Getting Started with STM32 and Nucleo Part 6: Timers and Timer Interrupts | Digi-Key Electronics

In this tutorial, Shawn shows you how to set up timers in STM32 and use those timers to measure execution time, create non-blocking code, and trigger interrupts.
If you are not familiar with STM32CubeIDE, we recommend watching this video first: • Getting Started with S...
We first cover the basics of timers in STM32. A timer is a piece of hardware in the microcontroller that continually increments a stored value each clock pulse it receives. Most general purpose timers in microcontrollers are connected to the main CPU clock through one or more prescalers. A prescaler acts to divide the cock. For example, an 80 MHz clock that goes through a prescaler of 80 would cause a timer to increment (tick) at a rate of 1 MHz.
These timers can be used to trigger interrupts to run arbitrary code at given intervals, measure the time between events, or automatically control hardware, as in the case of output compare and pulse width modulation (PWM).
We show you how to configure a timer using STM32CubeIDE by setting a prescaler and a maximum counter value. When a timer reaches this maximum value, it will reset back to 0 (for our chosen general purpose timer).
From there, we create a demo using the STM32 HAL framework to first read timer values to measure execution time of another piece of code. Then, we show how to use timer values to create a non-blocking blink example. Finally, we set up a timer interrupt that triggers once per second. In the interrupt handler, we simply toggle the LED.
Please note that we are using the Nucleo-L476RG for this video, which can be found here: www.digikey.co...
Product Links:
Nucleo-L476RG - www.digikey.co...
Related Videos:
Getting Started with STM32 and Nucleo Part 1: Introduction to STM32CubeIDE and Blinky
• Getting Started with S...
Getting Started With STM32 and Nucleo Part 2: How to Use I2C to Read Temperature Sensor TMP102
• Getting Started With S...
Getting Started With STM32 & Nucleo Part 4: Working with ADC and DMA
• Getting Started With S...
Getting Started With STM32 and Nucleo Part 5: How to Use SPI
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Programming the Adafruit Feather STM32F405 Express with STM32CubeIDE
• Programming the Adafru...
TinyML: Getting Started with STM32 X-CUBE-AI
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Getting Started With STM32 and Nucleo Part 3: FreeRTOS - How To Run Multiple Threads w/ CMSIS-RTOS
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Related Project Links:
Getting Started with STM32 - Timers and Timer Interrupts - www.digikey.co...
Related Articles:
Getting Started with STM32 - How to Use SPI - www.digikey.co...
Making a Temperature Logger with the Adafruit Feather STM32F405 Express - www.digikey.co... -
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[@saravanaperumalannamalai3110]

Shawn, you structured it very well. 1hr Lecture shortened under 15 mins. Worth every sec spent on this video series.

[@gorillaau]

It's info dense, but easy to backtrack if you miss something. I'm enjoying this tutorial, while arranging the hardware.

[@Embedonix]

This engineer is the best in the business.... clear and concise and to the point! can not get any better!

[@kenwallace6493]

Shawn may actually make HAL useful to us bare-metal skeptics. He goes a mile-a-minute but one can always stop and replay. Great stuff!

[@ak17ism]

Thanks Shawn! These videos are awesome, hope to see more STM32 tutorials regardless of the subject! it may be a wormhole, but it'd be interesting to see a generic getting started with TFT display (TFT, SDRAM setup and where to go on the data sheet to find these)

[@yellowcrescent]

Nice! Also, if you don't need any of the timer functionality (like triggering ISRs/callbacks or toggling pins), an easy way to measure times to the nearest millisecond is to use HAL_GetTick(), although you may have to handle overflow cases for very long-running systems (overflow happens after ~49 days and it wraps back around to zero). This function is already setup in HAL_Init(), so no additional setup is necessary. uint32_t start_time = HAL_GetTick(); // do something uint32_t total_time = HAL_GetTick() - start_time; // total time elapsed in milliseconds

[@iro3d]

A very useful video. Though it would have been easier to watch if there were at least a 1000 milliseconds pause between sentences.

[@sixsunss8032]

Your tutorial is so clear for a beginner! Thanks so much!!! Please keep it in this style and hope to see more videos from you!!! (only one suggestion, the opening music is quite loud compared to the rest of the video)

[@thenoisyelectron]

Absolutely loving these STM32 tutorials! Thank you for putting time into these!

[@kiddjmadd]

Love the use of "sprintf!" Had my encoder (also a subset of timers) sending data, but I'd hit a wall trying to get a comprehensible value to the serial interface. Matching my code to the video confirmed encoder was working as expected without needing to mess with the raw hex that I'd been trying as a first pass.

