Delay in Z8 encore

[bryanleo]

Hi

How do you incorporate delay?

And how is the delay_milliseconds() used? <-- will this be enough?

The reason, I'm asking this is that my MCU is polling a multiplexer. I wanted to incorporate a delay so that it would read data slower so that I can transmit data slower as well.

Thanks,
Bryan

[mArKhAo]

hehe. si sir.paranz ang makakasagot nyan.

[paranz]

you can use a software delay, which is not accurate.

Code:

void delay(void)
{
     int i;
     for(i=0;i<0xFFFF;i++)
            ;                                //do nothing
}

the problem above is that the exact amount delay is difficult to set (by trial and error?). Just try changing 0xFFFF to any value you deem acceptable

Or you can use the Timer module (hardware-based delay) in the mcu. The 40-pin Z8 encore have 3 Timers, you can use one of these initialized in ONE-SHOT MODE. In ONE-SHOT mode, the Timer will overflow only once. This is an accurate hardware-based delay.

[bryanleo]

Thanks a lot! 
I will try this out later.


By the way, what is the rough estimate in seconds of the delay of the 0xFFFF value?
Can the delay be extended by adding another loop inside the for loop like....

void delay(void)
{
   int i,j;
   for(i=0;i<=0xFFFF;i++)
      for(j=0;j<=0xFFFF;j++)
         ; //do nothing
}

[beginner wan]

pwede po yan.. pero mas maganda ata kung tatawagin mo nalang yung delay function na dalawang beses..

like..

{.....
  delay();
  delay();
  ...
}

at least, pwede ka magdelay ng mas mabilis..

[paranz]

yup tama po kayong dalawa 

[mochini77]

You can also try to use the sample code below to introduce a specific time delay in your application.
Take note that it uses timer interrupt which depends on your clock frequency.

You just need to call Delayms (x) where x is in milliseconds.
e.i.
     Delayms (100);

Code:

#include <ez8.h>

/* Function Prototypes and Definitions */
#define SET 1
#define RESET 0

void Init_Timer0(void );
void Delayms (unsigned int milliseconds);

unsigned char  Millisecond_50=RESET;
static unsigned int s_Ticks,s_Current_Milliseconds; /* Used by delayms() & isr_timer0() */

void Init_Timer0(void)
{
     T0H = 0x00; /* Start value = 0 */
     T0L = 0x00;
     T0RH = 0x4E; /* 1ms reload counter with 20MHz system clock */
     T0RL = 0x00;
     T0CTL = 0x01; /* Continuous mode; clock divide by 1 */
     IRQ0ENH |= 0x20; /* Timer 0 has normal priority */
     IRQ0ENL |= 0x20;
}

/*  Interrupt service routine for Timer0 */
#pragma interrupt
void isr_Timer0(void)
{
     SET_VECTOR(TIMER0,isr_Timer0);
     s_Ticks++; /* at every 1ms increment counter */
     if(s_Ticks==50)
     {
          Millisecond_50=SET; /* Set flag on 50ms timeout */
          s_Ticks=0; /* Reset counter */
     }
     s_Current_Milliseconds++ ; /* counter used for Delayms() funciton */
}

/* This function provides delay in milliseconds */
/* milliseconds Delay duration in milliseconds  */
void Delayms (unsigned int milliseconds)
{
     s_Current_Milliseconds = 0;
     T0CTL &= 0x7F; /* Disable Timer0 */
     T0H = 0x00 ; /* Restart from 0 */
     T0L = 0x00 ;
     T0CTL |= 0x80 ; /* Put On Timer0 */
     while (s_Current_Milliseconds < milliseconds); /* wait till specified timeout occurs */
}

[bryanleo]

Salamat sa inyong lahat! geleng

['yus]

meron bang timer calculator for zilog?

[paranz]

^ wala. Hand calculation lang ang gamit for using hardware timers

[SpongeBob]

kung ano value ng reload at prescaler yun ang delay

Time-Out Period = (Reload Value x Prescaler Value) / System Clock Frequency (Hz)

['yus]

galing sa "Z8 Encore XP F0823 Series Product Specification"

Table 101. Oscillator Configuration and Selection
Clock Source:
Internal Precision
RC Oscillator

Characteristics:
 • 32.8 kHz or 5.53 MHz
 • ± 4% accuracy when trimmed
 • No external components required
 • Unlock and write Oscillator Control

Required Setup:
Register (OSCCTL) to enable and
select oscillator at either 5.53 MHz or
32.8 kHz

kanina ko lang nabasa.. 4% accuracy pala..  


EDIT: magkaiba nga pala ang definition ng "Precision" saka ng "Accuracy" hehe

[piona]

yah tama ka Yus, +/-4% accurate siya sa designed freq, at stable naman ang freq niya......siguro sa range ng operating temp. niya