以下是网上看到的例程：
没能理解，求解。
int
main(void)
{
volatile unsigned long ulLoop;
//
// Enable the GPIO port that is used for the on-board LED.
//
SYSCTL_RCGC2_R = SYSCTL_RCGC2_GPIOG;
//
// Do a dummy read to insert a few cycles after enabling the peripheral.
//
ulLoop = SYSCTL_RCGC2_R;
//
// Enable the GPIO pin for the LED (PG2). Set the direction as output, and
// enable the GPIO pin for digital function.
//
GPIO_PORTG_DIR_R = 0x04;
GPIO_PORTG_DEN_R = 0x04;
//
// Loop forever.
//
while(1)
{
//
// Turn on the LED.
//
GPIO_PORTG_DATA_R |= 0x04;
//
// Delay for a bit.
//
for(ulLoop = 0; ulLoop < 20; ulLoop++)
{
}
//
// Turn off the LED.
//
GPIO_PORTG_DATA_R &= ~(0x04);
//
// Delay for a bit.
//
for(ulLoop = 0; ulLoop < 20; ulLoop++)
{
}
}
} |
|
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