STM32F103C8 Generating different frequencies and duty in same timer on different channels

[Rajesh3]

Hi,

I'm a beginner in embedded systems.

I'm trying out one thing that is I want to generate two different frequencies (100hz & 10hz) with both at 50% duty on TIMER 4 CH1 PWM Generation and TIMER 4 CH2 PWM Generation . Whether it is possible to generate different frequencies in same timer or is there any other method to generate it in STM32F103C8 blue pill kindly help me I'm stuck.

[Andrew Neil]

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@Rajesh3 wrote:

STM32F103C8 blue phil

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You mean Blue Pill ?

Note that a Blue Pill will (almost) certainly have a fake STM32 on it.

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@Rajesh3 wrote:

I'm a beginner in embedded systems.

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Save yourself a load of grief: get a genuine Nucleo board - which will include a genuine ST-Link.

eg, https://www.st.com/en/evaluation-tools/nucleo-f103rb.html

Cautionary tale on the perils of the Blue Pill (also, fake/clone ST-Links):

https://community.st.com/t5/stm32-mcus-products/blue-pill-stm32f1-board-gets-programmed-through-arduino-ide-but/m-p/667923

[TDK]

It is not possible to generate different frequencies on different channels of the same timer.

(If frequencies are 2x apart, and duty cycle is 50%, you can do this, but that's the only exception.)

[Tesla DeLorean]

One could perhaps use toggle mode, on a maximal counter, and then chase the CCx interrupts and CCRx points along that timeline.

Lot of balls to juggle, but could be considered.

One could perhaps use TIM+DMA+GPIO to drive a pattern buffer out some selective pins of a given bank via BSRR

[waclawek.jan]

> One could perhaps use toggle mode, on a maximal counter, and then chase the CCx interrupts and CCRx points along that timeline.

In this particular case - 10Hz and 100Hz - i.e. one of the frequencies is an integer multiple of the other and both are slow, so I'd run the 100Hz PWM "naturally", and the 10Hz by using "active on match/inactive on match" and changing CCRx in Update interrupt.

Probably not something that can be clicked in CubeMX; although I don't use Cube/CubeMX.

JW