_CONFIG_PAR_NONE));
//
// Enable the UART interrupt.
//
ROM_IntEnable(INT_UART0);
ROM_UARTIntEnable(UART0_BASE, UART_INT_RX | UART_INT_RT);

ROM_IntEnable(INT_UART1);
ROM_UARTIntEnable(UART1_BASE, UART_INT_RX | UART_INT_RT);
//
// Prompt for text to be entered.
//
UARTSend((uint8_t *)"\033[2JEnter text: ", 16);
UART1Send((uint8_t *)"\033[2JEnter text: ", 16);
//
// Loop forever echoing data through the UART.
//
while(1)
{
}
}




and my startup.ccs file:


//*****************************************************************************
// Forward declaration of the default fault handlers.
//*****************************************************************************
void ResetISR(void);
static void NmiSR(void);
static void FaultISR(void);
static void IntDefaultHandler(void);

//*****************************************************************************
// External declaration for the reset handler that is to be called when the
// processor is started
//*****************************************************************************
extern void _c_int00(void);

//*****************************************************************************
// Linker variable that marks the top of the stack.
//*****************************************************************************
extern unsigned long __STACK_TOP;

//*****************************************************************************
// External declaration for the interrupt handler used by the application.
//*****************************************************************************
extern void UARTIntHandler(void);
extern void UART1IntHandler(void);

//*****************************************************************************
// The vector table. Note that the proper constructs must be placed on this to
// ensure that it ends up at physical address 0x0000.0000 or at the start of
// the program if located at a start address other than 0.
//*****************************************************************************
#pragma DATA_SECTION(g_pfnVectors, ".intvecs")
void (* const g_pfnVectors[])(void) =
{
(void (*)(void))((unsigned long)&__STACK_TOP),
// The initial stack pointer
ResetISR,// The reset handler
NmiSR,// The NMI handler
FaultISR,// The hard fault handler
IntDefaultHandler,// The MPU fault handler
IntDefaultHandler,// The bus fault handler
IntDefaultHandler,// The usage fault handler
0,// Reserved
0,// Reserved
0,// Reserved
0,// Reserved
IntDefaultHandler,// SVCall handler
IntDefaultHandler,// Debug monitor handler
0,// Reserved
IntDefaultHandler,// The PendSV handler
IntDefaultHandler,// The SysTick handler
IntDefaultHandler,// GPIO Port A
IntDefaultHandler,// GPIO Port B
IntDefaultHandler,// GPIO Port C
IntDefaultHandler,// GPIO Port D
IntDefaultHandler,// GPIO Port E
UARTIntHandler,// UART0 Rx and Tx
UART1IntHandler,// UART1 Rx and Tx
IntDefaultHandler,// SSI0 Rx and Tx
IntDefaultHandler,// I2C0 Master and Slave
IntDefaultHandler,// PWM Fault
IntDefaultHandler,// PWM Generator 0
IntDefaultHandler,// PWM Generator 1
IntDefaultHandler,// PWM Generator 2
IntDefaultHandler,// Quadrature Encoder 0
IntDefaultHandler,// ADC Sequence 0
IntDefaultHandler,// ADC Sequence 1
IntDefaultHandler,// ADC Sequence 2
IntDefaultHandler,// ADC Sequence 3
IntDefaultHandler,// Watchdog timer
IntDefaultHandler,// Timer 0 subtimer A
IntDefaultHandler,// Timer 0 subtimer B
IntDefaultHandler,// Timer 1 subtimer A
IntDefaultHandler,// Timer 1 subtimer B
IntDefaultHandler,// Timer 2 subtimer A
IntDefaultHandler,// Timer 2 subtimer B
IntDefaultHandler,// Analog Comparator 0
IntDefaultHandler,// Analog Comparator 1
IntDefaultHandler,// Analog Comparator 2
IntDefaultHandler,// System Control (PLL, OSC, BO)
IntDefaultHandler,// FLASH Control
IntDefaultHandler,// GPIO Port F
IntDefaultHandler,// GPIO Port G
IntDefaultHandler,// GPIO Port H
IntDefaultHandler,// UART2 Rx and Tx
IntDefaultHandler,// SSI1 Rx and Tx
IntDefaultHandler,// Timer 3 subtimer A
IntDefaultHandler,// Timer 3 subtimer B
IntDefaultHandler,// I2C1 Master and Slave
IntDefaultHandler,// Quadrature Encoder 1
IntDefaultHandler,// CAN0
IntDefaultHandler,// CAN1
IntDefaultHandler,// CAN2
IntDefaultHandler,// Ethernet
IntDefaultHandler,// Hibernate
IntDefaultHandler,// USB0
IntDefaultHandler,// PWM Generator 3
IntDefaultHandler,// uDMA Software Transfer
IntDefaultHandler,// uDMA Error
IntDefaultHandler,// ADC1 Sequence 0
IntDefaultHandler,// ADC1 Sequence 1
IntDefaultHandler,// ADC1 Sequence 2
IntDefaultHandler,// ADC1 Sequence 3
IntDefaultHandler,// I2S0
IntDefaultHandler,// External Bus Interface 0
IntDefaultHandler,// GPIO Port J
IntDefaultHandler,// GPIO Port K
IntDefaultHandler,// GPIO Port L
IntDefaultHandler,// SSI2 Rx and Tx
IntDefaultHandler,// SSI3 Rx and Tx
IntDefaultHandler,// UART3 Rx and Tx
IntDefaultHandler,// UART4 Rx and Tx
IntDefaultHandler,// UART5 Rx and Tx
IntDefaultHandler,// UART6 Rx and Tx
IntDefaultHandler,// UART7 Rx and Tx
0,// Reserved
0,// Reserved
0,// Reserved
0,// Reserved
IntDefaultHandler,// I2C2 Master and Slave
IntDefaultHandler,// I2C3 Master and Slave
IntDefaultHandler,// Timer 4 subtimer A
IntDefaultHandler,// Timer 4 subtimer B
0,// Reserved
0,// Reserved
0,// Reserved
0,// Reserved
0,// Reserved
0,// Reserved
0,// Reserved
0,// Reserved
0,// Reserved
0,// Reserved
0,// Reserved
0,// Reserved
0,// Reserved
0,// Reserved
0,// Reserved
0,// Reserved
0,// Reserved
0,// Reserved
0,// Reserved
0,// Reserved
IntDefaultHandler,// Timer 5 subtimer A
IntDefaultHandler,// Timer 5 subtimer B
IntDefaultHandler,// Wide Timer 0 subtimer A
IntDefaultHandler,// Wide Timer 0 subtimer B
IntDefaultHandler,// Wide Timer 1 subtimer A
IntDefaultHandler,// Wide Timer 1 subtimer B
IntDefaultHandler,// Wide Timer 2 subtimer A
IntDefaultHandler,// Wide Timer 2 subtimer B
IntDefaultHandler,// Wide Timer 3 subtimer A
IntDefaultHandler,// Wide Timer 3 subtimer B
IntDefaultHandler,// Wide Timer 4 subtimer A
IntDefaultHandler,// Wide Timer 4 subtimer B
IntDefaultHandler,// Wide Timer 5 subtimer A
IntDefaultHandler,// Wide Timer 5 subtimer B
IntDefaultHandler,// FPU
IntDefaultHandler,// PECI 0
IntDefaultHandler,// LPC 0
IntDefaultHandler,// I2C4 Master and Slave
IntDefaultHandler,// I2C5 Master and Slave
IntDefaultHandler,// GPIO Port M
IntDefaultHandler,// GPIO Port N
IntDefaultHandler,// Quadrature Encoder 2
IntDefaultHandler,// Fan 0
0,// Reserved
IntDefaultHandler,// GPIO Port P (Summary or P0)
IntDefaultHandler,// GPIO Port P1
IntDefaultHandler,// GPIO Port P2
IntDefaultHandler,// GPIO Port P3
IntDefaultHandler,// GPIO Port P4
IntDefaultHandler,// GPIO Port P5
IntDefaultHandler,// GPIO Port P6
IntDefaultHandler,// GPIO Port P7
IntDefaultHandler,// GPIO Port Q (Summary or Q0)
IntDefaultHandler,// GPIO Port Q1
IntDefaultHandler,// GPIO Port Q2
IntDefaultHandler,// GPIO Port Q3
IntDefaultHandler,// GPIO Port Q4
IntDefaultHandler,// GPIO Port Q5
IntDefaultHandler,// GPIO Port Q6
IntDefaultHandler,// GPIO Port Q7
IntDefaultHandler,// GPIO Port R
IntDefaultHandler,// GPIO Port S
IntDefaultHandler,// PWM 1 Generator 0
IntDefaultHandler,// PWM 1 Generator 1
IntDefaultHandler,// PWM 1 Generator 2
IntDefaultHandler,// PWM 1 Generator 3
IntDefaultHandler// PWM 1 Fault
};

