STM32 TIMERS #4. INPUT CAPTURE || Frequency and Width

[@Engrbilal143]

Appreciate your effort for providing such high quality tutorials for free

[@PaulSanders-n5o]

Thanks for a great video, I added an overflow IRQ to sample very slow frequencies on the same counter. Also I added a flag once a conversion is ready to calculate and stopped the edge IRQ, so this lets you push the measurement range a bit high if you are looking at constant frequencies.

[@bobby9568]

This guy is smarter than my professor!

[@LinusLee-pg1uu]

Thank you for the video! But I have a question: is timer 1 and timer 2 physically connected? How can timer2 receive the pwm input from timer1? and why would HAL_TIM_IC_CaptureCallback trigged by timer1? I thought AL_TIM_IC_CaptureCallback is triggered by input, but timer1 is output. Thank you very much again!

[@ControllersTech]

Yes timer1's output is connected to the timer2's pin. Ic capture callback is not triggered by tim1, its triggered by tim2

[@LinusLee-pg1uu]

@@ControllersTech Thank you, now I understand!

[@roy_hawk]

Hello friend! I wanted to ask you a question. You know that IC (Input Capture) function that we use in timers? I generally saw that it is used to read frequency, I have already tested it for this purpose too and it works well. But one thing that I was never able to do using the IC in that mode that activates the interrupt by rising and falling edges, was to have information whether the interrupt was activated by a rising edge or a falling edge. And a while ago I searched everywhere, I did a lot of tests, apparently a flag was supposed to be set according to the edge that activated it, but it was never set. In fact, I tested this a lot and ended up thinking that it is impossible, which for me is absurd, considering that the information is there, but it seems inaccessible. Having said that, please, is it possible to use the IC with interruption on both edges (rising and falling) and be able to identify the edge? For example, if it was a rising edge, I want to enter an if, if it was a falling edge, I want to enter another if (or else). I really wanted it to be possible, thinking about an application to check synchrony between square waves and the difference in angle between them. If it's not possible, then I'll do it with a timer and perhaps external interruption, but I wanted to use the IC for precision. I would be very grateful if you could clarify whether it is possible or not. Thanks!

[@sarathm3972]

I am using the stm32h745-nucleo board. Currently I am Working with the timers. As I am working with the timers I need one timer in the cm4 and another timer in the cm7. I need to capture the falling edge of timer cm7 and need to give input for cm4 timer. Could you please help me out to find the falling edge for cm7 timer pulse to achieve this.

[@martinchristiansson658]

Plaese do a video on i2c with dma..trying this with mpu6050 and no succes at the moment

[@labamichnetvoll5911]

hi, nice videos, could you make a tutorial about dmx timing via uart for stm32 ?

[@yasinbyker]

I want to measure the rpm of an engine. Using the information in this video, can the rpm of an engine be measured with the help of a sensor(like fc-33)? If it can be measured, how should I proceed?

[@mrdoo201]

Hi sir, thanks for your video. But I have some confusing in this video and can you help me to explain one thing ? In your video, you configed Timer 1 is PWM output and Timer 2 is Input Capture. But when you caculate refClock at 6:42, why you use TIMECLOCK and PRESCALAR of Timer 2 ? The Frequency after that is the frequency of PWM Timer 1 so I think the TIMECLOCK and PRESCALAR is Timer 1 too. I'm just a newbie and thank you so much.

[@ControllersTech]

The TIMCLOCK and PRESCALAR is used for calculating the input frequency. Basically we capture the counter value of timer2 for 2 triigers. Then we find the difference in the counter values and this difference is equivalent to the input frequency. But here we need to convert the difference we got, to the frequency or time equivalent. To do so, we need to know at what rate our counter is running. That's why we use the clock of tim2. For eg- if counter is running at 1000hz, then the difference of 10 means the frequency is 100hz. And if the counter is running at 1MHz, then the same difference of 10 means the freq is 100khz. So it depends on the counter rate and hence we use the values of the timer, which is actually capturing.

[@UTubeJamesChou]

Thank you so much. I have a question, how can I confirm that the first incoming interrupt is triggered by a rising edge and the second interrupt is generated by a falling edge? From what I see here, the entire period is 100 clocks, and the pulse width is 30. Most of the time, I get a difference result of 70, but sometimes after a while it becomes 30. It looks like the first interrupt is generated by a falling edge, while the second interrupt is generated by a rising edge.

[@ControllersTech]

You can first only enable the rising edge interrupt. Once it is detected and callback is called, enable falling edge also.

[@MrItsfitz]

Thanks for the really informative and clear set of STM32 timer tutorials. However, I just cannot get this IC set up working. I'm using a Blue Pill board in the STM32CubeIDE and the debugger message "(Suspended : Signal ; SIGTRAP/Trace/breakpoint trap)" is displayed. The PWM is being generated and there are no breakpoints set. Can you help?

[@ControllersTech]

I don't know about this. Never faced such issue

[@himjan929]

Faced similar problem, My error was divide by zero. I was dividing a number by zero due to poor initialization.

[@incxxxx]

You should connect PA8 and PA0, to provide signał which makes interupt. That important fact is not mentioned in the film.

[@incxxxx]

You should connect PA8 and PA0, to provide signał which makes interupt. That important fact is not mentioned in the film.

