After decades of using the PIC, I have taken the leap of faith to the ARM..
I am using the IAR toolchain and all I want to do is flash an LED. I have 'borrowed' the following code that compiles OK, but when I single step through it, once the registers have been set the PDSR does not change. Stupid question, but how can I tell if my port pin is toggling...
I am also having nightmares with the SAM-ICE JTAG, but I will put that in another post.
#include <AT91SAM7S256.h>
#define LED (1<<0) // PA0
#define INPUT_PIN (1<<1) // PA1
#define INT_PIN (1<<2) // PA2
static void initialize( void);
void delay_us( int time);
void delay_ms( int time);
int main(void)
{
int delay = 100;
volatile long input;
initialize();
volatile AT91PS_PIO pPIOA = AT91C_BASE_PIOA;
while(1)
{
input = pPIOA->PIO_PDSR; //for debugging. Watch input variable to check if inputs working.
if(( pPIOA->PIO_PDSR & INPUT_PIN) == INPUT_PIN)
delay = 1000;
else
delay = 100;
pPIOA->PIO_CODR = LED;
delay_ms(delay);
pPIOA->PIO_SODR = LED;
delay_ms(delay);
}
}
static void initialize(void)
{
//Turn on the peripheral clock. Without this on, inputs do not actually register in the PDSR register
volatile AT91PS_PMC pPMC = AT91C_BASE_PMC; // pointer to PMC data structure
pPMC->PMC_PCER = (1<<AT91C_ID_PIOA); // enable Timer0 peripheral clock
volatile AT91PS_PIO pPIOA = AT91C_BASE_PIOA;
pPIOA->PIO_PER = (LED | INPUT_PIN); // Set PIO to control LED and button.
// Initialize Input
pPIOA->PIO_ODR = INPUT_PIN ; // Disable outputs for INPUT pins. (not needed as all pins default input on reset)
pPIOA->PIO_PPUER = INPUT_PIN; //Pullup Enable (not needed as all pullups are enabled on reset)
// Initialize Output
pPIOA->PIO_OER = LED; // Enable output for LED.
pPIOA->PIO_SODR = LED; // Turn LED off.
pPIOA->PIO_PPUDR = LED; //Pullup disable
}
void delay_us(int delay)
{
while(delay--)
{
__asm ("NOP");
__asm ("NOP");
__asm ("NOP");
__asm ("NOP");
__asm ("NOP");
__asm ("NOP");
__asm ("NOP");
__asm ("NOP");
__asm ("NOP");
__asm ("NOP");
__asm ("NOP");
__asm ("NOP");
__asm ("NOP");
}
}
void delay_ms(int delay)
{
char i;
while(delay--)
{
for(i=0; i<4; i++)
{
delay_us(250);
}
}
}
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