2024-08-21 03:02 AM - edited 2024-08-21 06:15 AM
Hi all, I have already searched on the forms and in general did not find an answer to my problem, I will be very grateful to you for help.
I need to create an output signal with a frequency of 100 Mhz as CLK in STM32H745. I used the Discovery Boards (STM32H745I-DISCO STM32H750B-DK) for the test.
1. I used timers with PWM and adjusted the ABM timer clock for 220 MHz, set up pre-scaler and counter period
But I achieve only 50 Mhz a clock as a maximum, with settings for 100 Mhz there is nothing at the output for CLK. To detect the clock I use PicOscope6404D (Bandwidth 500 Mhz).
2. I used as output ch A8 and adjusted A8 for RCC_MCO_1
I used the next settings but received the same result as for Timers not more than 50 MHz. Can you explain why I have this limitation (because the device settings show me that I can reach 100 Mhz but in real not )?
3. Finally I used the PA8 HRTIM_CHB2 timer and received high and very unstable frequency with very low amplitude. Do you how I can make a stable frequency and increase amplitude from HRTIM_CHB2?
2024-08-23 07:15 AM - edited 2024-08-23 07:16 AM
What does "PWM without a timer" mean? no.
The PWM signal, AFAIK, is sent out through the same output driver, and is affected by the same GPIO speed register setting.
I don't know where you get this 20Mhz figure, your OP said you were able to go as high as 50Mhz. Did you set the GPIO speed registers to a higher speed and retest?
SoftLit's screenshot shows MCO output is ~3.3 Vpp. Are you sure your measurement equipment is set up properly?
2024-09-04 03:46 AM
So after I suggested here that he needs to set the GPIO output to a higher strength, and after MasterT also suggested the same, OP started a duplicate thread - in which @TDK suggested that he needs to set the GPIO to a higher strength. Which fixed the problem.
I hate the internet. :raising_hands:
2024-09-04 06:22 AM
Yes, frustrating. FWIW, same thing happens to me all the time. Answer the question in the very first response, and OP doesn't read it, or ignores it, or something. Sorry about that.
A screenshot showing how/where to adjust the setting can sometimes improve your chances here.
2024-09-04 06:24 AM
Hello, actually it is works now, sorry I missed your responses
2024-09-04 06:25 AM
Thank you for your advice! I misunderstood your message
2024-09-04 12:44 PM - edited 2024-09-04 02:35 PM
@TDK, certainly nothing for you to feel sorry about.
Actually, I've probably done the same in the past - It's not malice. But yes quite frustrating for those trying to help. Just venting.
It's also been my experience that when posters get several suggestions, they tend to pick a few (usually the easiest ones) and ignore the others. Then the thread just keeps going as if those suggestions were tested but didn't work.
2024-09-04 02:18 PM
thank you so much, I really appreciate for your support, in the future I will be more attentive to people who helped me