[@hamedelahi2249]

Thank you so much for these videos. I saw the whole 6 videos. They are really excellent. Can you continue these videos? I will see all of them. And I also like to know about TFT LCDs and more other examples.

[@LOLWUT281]

Maybe Shawn knows but for everyone else, there's a built terminal in the STM program. Near the bottom right, on that 'console' tab if you lick the icon next to the pc monitor.

[@ShawnHymel]

I've played with it, and it seems to give me a console out of the IDE or to my PC. I couldn't ever seem to get it to give me a serial connection to my board, so I stuck with using an external program for that. I'd definitely love to know if there's a way to open a serial connection! Maybe I just missed something.

[@georgeborsa5346]

He's right. It works just as good as Putty. imgur.com/a/mfOAMig The "Arduino" named board is a Nucleo-G474RE.

[@ShawnHymel]

@@georgeborsa5346 Good to know, thanks!

[@timothynguyen4305]

Thanks Shawn for these videos! From a second year EE student :)

[@xptodundee]

Thanks for video - great series btw; in the interrupt case, I would "if (htim->Instance == TIM16)" which is an included definition in the HAL - this would make things more compatible should the viewers ever want to move that callback out of the main.c (without having to extern htim16 for example)

[@BEdmonson85]

Thanks for this, just what I was looking for...

[@goodwill7643]

Will wait for new series. Thank you!

[@bobesfanchi]

This was an excellent video. I was looking for the definition of callback function and I came across this video and learned a lot.

[@ephitous]

These videos are gold. Thanks!

[@anuragmahajan5919]

Thanks for the video!

[@electronichome1153]

Great course, Shawn, many thanks!

[@zetaconvex1987]

Very useful series. Thanks for these videos.

[@flexi1232]

first of all thank you for your videos, they are very helpful :) In this video at 9:44 u are saying that it also works if the timer rolls over zero. But if I run this code exactly the way u do it, this does not work... So I had to set the counter to zero after each second to avoid this. Did I make a mistake or how else should it work without this reset?

[@Schmalik]

Same thing happening to me. How can you reset the timer?

[@flexi1232]

@@Schmalik i used __HAL_TIM_SetCounter(&htim16, 0); to reset the timer to zero

[@MathewPanicker1010]

@@flexi1232 i was searching to see if anyone mentioned this! thanks

[@sdp8483]

These videos are super helpful. Thanks!

[@SurvivalSquirrel]

Keep up the good work!

[@jusroc6353]

what a great tutorial!

[@winstonsabellona2204]

thanks. i hope there will be more of this series about stm32 and nucleo dev board

[@mkashty1999]

This was an excellent video. Thanks a lot man!

[@coadi]

Great video. Maybe in the future you could also do one on RTC and sleep/stop/suspend. Thx again.

[@lucky716tw]

Amazing tutorial! Thank you very much

[@Manonsilvermountain]

Great video, and I'm learning a lot, but haven't forgot to show how to enable UART2 in configuration wizard, and what mode to choose?

[@younes2956]

Do you know to enable the UART2 in configuration

[@JerryHoward88]

This was really helpful!

[@FedericoSpada13]

Why if i set Period=0, timer doesn't run? I would like to generate an update event at every tick, which would require a Period=1-1, that would make sense... I know I can change the prescalar value to obtain the same update frequency but this "-1" is quite stupid...

[@noopursirmokadam7986]

Hi Shawn Hymel I am working on a simple implementation that checks each character being received using HAL_UART_Recieve_IT and when or is recieved it gets copied to another buffer. I have enabled USART as a global interrupt and wish to know how and where to use the Receive call back function. I am stuck and confused about this from a long time.

[@clivedsouza6213]

This dude rips.

[@victorgomez335]

I love these videos

[@seferideveloper6933]

Amazing tutorail

[@igabo95]

Great Video, thank you so much.

[@m-electronics5977]

Are existing other tutorials to make this only in CMSIS? Because learn the HAL with complete other names isn't productive when you had start with the CMSIS.

[@Bianchi77]

Nice video, keep it up, thank you :)

[@kenwallace6493]

This may be a dumb question but why don't we just use the timer rollover interrupt handler to write our LED toggle code? It would normally appear above main. What's the purpose of callback functions??

[@ArtemKanash]

perfect! Thanks a lot

[@nukulkhadse5253]

So do we take value of HCLK or APB1/APB2 Timer clock to prescale upto 1 MHz? Asking because you said if we change the mulplier and prescaler values of HCLK then we will have to consider different values.

