Sub-Second interrupt от RTC Опции

[evgen2]

Вот в LPC2378 есть в RTC регистр:

CISS Counter Increment select mask for R/W * 0xE002 4040 Sub-Second interrupt


The CISS register provides a way to obtain millisecond-range periodic CPU interrupts
from the Real Time Clock. This can allow freeing up one of the general purpose timers, or
support power saving by putting the CPU into a reduced power mode between periodic
interrupts.
Carry out signals from different stages of the Clock Tick Counter are used to generate the
sub-second interrupts. The possibilities range from 16 counts of the CTC (about
488microseconds), up to 2,048 counts of the CTC (about 62.5milliseconds). The
available counts and corresponding times are given in

1.) Сдается мне, что в доке в два раза наврано - не от 16 до 2048, а от 32 до 4096
2) А почему нет аналогов CISS не только у более старших чипов, но и у более младших ?

Сообщение отредактировал evgen2 - Apr 6 2010, 17:53

[evgen2]

А вот и код целиком

Код

#include "LPC23xx.H"                        /* LPC23xx/24xx definitions */
#define ILR_RTCCIF    0x01
#define ILR_RTCALF    0x02
#define ILR_RTSSF    0x04
#define CCR_CLKEN    0x01
#define CCR_CTCRST    0x02
#define CCR_CLKSRC    0x10

int nclock = 0, nclocks = 0, t0=0, dt0=0;

volatile int alarm_on = 0;

__irq  void RTCHandler (void)
{  
//  RTC_ILR |= ILR_RTCCIF;        /* clear interrupt flag */
    RTC_ILR |= ILR_RTSSF;
    alarm_on = 1;
    VICVectAddr = 0;        /* Acknowledge Interrupt */
}

int stat[256];
/*****************************************************************************
**   Main Function  main()
******************************************************************************/
int main (void)
{    int i, dtmin, dtmax;
    for(i=0;i<256; i++) stat[i]=0;
    /*--- Initialize registers ---*/    
    RTC_AMR = 0;
    RTC_CIIR = 0;
    RTC_CCR = CCR_CTCRST; //Сброс
    RTC_CCR = CCR_CLKSRC; //

VICIntSelect   = 0x00000000;  
VICVectAddr13 = (unsigned) RTCHandler;
VICVectCntl13 = 0x00000013;            /* Set channel =RTC */
VICIntEnable = (1<<13);                /* Enable the interrupt */

    /*--- Start RTC counters ---*/
    RTC_CCR |= CCR_CLKEN;
    RTC_ILR = ILR_RTCCIF;
    RTC_CISS = 0x81; //subsecondes interrupt enable 0x80 = 488 мкс; 0x87 = 62.5 мс;

    t0 = RTC_CTC;
    dtmax = 0;
    dtmin = 1000000;
    while (1)
    {    /* Loop forever */
        nclocks++;
        if ( alarm_on != 0 )
        {    dt0 = RTC_CTC - t0;
            t0 = RTC_CTC;

// RTC_CISS = 0x80;
//Simulator:  dtmin = 0x20 dtmax = 0x20 RTC_CISS = 0x80;  stat[]= 0,0,0,0.....     stat[16] = много
//JTAG debug: dtmin = 0x0  dtmax = 0x20 RTC_CISS = 0x80;  stat[]= 1,0,1,0.....     stat[32] = много
// RTC_CISS = 0x81;
//Simulator: dtmin = 0x40 dtmax = 0x40 RTC_CISS = 0x80;  stat[]= 0,0,0,0.....     stat[32] = много
//JTAG debug:dtmin = 0x0  dtmax = 0x40 RTC_CISS = 0x80;  stat[]= 1,0,1,0.....     stat[64] = много
            if(dt0 >= 0)
            {  if(dt0 > dtmax) dtmax = dt0;
               if(dt0 < dtmin) dtmin = dt0;
               if(dt0<256)
                 stat[dt0]++;
            }
            alarm_on = 0;
            nclock++;
        }
    }
    return 0;
}