hello,I am trying to write my own ISR,but MPC555's Interrupt is somewhat different .
1. Its external interrupt sources share one Interrupt vector address--0x00000500 or 0xFFF00500, so i get confused.I wonder if there are two or more interrupt sources share 0x00000500, how does PowerPC choose the right ISR from many ISRs?
2. I write a PIT code here.It's not completed. Could someone tell me how to write the PIT's ISR?
UINT32 pitctr = 0; // Counter of PIT interrupts
void init555(int freq)
{
USIU.SYPCR.R = 0xffffff03; // Disable watchdog timer.
USIU.PLPRCRK.R = 0x55ccaa33; //Unlock PLPRC with special key
if (freq == 56)
{
USIU.PLPRCR.R = 0x00d3d000; // 14x PLL operation on normal power mode
}
else
{
USIU.PLPRCR.R = 0x0093d000; // 10x PLL operation on normal power mode
}
UIMB.UMCR.B.HSPEED = 0; // Make IMB clock = System Clock
}
void initPIT()
{ // SPECIFIC INITIALIZATIONS FOR PIT:
USIU.PITC.B.PITC = 1000; //Load desired count value
USIU.PISCR.B.PITF = 1; // Freeze enabled to stop PIT during debug mode
USIU.PISCR.B.PTE = 1; // Enable PIT to start counting
// LEVEL ASSIGNMENT:
USIU.PISCR.B.PIRQ = 0x80; // Assign PIT interrupt to Level 0
// ENABLE INTERRUPT
USIU.PISCR.B.PIE = 1; // Enable PIT interrupt
// SET APPROPRIATE MASK
USIU.SIMASK.R = 0x40000000; // Enable level 0 interrupt; others disabled
}
void main()
{
int i=0;
init555(40); // Perform minimal chip initialization
initPIT(); // Initialize PIT
asm(" mtspr EIE, r0"); // Enable interrupts
while (1) { i++; } // loop forever
}
/****************************ISR*********************************************/
void pitISR() // PIT interrupt service routine
{
USIU.PISCR.B.PS = 1; // Negate interrupt request
pitctr++; // Increment PIT interrupt counter
}