[@bennguyen1313]

It's interesting that Timer's 'auto-reload preload' can be set to Disable, and you don't need to manually reload the counter in code! Regarding using a Timer for polling elapsed time, how does it differ from using HAL_GetTick(), i.e. no Timer? If using the Timer to trigger an ADC reading.. it seems the number of samples captured for an input sine-wave (single cycle), is dependent on the number of channels in the Scan. In other words, if NbrOfConversion=1, then the ADC will capture samples equal to the Timer rate.. but if NbrOfConversion>1, then only one channel gets converted per trigger event, the next channel in the scan list is captured only on the next trigger event? Speaking of Output-Compare, what does the "Pulse" field do? It seems it's necessary to be set to 1? For example, if Output-Compare is set to to Toggle on Match, with Trigger TRGO Event = Update , and if the Timer Clock is 120Mhz (Prescaler = 60-1, Preload 62-1), then the Ouput-Compare GPIO should toggle at 32khz.. so assuming one channel in the Scan list, how often will the ADC sample the channel?

[@mohammadhasanshokoohi7150]

Awesome

[@surendramaharjan3129]

Thank You!!! Please make a video on HAL Systick Timer.

[@abhishekkuksal5700]

Please add these 2 parts in your STM32 playlist!

[@samsman007]

Why Timer16 in the first place? Or could it just be any other timer?

[@RobertLugg]

Great stuff

[@mikes5025]

Thank you very much

[@jusroc6353]

Just a quick question on the subject. I am fairly new to Embedded electronics. I am planning to design a midi control surface that incorporates lots of rotary encoders on (as many as possible). I was wondering how I could ascertain how many GPIOs that have "attached" interrupts on them. Would be grateful for any advice here. Otherwise keep up the good work! thanks

[@emregngr8829]

I hope It will be continue

[@MrWATCHthisWAY]

I wasn’t aware of all the clock functions that were imbedded in this astm32. This will take awhile to grasp, and to find new applications. Just thinking about it hurts. 😔

[@ShawnHymel]

It's a lot! That's why I had to only focus on a few functions at once with the video. I still don't know how to use all of the features (or even what some of them mean!). One step at a time..learning how to measure time (such as milliseconds) is a good start :)

[@MrWATCHthisWAY]

Shawn Hymel - it May take a team!

[@Nithuigim1]

For the first example i am getting 5.6mS instead of 50mS , I am using a STM32F303K8T6 with 72Mhz clock and prescaler of 72-1 all others settings the same. ?!?

[@sidharthap]

what are callbacks and why are they called so?

[@ShawnHymel]

Callbacks are functions that you define in your code that are called from somewhere else (usually in a library or back-end). Often, a pointer to the function can be passed as an argument to that back-end code so that you can name the callback function whatever you want. It allows you to define a function and let something else call it, even if you don't know when that will be (they form the basis for event-driven programming). Here is a good example of how a callback might work in C: stackoverflow.com/questions/142789/what-is-a-callback-in-c-and-how-are-they-implemented

[@farvezfarook3422]

It would be nice to know how to register callbacks for individual timers

[@himanshujangra2599]

awesome video! can you please make a video on using stm32 as a usb HID device

[@Frisky0563]

Hi there is there a calculator for STM32 to help me figure out how to setup clocks, prescaler, multipliers output capture for 833.33 microseconds. I’m using the 476RG 106RG nucleo boards thank you.

[@AlexEduardoRR]

Thanks!!!

[@RenegadeFury]

At 10:00 this shouldn't work after a while right? If timer_val is 65,000, then __HAL_TIM_GET_COUNTER(&htim16) runs, this will give a value like 400, since it rolled over 400-65,000 >= 10,000 is false Unless maybe you do some casting, but then it will almost always be true You have to reset the timer, or have some extra logic

[@MathewPanicker1010]

indeed, you have to account for roll over manually, or reset counter to zero using __HAL_TIM_SET_COUNTER(&htim, 0);

[@adaminsanoff]

Why you left the variable "uart_buf_len" type int not uint16_t?

[@AlanAlan2001]

6:45 UART

[@Xsses]

Shawn, I think you forgot about digital inputs.

[@pancogito561]

Where is video about PWM???

[@JinFeeiLoh]

9:48 if (__HAL_TIM_GET_COUNTER(&htim16) - timer_val >= 10000)... isn't correct (missing cast). You need to do something like this: uint16_t tim16 = __HAL_TIM_GET_COUNTER(&htim16); if ((uint16_t)(tim16 - timer_val) >= 10000){ // ... do something timer_val = tim16; }

[@KR-pj6ol]

more videos please ........................................!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!........................................!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[@prachipatil3699]

Hi Digikey....can I have a sample of nucleo board from you 😊😊.

[@khanhluat8996]

.

[@talgtalga3767]

to much bla bla no examples for beginners as simple

[@mekbots7607]

you explaining really fast .relax mate .why you explain difficult