I need a high resolution timer. I know that this may be done with PIT
(Programmable Interrupt Timer). I looked and used some examples about
this but CPU(MCF5234) was halted all time. I need examples which may
be useful.
Best regards.
#include "predef.h"
#include <stdio.h>
#include <ctype.h>
#include <startnet.h>
#include <autoupdate.h>
#include <dhcpclient.h>
#include <smarttrap.h>
#include <taskmon.h>
#include <sim5234.h>
#include <cfinter.h>
#include <pins.h>
extern "C"
{
void UserMain( void * pd );
void SetIntc( long func, int vector, int level, int prio );
}
const char * AppName = "MOD5234 PIT Example"; // App name for IPSetup
volatile DWORD pitr_count; // Global count variable
///////////////////////////////////////////////////////////////////////
// INTERRUPT - PIT interrupt service routine
INTERRUPT( my_pitr_func, 0x2600 )
{
WORD tmp = sim.pit[ 1 ].pcsr; // Get PIT1 Control & Status Register
// data
//
// Clear PIT1 - Refer to table 21-3 for more information on what
// bits are begin cleared and set
//
tmp &= 0xFF0F; // Bits 4-7 cleared
tmp |= 0x0F; // Bits 0-3 set
sim.pit[ 1 ].pcsr = tmp,
pitr_count++; // Increment when an interrupt occurs;
}
void SetUpPITR( int pitr_ch, WORD clock_interval, BYTE pcsr_pre /* See
table 21-3 in the reference manual for bits 8-11 */ )
{
WORD tmp;
if ((pitr_ch < 1) || (pitr_ch > 3))
{
iprintf( "*** ERROR - PIT channel out of range ***\r\n" );
return;
}
SetIntc( (long)&my_pitr_func, 36 + pitr_ch, 2 /* IRQ2 */, 3 );
//
// Configure the PIT for the specified time values
//
sim.pit[ pitr_ch ].pmr = clock_interval; // Set PIT modulus value
tmp = pcsr_pre;
tmp = (tmp << 8) | 0x0F;
sim.pit[ pitr_ch ].pcsr = tmp; // Set system clock divisor to 16 and
// set bits [3:0] in PCSR
}
/////////////////////////////////////////////////////////////////////////
// UserMain
//
void UserMain( void * pd )
{
InitializeStack();
if (EthernetIP == 0) GetDHCPAddress();
OSChangePrio( MAIN_PRIO );
EnableAutoUpdate();
EnableSmartTraps();
EnableTaskMonitor();
//
// Let us make bit happen at 1000 Hz. The base clock is
// 147,456,000 Hz, so the equation is:
//
// System_Clock_Frequency / 2
// PMR Value = ------------------------------- - 1
// Prescalar * Desired_Frequency
//
// 147456000 / 2
// PMR Value = --------------- - 1
// 16 * 1000
//
// PMR Value = 4607
//
// Not that the PIT Count Register is a 16-bit counter, so the
// clock count maximum is 65,535
//
SetUpPITR( 1 /* Use PIT1 */, 4607 /* Wait 4607 clocks */, 4 /*
Divide by 16 from table 21-3 (2^4) */ );
iprintf( "Application started\r\n" );
pitr_count = 0;
while (1)
{
OSTimeDly( TICKS_PER_SECOND );
iprintf( "PITR Count = %ld\r\n", pitr_count );
}
}
