#SIMPLE DELAY FUNCTION FOR 8051 IN C PORTABLE#
#SIMPLE DELAY FUNCTION FOR 8051 IN C SOFTWARE#
#SIMPLE DELAY FUNCTION FOR 8051 IN C CODE#

Timers in different mode of operations are configured by special function registers. Timers in a microcontroller are controlled by the SFRs (Special Function Registers). Timers on the other hand are used to generate delays. The value of the counter is incremented by 1 when an action or an event occurs. These timers are not only used for generating time delay but also used for counting purpose. Most of the controllers have inbuilt timers. Steps for generating precise Delay using 8051 Timers.

#SIMPLE DELAY FUNCTION FOR 8051 IN C CODE#

At the end of the day though, there are certainly several mechanisms that can help to delay code execution by a defined time period. Developers can then decide how sophisticated a solution they want to use.

#SIMPLE DELAY FUNCTION FOR 8051 IN C SOFTWARE#

The technique that is used will depend on the software and hardware resources available in the system. Techniques similar to those shown in technique #2 and technique #3 can then be used with those soft timers to create a delay in the code execution.Īs we have seen in today’s post, there are several different techniques that are available to developers who want to delay their codes execution. These are software-based timers that are triggered from a running hardware timer. Related to the RTOS objects is that most RTOS’s also include soft timers. This delay time can be used to cause a delay in the application as well. If you carefully look at the API’s for objects such as semaphores, mutexes and queues within your favorite RTOS, you’ll notice that most API calls that wait will also include a delay time. The last technique that we will discuss today is the use of other RTOS objects to delay time. There may be a problem with using a delay mechanism like this because the task will yield the CPU for that period but there is no guarantee that the task will be the highest priority task once the system tick period has expired! The task will only run immediately after the delay if the task is the highest priority task that is ready to run so there could be some jitter to the delay time. The RTOS tick may be set to one millisecond or ten depending on the configuration. This delay function will cause the task to yield the current task for one RTOS tick. Developers can leverage this to create a delay similar to the following: The system usually employs some API that allows a developer to access the current system tick such as SysTick_Get(). Usually these system ticks are set to occur every 1 or 10 milliseconds in a typical system.

Even bare-metal systems usually have a background timer that acts as a system tick so that the software has a time reference from the moment the microcontroller has started. In these circumstances, developers can leverage an onboard system tick to create the delay. There may be instances where a dedicated hardware timer is not available or setting up a one-shot timer is undesirable. Technique #3 – Use a system tick (HAL Example) In fact, the API can be reused through-out the code to allow a single timer to be used for any number of delays that are required.

#SIMPLE DELAY FUNCTION FOR 8051 IN C PORTABLE#

It’s also more portable and can be more easily tuned for the desired delay period. This technique is much more robust than the conditional loop we looked at earlier. The code would start the timer and wait for the timer overflow flag to be set which would then indicate that the time has elapsed.Īn abstracted version of this code could look something like the following: In this instance, the timer would be setup as a one-shot timer. If a developer needs a delay such as 10 microseconds, a hardware timer could be loaded with the count value that would represent 10 microseconds. There are often several different hardware timers that can be used to keep track of system time, generate waveforms, capture inputs and general purpose. These timing loops are just too unpredictable for use in any production code.Ī second technique that can be used is to leverage a hardware timer built into the microcontroller.

Plus, there is always a question about how much of a delay is that really? One might think it’s 100,000 instructions but each time through the loop there will be additional instructions to check the loop variables and increment i.

If a developer were to adjust the clock frequency for a different operational mode such as low power operation, the delay time will be completely different.

Dick Jarrett on 5 Strategies for Minimizing Debug TimeĪ conditional delay can be useful in a pinch but it’s hardly accurate or effective.

Jacob Beningo on 5 Strategies for Minimizing Debug Time.

moredatalesscenter on 5 Strategies for Minimizing Debug Time.

Matteo Borghesi on 3 Tips for Data-Centric Software Design.

Jacob Beningo on 3 Tips for Data-Centric Software Design.

Simple delay function for 8051 in c