STM32f103 PWM output

yangfeng

STM32f103 PWM output [Copy link]

After looking at several examples, I still don't understand how to set the value of TIM_period when outputting PWM.
The reference book says: Since the clock frequency of the TIM1 counter is 72MHz, and the desired channel output frequency is 17.57KHz, the value of the TIM1 prescaler TIM1_period is 0xFFFF. How is this value calculated?
Please give me detailed instructions if you know. Thank you in advance!

feitian9215

                                 Which reference book?

updowncreay

STM32 processor development and application based on MDK
Beihang University
Edited by Li Ning

wode3000

Which page?

It is best to copy the relevant content in full, as no one can answer a question with just a few words.

stonepal

Page 283 of the book
Design requirements: Control the TIM1 timer so that each channel output is inserted into the complementary PWM output, and the output frequency of each channel is 17.57KHz. The duty cycle of channel 1 is 50%, the duty cycle of channel 2 is 25%, and the duty cycle of channel 3 is 12.5%.
Software design: Since the constant frequency of the TIM1 counter is 72MHz, it is hoped that the output frequency of each channel is 17.57KHz. According to the formula f=TIM1CLK/(TIM1_period+1), the value of the TIM1 prescaler TIM1_period is 0xFFFF
TIM1_prescaler=0x0
TIM1_period=0xFFFF
TIM1_ClockDivision=0x0
TIM1_RepetitionCounter=0x0

fengbingchun

                                 You can try that example. There may be a typographical error, where 0x0FFF is written as 0xFFFF.

智能abc

                                 I'll try it then, thanks to the moderator!!!

yang3509771

                                 The coefficient must be deduced from the formula

huangluling

                                 The publisher is too irresponsible

紫色宇宙

                                 It is best to read English materials, which have fewer errors. Translated Chinese materials will always have errors or inaccuracies.

star_jia

                                 Well, thank you for your pointers!

蓝天白云

                                 The output frequency is 17.57KHz. According to the formula f=TIM1CLK/(TIM1_period+1), the value of TIM1 prescaler TIM1_period is 0xFFFF