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Latest Projects Education. JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding. How to program a delay in assembly? Search Forums New Posts. Hello, I am programming microcotroller in assembly and I'm trying to stop the program for 10 seconds and then continue with the rest of the program.

Any ideas on how to do this?

program to call a delay subroutine

Scroll to continue with content. One classic way to make a delay is to use nested decrement loops. Every time the inner loop counts down to 0, then the next decrements, and so on. It's a bit tedious to adjust the timing, and interrupts will mess with the process, but it works.

Ratch Joined Mar 20, 1, MLCC, I am programming microcotroller in assembly and I'm trying to stop the program for 10 seconds and then continue with the rest of the program. The Loop is what seems to do the trick, although, is their a more efficient way to do this? I need a example with it too, I'm very new to programming microcontrollers. MLCC said:. Mark44 Joined Nov 26, It would take more than a couple of NOP instructions to wait 10 seconds, and the number needed would depend on the clock speed of the microcontroller, and how long it takes to process a NOP.

You must log in or register to reply here. You May Also Like. Continue to site.Thus a time delay of any magnitude can be generated by looping suitable instructions a required number of time. Any way, keep one thing in mind that software delay is not very accurate because we cannot exactly predict how much time its takes for executing a single instruction. The above program roughly produces a delay of 1mS. The program is written as a subroutine and it works this way.

You can make adjustments on the initial values of R6 and R7 to make the result more accurate. In this program subroutine for delaying 1mS DELAY is called 4 times back to back and the entire cycle is repeated times. Using software delay subroutines square waves over a wide frequency range limited by the crystal frequency can be produced using This will result in a square wave of the required frequency at the corresponding port pin.

Circuit diagram for generating square wave using is shown below. The same circuit can be used for generating any frequency but the program is different. Hey everyone,i am trying to make a seven segment based digital clock with time set feature using controller,i am having trouble in software part of this circuit,can anyone giva me some help regarding hex code for this circuit….

Hi every body I am one of them whoes are mad in harware programming so if u read this message please reply if send ur anu email or chatting room adress. Software delay routine in square wave generator using Author admin. Akshay Sorathiya 6 years ago. Plzzzz Help…. Submit Type above and press Enter to search. Press Esc to cancel.This worksheet makes use of several examples programs that are all available for download from this website.

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The program sets up some arrays and then outputs them. At three stages in the program boldedit asks whether it should continue; it stops if the answer is not 'y'. Notice that the three bolded parts of the code are identical.

Simple enough — but look at the amount of code! Most of it is the same — wouldn't it be nice to re-use the code and cut down on the typing? The answer is to use subroutines. The program is much easier to understand now. All the code for prompting is in one place. If we ever need to change the code which prompts the user to continue, we will only ever need to change it once. This makes the program more maintainable.

We have seen that subroutines are very useful where we need to execute the same bit of code repeatedly. The subroutine can be thought of as a separate program which we can call on whenever we wish to do a specific task. It is independent of the main program — it knows nothing about the variables used in the main program. Also, the main program knows nothing about the variables used in the subroutine.

This can be useful — we can write a subroutine using any variable names we wish and we know that they will not interfere with anything we have already set up in the main program.

This immediately poses a problem — what if we want the subroutine to do calculations for us that we can use in the main program? The values, rad1 and vol1 are passed to the subroutine. The subroutine calculates a value for the volume and when the line :.

Write a program that calculates the difference in area between two triangles. Your program should prompt the user for the information it needs to do the calculation. Use a subroutine to calculate the actual area. Pass information to the subroutine using arguments.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. My problem is that I have written a code that is supposed to output a result into a set of LEDs connected to the parallel port. When I ran the code it pretty much did nothing. My instructor told me that the code ran too fast that my eyes did not see what happened. I have found that there are a couple of ways to do a time delay, I have tried to loop the NOP but I think I cannot really determine what is going on.

Is there any better way? Waits a specified number of microseconds before returning control to the caller. So to wait approximately 1 second using this method you'd execute this interrupt function once, save CX:DX in a variable, then execute the same interrupt in a loop until the absolute value of CX:DX - firstCX:DX is greater than I used two registers which I set them both to any high value and its gonna keep on looping until both values go to zero. Alternatively, you can create a process and call it every time you want to delay using only the counter register and stack implementation.

