Posted on May 17, 2011 at 12:29Thank you for the response.
This problem is a little difficult to identify because it has happened on a simple LED blink program that doesn't have any relation to the JTAG pins. It does the following:
1. Set up a simple vector table
2. Enable an I/O
3. Toggle the I/O with a delay
The code downloaded and runs because I can see the LED blink, but the JTAG doesn't respond any more. I took this identical program and ran it on the Sandstorm version and it had the same problem with the JTAG port, but the recovery process allowed me to regain control of the JTAG port.
I was just reading about the boot option and this may prevent the problem I have seen in the Luminary parts.
Here is the code:
// basic.c for the LM3S317
//Declare functions
int main(void);
void nmi_handler(void);
void hardfault_handler(void);
//Define the vector table
__attribute__ ((section(''vectors'')))
int const VectorStackTop = 0x20000800;
__attribute__ ((section(''vectors'')))
int (* const VectorMain) (void) = main;
__attribute__ ((section(''vectors'')))
void (* const VectorNMI) (void) = nmi_handler;
__attribute__ ((section(''vectors'')))
void (* const VectorHardFault) (void) = hardfault_handler;
//Dummy Handlers
void nmi_handler(void)
{
return;
}
void hardfault_handler(void)
{
return;
}
//*****************************************************************************
// Declarations
//*****************************************************************************
#define RCGC2 0x400FE108
#define RCGC2_GPIOB 1<
#define GPIO_PORTB 0x40005000
#define GPIODATA 0x0000
#define GPIODIR 0x0400
#define GPIODEN 0x051C
#define PB3 1<
#define GPIO_MASK PB3<
#define SYSCTL_RCGC2_P (*((volatile unsigned long *)(RCGC2)))
#define PBDIR (*((volatile unsigned long *)(GPIO_PORTB+GPIODIR)))
#define PBDEN (*((volatile unsigned long *)(GPIO_PORTB+GPIODEN)))
#define PBDATA (*((volatile unsigned long *)(GPIO_PORTB+(GPIO_MASK))))
//*****************************************************************************
// Initialize LED
//*****************************************************************************
void initLED (void)
{
SYSCTL_RCGC2_P=RCGC2_GPIOB; //Enable Port B clocking
PBDIR=PB3; //Port B pin 3 output
PBDEN=PB3; //Port B pin 3 digital enable
}
//*****************************************************************************
// LED on
//*****************************************************************************
void LEDon (void)
{
PBDATA=PB3;
}
//*****************************************************************************
// LED off
//*****************************************************************************
void LEDoff (void)
{
PBDATA=0x00;
}
//*****************************************************************************
// Main
//*****************************************************************************
int main(void)
{
volatile unsigned long ulLoop;
initLED(); //Set up LED port
while(1)
{
for(ulLoop = 0; ulLoop < 0x10000; ulLoop++)
{
}
LEDon();
for(ulLoop = 0; ulLoop < 0x10000; ulLoop++)
{
}
LEDoff();
}
}
