read_me_first.txt

来自「最新版IAR FOR ARM（EWARM）5.11中的代码例子」· 文本 代码 · 共 71 行

This folder contains a set of example projects for the NXP LPC2103
evaluation board produced by IAR Systems Software.

As of 14 Jan 06 the examples consist of:

2103_FIQIntIRQ - Fast Interrupt Request interrupting an Interrupt Request
isr while it is executing.

2103_MultiBlink - Interrupts on MR0 for Timer0-3

2103_RTC_Ex - Create a 1Hz interrupt using RTC and put 350Hz 30% duty cycle
square wave out on Pin P0.5

2103_TMR0Int_Ex - Interrupt on MR0 of timer0 and set up interrupts for EXTINT1
and EXTINT2, which have buttons connected to those pins.

These examples use the iolpc2103.ddf file provided in the distribution. It is
HIGHLY recommended that if is desired to see the VIC register group, the user
take the following steps:
1. Make a local copy of the iolpc2103.ddf file
2. In the local copy, comment out the line

sfr = "VICVectAddr"           , "Memory", 0xFFFFF030,        4, base=16

3. In the line

group = "VIC","VICIRQStatus","VICFIQStatus","VICRawIntr","VICIntSelect","VICIntEnable","VICIntEnClear","VICSoftInt","VICSoftIntClear","VICProtection","VICVectAddr","VICDefVectAddr"...

Delet the reference to the register "VICVectAddr"

The reason for doing this is as follows: The original configuration of iolpc2103.ddf
enables C-SPY debugger to read and display the content of VICVectAddr. However, reading
this register affects the state machine of the vector interrupt controller state
machine. It has the effect of disabling further interrupts. This is an example of
the intrusiveness of the debugger. If it is desired to see the VICVectAddr during the
course of application exectuion, th work around is suggested.

Implement a single entry point interrupt handler for IRQ and inspect the temporary value
vector.

in startup code, put:
EXTERN irq_handler
org 0x18
ldr pc,=irq_handler

and in C module:

__irq __arm void irq_andler (void)        // IRQ_ISR_Handler() at 0x18
{
  void (*interrupt_function)(void);
  unsigned int vector;
  vector = VICVectAddr;                        // Get address of isr for this interrupt
  interrupt_function = (void(*)())vector;      // Call Tmr0IntOnMR0_isr thru pointer
  (*interrupt_function)();                     // Call vectored interrupt function
  VICVectAddr = 0;                             // Clear interrupt in VIC, complete interrupt cycle
}

void Tmr0IntOnMR0_isr(void)
{
  static unsigned int us_Ticks =0;
  unsigned int intrptID;
  us_Ticks++;
  if(us_Ticks == TICKS_PER_FIVEHUNDRED_MSEC)
  {
    bl_TimerFlag ^= 1;                         // The background "task"
    us_Ticks = 0;
  }
  intrptID = T0IR & 0xFF;                      // determine which channel
  T0IR = intrptID;
}