Discussion in "8051 Discussion Forum" started by    wounder    Jan 25, 2020.
Sat Jan 25 2020, 12:14 PM
#1
I have a 8051 micro controller ,it has timer0,1,2,3 with different modes.

in timer0,mode0, i got a sample code (as shown below).

from that code

TH0_INIT=0xFC //5.0ms@XTAL=12MHz, Period = (10.85/2) ms@XTAL=22.1184MHz TL0_INIT=0x0F

both TH0,TL0 load with hex values..but could not derive these values from equation below .. (https://exploreembedded.com/wiki/5.8051_Timer_programming) Could you please tell me ,how these hex values derive ??

tick = (1/(Fosc/12)

tick = 12/Fosc$$ For Fosc == 11.0592Mhz, the tick time will be

tick = 12/11.0592M = 1.085069444us = 1.085us

Now the Timer value for the required delay can be calculated as below.

Delay = TimerCount * tick

Count = (Delay/tick)

RegValue = TimerMax- Count RegValue = TimerMax-(Delay/tick) = TimerMax - (Delay/1.085us)

RegValue = TimerMax-((Delay/1.085) * 10^6)$$


#include "SFR_Macro.h"
#include "Function_define.h"

#define TH0_INIT 0xFC //5.0ms@XTAL=12MHz, Period = (10.85/2)
ms@XTAL=22.1184MHz
#define TL0_INIT 0x0F


void Timer0_ISR (void) interrupt 1 //interrupt address is 0x000B
{
TH0 = TH0_INIT;
TL0 = TL0_INIT;
P12 = ~P12; // GPIO
toggle when interrupt
}



void main (void)
{
TMOD = 0XFF;
Set_All_GPIO_Quasi_Mode;
TIMER0_MODE0_ENABLE;


clr_T0M;
clr_T1M;

TH0 = TH0_INIT;
TL0 = TL0_INIT;


// set_ET0; //enable Timer0 interrupt
//enable Timer1 interrupt
set_EA; //enable interrupts

set_TR0; //Timer0 run


while(1)
{
TH0 = TH0_INIT;
TL0 = TL0_INIT;
set_TR0;
while(!TF0);
clr_TR0;
P12 = ~P12;
TF0 = 0 ;
}
}
Sun Jan 26 2020, 04:05 AM
#2
For a 12MHz crystal using a normal divided by 12 clock.

For a 5mS delay I get
TH0_INIT=0xEC
TL0_INIT=0x78
What do you get ?

The program you posted uses polling and an interrupt to monitor the timer
and toggle P12, choose one, you can't (at least shouldn't) do both.

Get Social

Information

Powered by e107 Forum System

Conversation

Wed Oct 27 2021, 12:29 PM
Amparo
We happen to be professional wholesale dealer of jerseys, specialised in supplying Inexpensive Jerseys and custom-made jerseys. Jerseys with 100% stitched traditional quality, all Figures, Logos and Labels are sewn upon and embroidered. cheap 7 on 7 jerseys
Tue Oct 26 2021, 09:09 PM
Shavonne Dyke
Here are some of the items we currently pick, pack and ship for clients:
Mon Oct 25 2021, 04:40 PM
Willie Boser
Need more buyers for your site? We'll deliver niche targeted visitors in less than 24 hours: www.trafficpros.xyz
Mon Oct 25 2021, 03:33 PM
Bart Pfeifer
Here's 20 ways to get free web traffic from Google: https://ai6.net/Q7i5GH
Mon Oct 25 2021, 09:03 AM
Shermanviams
Clonevia

Downloads

Comments

Mirza123
Thu Jun 25 2020, 03:46 PM
eunicelove124
Mon Jun 22 2020, 03:03 PM
cerouno
Tue Jun 16 2020, 05:10 PM
Marce
Sat Jun 13 2020, 09:43 PM
Davidthils
Thu May 21 2020, 12:44 PM
Jakeror
Thu May 21 2020, 01:28 AM
motorCar
Wed May 20 2020, 07:05 PM
Vordrync
Wed May 20 2020, 11:52 AM

Online

Guests: 56, Members: 0 ...

most ever online: 182184
(Members: , Guests: 182184) on 06 Aug 2010: 05:37 AM

Members: 38215
Newest member: Mirza123