Has anyone know what is the difference between HAL_TIM_PWM_Start(),HAL_TIM_PWM_Start_IT() and HAL_TIM_PWM_Start_DMA()?

[Poulamee Sur]

Posted on June 27, 2018 at 13:25

Hello,

I am new in timer implementation , I want to generate PWM timer with an external clock using 2 MHz as frequency.. It shall be possible to enable or disable the generation of the PWM signal. I can able to generate, But I have a doubt for running the timer with support should give- blocking , DMA or interrupt ??

I have found three different function is available ,HAL_TIM_PWM_Start(),HAL_TIM_PWM_Start_IT() and HAL_TIM_PWM_Start_DMA() , What is the difference between these three ?? which is suitable for 2Mhz PWM timer generation and why ?

I'm using STM32F7 Nucleo Board

Any help would be appreciated.

Thanks in advance.

[Imen.D]

Posted on June 28, 2018 at 12:36

Hello

sur.poulamee@in.bosch.com

, 

Can you please precise if you want to put the 2MHz frequency signal as an input clock source for timer 

or generate PWM timer signal with 2 MHz frequency? If it is possible provide a figure that explain your expected configuration.

If you just want generate a PWM signal, you can use the HAL_TIM_PWM_Start function.

For HAL_TIM_PWM_Start() funtion: 

Starts the PWM signal generation.

The HAL_TIM_PWM_Start_IT() funtion s

tarts the PWM signal with interrupt generation.

 

HAL_TIM_PWM_Start_DMA() funtion s

tarts the TIM PWM signal with DMA request generation.

You can refer to the

https://www.st.com/content/ccc/resource/technical/document/application_note/54/0f/67/eb/47/34/45/40/DM00042534.pdf/files/DM00042534.pdf/jcr:content/translations/en.DM00042534.pdf

 it can help you to understand the PWM generation signal.

I recommend you to start from the TIM_PWMOutput example within the

https://www.st.com/content/st_com/en/products/embedded-software/mcus-embedded-software/stm32-embedded-software/stm32cube-mcu-packages/stm32cubef7.html

firmware package examples

STM32Cube_FW_F7_V1.11.0\Projects\STM32F746ZG-Nucleo\Examples\TIM\TIM_PWMOutput

With Regards,

Imen

[henry.dick]

Posted on June 28, 2018 at 13:03

'

I want to generate PWM timer with an external clock using 2 MHz as frequency.. '

2Mhz PWM frequency would be nuts, most of the times.

'But I have a doubt for running the timer with support should give- blocking , DMA or interrupt ??'

does HAL come with any documentation? if not, read the code / examples and compare it to datasheet to see how it works.

[Poulamee Sur]

Posted on June 28, 2018 at 13:45

Hello

DAHMEN.IMEN

Thank you for your reply , the timer should generate 2 MHz frequency.

If I go with polling method, It will be block the CPU or something else??

Do you have any idea on that ?

[Imen.D]

Posted on June 28, 2018 at 14:45

Hi 

sur.poulamee

 ,

The CPU cannot be blocked by the timer and to generate the 2MHz frequency, you should apply this equation:

Where:

TIM_CLK = timer clock input

PSC = 16-bit prescaler register

ARR = 16/32-bit Autoreload register

I suggest you to use STM32CubeMx tool, which help you to develop your Timer application with easy configuration and generate an initialization code.

WIth Regards,

Imen