How to program a delay in assembly?

Learn more. How to set 1 second time delay at assembly language Ask Question. Asked 7 years, 1 month ago. Active 1 year ago.

program to call a delay subroutine

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program to call a delay subroutine

Jer Yango Jer Yango 2 2 gold badges 6 6 silver badges 15 15 bronze badges. This typically requires an OS or BIOS call, or knowing the CPU's clock frequency and very carefully constructing a loop that will delay for the proper number of cycles and assuming that the clock frequency doesn't change. What operating system are you doing this on? The best way, if you have the hardware, is to use a dedicated timer to do the timing. It will then notify the CPU through an interrupt when the delay has expired.

This allows the CPU to do other work while waiting, which is often very nice. Jim Mischel Hi, i am using a windows xp in running the code. Building the code was on an emulator. Will the NOP loop be able to do this? I am planning to loop it at a certain time, but i don't know how many cycles each instruction is done.Pages: [1] 2.

Topic: How to work with subroutines?

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Read times previous topic - next topic. Zoandar Guest. How to work with subroutines? I have been doing some research for a couple hours and just can't seem to find the 'simple' answer to a seemingly simple question, so perhaps someone can help me please? I am still new to Arduino and would like to create a sketch that uses subroutines.

I sort of remember how I did that years ago in Basic, but I can't find the right terminology for how to do it in the code Arduino uses.

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I want to do something like this, but I need to know how to translate these terms into Arduino's code how to name a subroutine, how to call a subroutine, etc. It doesn't seem to be covered in the Reference section of the Arduino. Code: [Select]. Re: How to work with subroutines?

Thanks for the quick reply, but that is one of the pages I read during my research, and it just confused me more than helped. The term "int" is described in the Reference guide as defining an integer. They do not make any reference to it naming a subroutine. Yet on that page you are suggesting, it "seems" they are using "int" to name the function "myMultiplyFunction", and they are also passing variables in that same line of code.

This is far more complex than what I am trying to do, so I don't understand it. Then, in place of "Gosub Step 1" would I just use: Step 1; to go to that block of code? If it is that simple I guess I missed it, and if it is not that simple I am also missing what else I would need to do. As I understand it you can call a subroutine simply by writing "subroutinename ". Example code would be as follows Code: [Select].

Thanks guys! I have this working now: Code: [Select]. Just a minor point. In the two functions you defined, you have a return; as the last statement in both. As both those functions are defined as void functions meaning they don't return any value you do not require that return; statement.

Arduino Workshop - Chapter Three - Creating Functions

It does no harm with them there in a void function, but both functions will end properly without it and it might mislead you later at sometime when reading over your code. Notice that the standard arduino void startup function has no return; statement at it's end. Thanks Lefty. I actually had to scratch my head a bit on those returns.

I am used to always using a Return back my Basic coding days decades ago, so I figured I needed them for sure.

However, the first mistake I made was in using "Return ;" - Apparently when not using the parameters during the declaration of the subroutine, seeing those " " at the Return point was failing the verification.

But I couldn't figure out why. So I went back and read in the Resource page for the Return command that it was also acceptable to just put "Return;" if the parameters were not being used.

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I then pulled the " " out, and the program verified OK.Subroutines are used if you are performing the same function more than once, for example creating a delay.

The advantages of using a subroutine are that it will be easier to alter the value once inside a subroutine rather than, say, ten times throughout your program, and also it help s to reduce the amount of memory your program occupies inside the PIC. We then type the code that we want to perform as normal. In this case, We have chosen the delay in our flashing led program. To start the subroutine from anywhere in our program, we simply type the instruction CALL followed by the subroutine name.

Let us look at this in slightly more detail. When we reach the part of our program that says CALL xxx, where xxx is the name of our subroutine, the program jumps to wherever the subroutine xxx resides. The instructions inside the subroutine are carried out. You can call the same subroutine as many times as you want, which is why using subroutines reduce s the overall length of our program.

However, there are two thin g s you should be aware of. First, as in our main program, any constants must be declared before they are used. These can be either declared within the subroutine itself, or right at the start of the main program. We would recommend that you declare everything at the start of your main program, as then you know that everything is in the same place. Secondly, you must ensure that the main program skips over the subroutine. The PIC does not differentiate between a subroutine and the main program.

