home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Technotools
/
Technotools (Chestnut CD-ROM)(1993).ISO
/
lang_c
/
cuj9205
/
1005066a
< prev
next >
Wrap
Text File
|
1992-06-02
|
3KB
|
121 lines
/* Listing 6 */
/*****************************************************
TIMER.C
Basic Routines for programming the 9513 timer
counter on the Lab Master AD.
Copyright Don Bradley, 1991.
Permission is granted for used of these routines
in any manner as long as this copyright notice is
included.
Tested using Quick C 2.5 and MSC 6.0 on a
Toshiba T5200.
*****************************************************/
#include <math.h>
#include <conio.h>
#include "labmastr.h"
void timer_reset()
{
/* reset 9513 timer\counter */
outp(TIMER_CONTROL, 0xFF);
/* Enable 16-bit Data Access */
outp(TIMER_CONTROL, 0xEF);
/* initalize master mode reg */
outp(TIMER_CONTROL, 0x17);
/* BCD Division, 16 Bit Data */
outpw(TIMER_DATA, 0xA000);
}
void timer5_on()
/*& Turns timer 5 on. Used to start ADC output from the
fifo thru manual or DMA control. */
{
/* turn timer 5 on */
outp(TIMER_CONTROL, 0x30);
}
void timer5_off()
/*& Turns timer 5 off. Used to stop or disable ADC
output from the fifo thru manual or DMA control. */
{
/* turn timer 5 off */
outp(TIMER_CONTROL, 0xD0);
}
#define COUNTSTART 0xb
#define COUNTHIGH 0xf
double timerad(double freq)
/*& Sets timer 5 of the labmaster board to the desired
frequency for data collection. */
{
double time;
unsigned count = COUNTSTART;
time = TIMER_F1 / freq;
while (1) {
if (time < 65536.0)
break;
time /= TIMER_DIVISOR;
++count;
}
if (count <= COUNTHIGH) {
timer5_off();
freq = TIMER_F1 / ((unsigned) (time) *
pow(10.0, (double) (count - COUNTSTART)));
// initalize master mode register
outp(TIMER_CONTROL, 0x17);
// BCD Division, 16 Bit Data Bus counter 5 setup
outpw(TIMER_DATA, 0xA000);
outp(TIMER_CONTROL, 0x5);
// No Gating, Count on Rising Edge,
// F(count-COUNTSTART), Count Repetitively,
// Count Down, Active High Terminal Count Pulse
// frequency range 400Hz to 4MHz
outpw(TIMER_DATA, (count << 8) | 0x21);
outpw(TIMER_DATA, (int) time);
timer5_on();
}
else
freq = 0.0;
return (freq);
}
void step_timerad()
{
timer5_off();
// Point to Counter 5
outp(TIMER_CONTROL, 0x5);
// Active High output, Count Down, Binary Counting,
// Count Repeatedly, Reload from Load Register
// only, No Gateing, No Special Gate, Count Falling
// Edges and Use Source 5.
outpw(TIMER_DATA, 0x1521);
outpw(TIMER_DATA, 2);
// Load Counter 5
outp(TIMER_CONTROL, 0x50);
timer5_on()
// Step Counter 5
outp(TIMER_CONTROL, 0xF5);
}