[@ulisesferreira4862]

Thank you so much for the help. I understood a lot of things and configurations that i didn't in class. However im having trouble with the measurement of frequency, i do have the pins A0 and A8 connected but the live expression frequency stays at cero.

[@berlinraj8149]

bro same issues bro.. can you solve this ?

[@zainalishammat2866]

thank you very much :)

[@bennguyen1313]

At the 1m45s mark that shows the block diagram.. where does it say that Timer1 PWM Output can be used as the input to Timer2 Input-Capture? For example, in the RM it says the input signal to measure (IC4) via Input-Capture reg is selected (ICSELECTION) in TIM2_CCMR2 as : TI4 (b01-Direct), TI3 (b10-Other Channel3), or TRC(b11) Where does it say that TI4 is not the input pin, but rather Timer 1's Output PWM?

[@ControllersTech]

I am feeding it manually. We need some signal to test the IC right, the signal come from the output of another timer.

[@ramzibrik6845]

Hi. How i can measure the frequency of sine wave ?

[@andreichichak5242]

A sine wave will be squared up by the schmidt-trigger input of the processor. Externally it will be a sine wave, but the processor will see a square wave.

[@afiziadebisi7909]

If I’m taking input from an external wave generator do I just connect it to one of the timers

[@ControllersTech]

Yes ofcourse

[@medraouf819]

does this code work if i wanted to count the number of pulses of a high speed rolling theeth gear? (every tooth gives a pulse)

[@mmt1024]

What if falling edge will appear first, then you will measure width between falling and rising, so 80% ?

[@ControllersTech]

Haha right. Actually we can do something about it, but i didn't included that part. Or else the code would be a bit complicated.. Anyway like i said i will release another video using DMA, and such things are taken care in it..

[@najidjalees4321]

can we get any frequency value if we dont give any input signal to the microcontroller?

[@dimaabualfoul9281]

TYSM ! CRYSTAL CLEAR

[@alexandrev.3332]

Very nice, this worked very well

[@sugiyartosugiyarto1587]

Thank sir

[@YogeshJagtap-f1z]

My board is STM32 Discovery board so in that case what settings I should do to get output . I have done all settings according to your video but still I am not getting the output frequency.Kindly tell me the hardware settings also

[@incxxxx]

You should connect PA8 and PA0, to provide signał which makes interupt. That important fact is not mentioned in the film.

[@truongho2771]

Hi , mFactor = 1000000/refClock I dont understand , can you help me ?

[@Shet_does]

Hello If i need to use timer input capture for capturing both rising and falling of a tounch sensor And i need to check whether the difference is equal or greater than 5sec if so i need to execute respective tasks how can i do that for 16 bit timer I configured for 1ms configuration It will be long pulse where several counter roll out would happen how to do this basically how can we have condition to check for whether greater than 5sec at the moment i release

[@ControllersTech]

You should use external interrupt for this. Set the interrupt to both rising and falling edges. Define a 32 bit variable in the main file and desfine it as an external variable in the interrupt.c file. Increment the variable in the systick handler. When the interrupt is triggerd due to rising edge, reset the varibale. And when it is triggered due to falling edge, measure its value.

[@Shet_does]

Can you please give some more insight currently interrupt for rising and falling edge is configured.

[@mohamedalikhlifi9045]

sir i tried to measure the frequency but Always the live expression show 50, can you help me

[@akashv5622]

This seems quite absurd, how can we actually infer that timer 1 and 2 are connected.. There has to be some setting to explain this right? What if there are a lot of timers enabled how will that timer get to know to capture which timer signal

[@akashv5622]

I don't think so the timers are connected internally by default.. I used a jumper to connect both the pins and now the interuppt started triggering. I'm using a stm32g474-dpow board

[@furkanyaprakcer844]

what we can do for 100% duty cycle situations?

[@ControllersTech]

Nothing

[@ARM_TECH]

Project with low pass filter witch agian

[@ARM_TECH]

Thanks

[@harishkumar-sf9km]

I want configuration and code using input capture for hc-sr04 sensor with stm32f446re mcu

[@ControllersTech]

Its already present on the channel. Atleast search for things before asking about it. kzbin.info/www/bejne/qprCYo2th9Sfi5Y

[@Red_Fang.]

i want to ask, how to use this feature for applying long pressed push button ? anyone have the source code or any references ? thank you

[@ControllersTech]

Lets assume the pulse goes high when you press the button and low when you release it. Just measure the width between the high and low pulse. Then program your controller as per that width. If (width > 300ms) then long press triggered.

[@Embedded_Developer]

wonderfull!

[@ferdinvivian9336]

Is this live class sir

[@ControllersTech]

No. It's just premiere..

[@ferdinvivian9336]

@@ControllersTech thanks a lot for your valuable videos sir. Thanks for your efforts

[@truongho2771]

why did you use CLOCK SOURE : INTERNAL CLOCK , because you use RCC: CRYSTAL and Config you use HSE

[@ControllersTech]

What time ? Point the timeline

[@truongho2771]

@@ControllersTech it 2:57 you choose INTERNAL CLOCK, but CLOCK CONFIG you use HSE

[@ControllersTech]

Thats the clock for the timer. It is clocked by the APB clock.

[@truongho2771]

@@ControllersTech i know , but when we use Timer always choose INTERNAL CLOCK ? , beacause i dont use INTERNAL CLOCK it no problem

[@ControllersTech]

Vhoosing the type of clock changes the timer operation mode. You can read more about it in the reference manual of your controller