Let us look at our flashing led program, but this time we will use a subroutine for the delay loop. Hopefully, you will see how much simpler the program looks, and also you will see how the subroutine works for real. Hopefully, you can see that by using a subroutine for our delay loop, we have reduced the size of the program.

Each time we want a delay, either when the LED is on or off, we simply call the delay subroutine. In the example above, we turn the LED on. We then call the subroutine.

Subroutines and Functions

The program then returns so that we can turn the LED off. For those of you who are interested, our original program was bytes long.

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By using the subroutine, we have reduced our program size down to bytes. This may not seem to be that great, but seeing that we only have bytes in total inside the PIC, every little bit helps. Engineering Hobby Projects. Engineering Projects. Subroutines A subroutine is a section of code, or program, than can be called as and when you need it. In the next tutorial, we will look at reading from the ports. Note: To report broken links or to submit your projects please send email to Webmaster.If you've completed the 4-bit counter on the previous pageyou'll know that we used a pre-written subroutine, and that we didn't look at the contents of this subroutine.

Even at this early stage, we were using "modular programming". You'll find that as you write more code, you'll start to re-use bits of code for common applications and before long, you'll have your own "software library" to call on. However, it's important to understand the time delays, and as we explain them, some new, important topics will be introduced. We'll examine the first option here. There is an obvious problem with it - while sitting in a loop, the processor can not do anything else, and for some applications, this is unacceptable.

Option 2 might allow a solution to this, but it's one for later! First, consider how quickly the processor runs. Depending on what version you buy, a mid-range PIC can run up to 20MHz - check the suffix in the part number for the highest speed applicable.

As you might expect, the faster versions are more expensive, but not prohibitively so. Note that these processors can run at any speed you require up to the rated speed. So, there's nothing stopping you running the processor at 1Hz if you want! If you have a variable frequency square-wave generator, you can use it as the clock - from an educational point of view, this is something to try when your PIC is running the 4 bit counter.

This is possible because the internal memory of the PICs uses static memory technology as opposed to dynamic memory, that must be "refreshed" frequently for reliable operation. The clock is divided by 4 which allows the internal "pipelining" to workso a 4MHz crystal will result in an internal CPU running at 1MHz.

This means that the clock cycle lasts 1 microsecond. Thanks to the highly optimised core, the CPU is able to execute most instructions in just one clock cycle, so each line of your code will execute in just 1 microsecond.

This also explains why 4MHz is a popular choice of clock frequency. When I wrote these routines, I decided to build in as much flexibility as possible. So, I wrote a subroutine that would take exactly 1 millisecond to execute - I then reasoned that I could call this N times when I required a subroutine of N ms.

In contrast to the last section, I've provided you with written code, and the exercise now is to try and understand it This short snippet of code is rather more complicated than it first appears, so lets begin with a simple explanation. The "entry point" is the first line, so by inserting call Wait1ms into your code, a 1ms delay is invoked. Note the label 2 lines down - this is effectively an "internal" label - my convention is to write "entry point" labels in mixed case, and "internal" labels in lower case.

Feel free to choose your own method This subroutine works entirely with the working register - no other variables are required. It starts by loading into W, and decrementing W until it equals zero.

This is detected by the btfss statement. I should say that I found the starting value empirically, so this routine might not be exactly accurate! Why are we decrimenting the W register? Well, it's much easier this way - we could count up, just like the 4 bit counter did, but we would need all the extra lines needed to do the XOR comparison. This version is more code-efficientimportant because programme memory is limited.

Note also that, referring to the instruction setyou'll see that there are no instructions to directly decrement or increment the working register, hence the use of addlw. The curious part of the routine is the addlw d''which is supposed to decrement the working register.

There are two questions that should spring to mind - first, how does that work, and second, why not use sublw d'1'? We will answer the second question in more detail later, but suffice to say at this point, the subtracting instructions don't work exactly as you might expect. Let's deal with the first question - how does adding to a number actually reduce it by one?

It's basically because of the magic of binary numbers. Data memory in the PICs is 8 bits wide.


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Program to call a delay subroutine
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