//*****************************************************************************
//
// This is the code that gets called when the processor first starts execution
// following a reset event. Only the absolutely necessary set is performed,
// after which the application supplied entry() routine is called. Any fancy
// actions (such as making decisions based on the reset cause register, and
// resetting the bits in that register) are left solely in the hands of the
// application.
//
//*****************************************************************************
void ResetISR(void) {
// Jump to the CCS C initialization routine. This will enable the
// floating-point unit as well, so that does not need to be done here.
__asm(" .global _c_int00\n"
" b.w _c_int00");
}

//*****************************************************************************
//
// This is the code that gets called when the processor receives a NMI. This
// simply enters an infinite loop, preserving the system state for examination
// by a debugger.
//
//*****************************************************************************
static void NmiSR(void) {
// Enter an infinite loop.
while (1) {
}
}

//*****************************************************************************
//
// This is the code that gets called when the processor receives a fault
// interrupt. This simply enters an infinite loop, preserving the system state
// for examination by a debugger.
//
//*****************************************************************************
static void FaultISR(void) {
// Enter an infinite loop.
while (1) {
}
}

//*****************************************************************************
//
// This is the code that gets called when the processor receives an unexpected
// interrupt. This simply enters an infinite loop, preserving the system state
// for examination by a debugger.
//
//*****************************************************************************
static void IntDefaultHandler(void) {
// Go into an infinite loop.
while (1) {
}
}



In a nutshell,
1. I Replaced IntDefaultHandler with UARTIntHandler for UART0 and UART1IntHandler for UART1, and
2. defined the UART1IntHandler in uart_echo.c.

3. defined UART1Send