Specifications

Embedded System Tools Guide (EDK 6.2i) www.xilinx.com 339
UG111 (v1.4) January 30, 2004 1-800-255-7778
Example Systems for PowerPC
R
Example C Program
#include <xtmrctr_l.h>
#include <xgpio_l.h>
#include <xparameters.h>
/* Global variables: count is the count displayed using the
* LEDs, and timer_count is the interrupt frequency.
*/
unsigned int count = 1; /* default count */
unsigned int timer_count = 1; /* default timer_count */
/* timer interrupt service routine */
void timer_int_handler(void * baseaddr_p) {
unsigned int csr;
unsigned int gpio_data;
/* Read timer 0 CSR to see if it raised the interrupt */
csr = XTmrCtr_mGetControlStatusReg(XPAR_MYTIMER_BASEADDR, 0);
if (csr & XTC_CSR_INT_OCCURED_MASK) {
/* Increment the count */
if ((count <<= 1) > 8) {
count = 1;
}
/* Write value to gpio. 0 means light up, hence count is negated */
gpio_data = ~count;
XGpio_mSetDataReg(XPAR_MYGPIO_BASEADDR, gpio_data);
/* Clear the timer interrupt */
XTmrCtr_mSetControlStatusReg(XPAR_MYTIMER_BASEADDR, 0, csr);
}
}
void
main() {
unsigned int gpio_data;
/* Initialize exception handling */
XExc_Init();
/* Register external interrupt handler */
XExc_RegisterHandler(XEXC_ID_NON_CRITICAL_INT,
(XExceptionHandler)timer_int_handler, (void *)XPAR_MYTIMER_BASEADDR
);
/* Set the gpio as output on high 3 bits (LEDs)*/
XGpio_mSetDataDirection(XPAR_MYGPIO_BASEADDR, 0x00);
/* set the number of cycles the timer counts before interrupting */
XTmrCtr_mSetLoadReg(XPAR_MYTIMER_BASEADDR, 0,
(timer_count*timer_count+1) * 1000000);