User guide

ManualsBrandsARM ManualsComputer HardwareVERSION 1.2

100

return (oldvec);

}

#endif

/* Enabling and disabling interrupts

Interrupts are enabled or disabled by reading the cpsr flags

and updating bit 7.

These functions work only in a privileged mode, because the

control bits of the cpsr and spsr cannot be changed while in

User mode.

__inline void enable_IRQ(void)

{

int tmp;

__asm

{

MRS tmp, CPSR

BIC tmp, tmp, #0x80

MSR CPSR_c, tmp

}

__inline void disable_IRQ(void)

{

int tmp;

__asm

{

MRS tmp, CPSR

ORR tmp, tmp, #0x80

MSR CPSR_c, tmp

}

#ifdef EMBEDDED

extern void init_serial_A(void);

#endif

int main(void)

{

#ifdef EMBEDDED

#pragma import(__use_no_semihosting_swi) // ensure no functions that use

// semihosting SWIs are linked in

// from the C library

#ifdef USE_SERIAL_PORT

init_serial_A(); // Initialize serial port A

#endif

printf("RPS Timer Interrupt Example\n");

#ifdef EMBEDDED

#ifdef ROM_RAM_REMAP

printf("Embedded (ROM/RAM remap, no SWIs) version\n");

#else

printf("Embedded (ROM at 0x0, no SWIs) version\n");

#endif

#else

Install_Handler ((unsigned)IRQ_Handler, irqvec);

printf("Normal (RAM at 0x8000, semihosting) version\n\n");

#endif

printf("Initializing...\n");

enable_IRQ();

*IRQEnableClear = ~0; // Clear/disable all interrupts

*Timer1Control = 0; // Disable counters by clearing the control bytes

*Timer2Control = 0;

*Timer1Clear = 0 ; // Clear counter/timer interrupts by writing to

*Timer2Clear = 0 ; // the clear register - any data will work

*Timer1Load = FAST_LOAD; // Load counter values

Writing Code for ROM