Discussion in "8051 Discussion Forum" started by    cenadius    Oct 4, 2007.
Thu Oct 04 2007, 09:44 PM
#1
ajay,give me the example on how to write delay assembly code by using both method,timer and register,thanks
Fri Oct 05 2007, 06:17 AM
#2
In timers... there are few things to take care of.. first.. amount of time you want delay for, second which timer mode is suitable for that delay.
Timer increment a count every single machine cycle. so if you are using a clock of say.. 12Mhz then.. no. of times timer count is incremented is:
12000000/12 = 1000000
i.e. timer will be incremented 1,000,000 times in a sec.
Lets say you want a delay of 10mS (0.01S)
and you have to calculate the count which is to be loaded in Timer registers (THx and TLx) to find the count to be loaded.. simply multiply the required delay with the count per sec..
i.e. 0.01 x 1,000,000 = 10,000
so we need to count from 0 to 10,000. Maximum count for 16 bit timer is 65536. So if we load 65536-10000 = 55536 in timer registers it till automatically count 10000 times..
So final value is 55536 (DF80H)
so THx = DFH and TLx = 80H
this will give you the required delay...

in case of registers.. you need to add all the time delay required for an instruction to execute and then multiply it by the loop count.. that will give you the time delay..
e.g. the commonly used instructions in register delay are.. djnz Rx,label (2 machine cycles)
loading value using MOV instruction also need 2 machine cycles. RET instuction and Acall instuction both need 2 machine cycles.
Lets say you want a delay of 100uS then.. you are running a clock of 12Mhz, so 1 machine cycle will be of 1uS. you can divide this according to the instructions as...
100 - 2(RET) - 2(lcall) - 2 (load) = 94uS left
94/2 (for DJNZ) = 47 (the count)

so required loop for 100uS delay is..

delay100uS:
      mov R7,#47
wait:
      djnz r7,wait
      ret
 youth69shaikmajoka like this.
Tags 8051 time delaytime delay calculationdelay using timersdelay using registers8051 timers
Sat Oct 06 2007, 04:56 AM
#3
ok,thanks,i need this in my exam,thanks for ur explaination :-)
Fri Apr 15 2011, 03:29 PM
#4
wow ajay! Nice explaination <3
Sat Apr 16 2011, 08:50 AM
#5
you can also use this simple program to help you in delay with assembly code from here
Mon Apr 18 2011, 08:20 PM
#6
@MAAM this program is also available here on website

Get Social

Information

Powered by e107 Forum System

Conversation

Thu Nov 21 2019, 12:30 PM
raj2555
how to interface 8051 microcontroller with NRF24L01+ module
ExperimenterUK
Sat Oct 12 2019, 10:23 PM
Log in.. then post your code in the 8051 forum
Sat Oct 12 2019, 10:18 AM
Bhadra Sajikumar
i am doing a countdown timer with 8051 for my project, unfortunately our professor had to take a leave of absence before he could teach us most of it.. can someone explain the .asm code of it for me?
Mon Sep 23 2019, 07:37 AM
Nathaniel
I am doing a project for my schools wireless security system with cameras,sensors and spot lights using 8051 micro controller, could you help me out with the design and its source code.
Wed Sep 18 2019, 08:48 PM
Caryn Kover
Thank you for your time,
ExperimenterUK
Mon Aug 05 2019, 07:09 PM
@Ismail ..post in forum, give details
Mon Aug 05 2019, 04:33 PM
Ismail balghmi
Hello. Please I won't download
ExperimenterUK
Wed Jul 24 2019, 12:47 AM
@BUSTER123 Please post in the forum
Tue Jul 23 2019, 06:13 PM
BUSTER123
hello! newbie here. i am kind of a guy who hates using ready - made existing libraries, so this helped a lot as i was trying to control and write to a character lcd display. however, i can't figure out how to set the cursor position. for example, i want to set it to the 5th column in the first row, so position 5. so according to the table, i am sending 10000101 on the 8 data lines of the lcd (register select pulled low). the cursor does not move there however. and i cant move the cursor left or right too. is it something wrong that i am doing? thank you.
ExperimenterUK
Thu Jul 11 2019, 07:55 PM
@ramos https://www.theengineeringprojects.com/2017/09/l298-motor-driver-library-proteus.html

Downloads

Comments

Istika
Thu Dec 12 2019, 12:04 PM
nabiha_anaya
Sun Dec 08 2019, 09:16 AM
ananyagupta
Tue Dec 03 2019, 07:53 AM
wells
Mon Nov 25 2019, 08:25 PM
auwal
Tue Nov 19 2019, 03:13 PM
ANKITPATEL
Mon Nov 18 2019, 11:00 AM
Casmir
Wed Nov 13 2019, 06:25 AM
DeepakBGattani
Mon Nov 11 2019, 01:31 PM

Online

Guests: 68, Members: 0 ...

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

Members: 38109
Newest member: Istika
Forum Activity
ilylily07 Avatar
Posted By ilylily07
Thu Dec 12 2019, 02:26 PM
wil do.thank you for your advice!
ExperimenterUK Avatar
Posted By ExperimenterUK
Thu Dec 12 2019, 07:13 AM
Something like this ?https://www.bing.com/videos/s...
ExperimenterUK Avatar
Posted By ExperimenterUK
Thu Dec 12 2019, 06:58 AM
The layout is a bit different, but it is the same ...
ilylily07 Avatar
Posted By ilylily07
Thu Dec 12 2019, 04:38 AM
https://i.imgur.com/6S5FcwF.png right now im follo...
ExperimenterUK Avatar
Posted By ExperimenterUK
Tue Dec 10 2019, 04:49 PM
ilylily07 Avatar
Posted By ilylily07
Sun Dec 08 2019, 01:24 PM
Hi .im humbly ask for your advice as i wrongly pur...
nabiha_anaya Avatar
Posted By nabiha_anaya
Sun Dec 08 2019, 09:19 AM
My teacher assign me a project on "voice control h...
ExperimenterUK Avatar
Posted By ExperimenterUK
Fri Nov 29 2019, 04:24 AM
" Is it possible to interface a fingerprint scanne...
ilylily07 Avatar
Posted By ilylily07
Thu Nov 28 2019, 03:50 PM
You will not find any code for an 8051 as no one w...
ExperimenterUK Avatar
Posted By ExperimenterUK
Tue Nov 26 2019, 05:44 PM
You will not find any code for an 8051 as no one w...