Hi all,
i am using the TWR_K60F Board with CPU: MK60FN1M0VLQ12.
I am trying to create a PWM Signal on a PIN (PTC3). The PWM Signal have to be a rectangle signal.
I used the FTM_Init Component from Processor Expert.
My configurations are:
Clock
-Clock gate --> enabled
-Clock source --> System Clock
- Prescaler --> divide by 1
- Counter Init --> 0
- Modulo counter --> 4
Channel
- Channel 2 --> Enabled
- Channel Mode --> edge-aligned PWM
- channel value register --> 2
- Pin --> Enabled (PTC3)
Now i have a PWM signal with a period of 0.104 us (9.6 MHz) and a duty cycle of 50%.
If i look at the oscillocop then i see the following signal
But it has to be a rectangle signal. If i reduce my frequence (for example to 1MHz) then i will get a rectangle signal like that:
That is what i need because my camera needs a PWM signal that have a rising time maximum of 5 ns.
I also tried to add a GPIO_Init Component. I enabled the PTC3 - pin (pin sharing) and for the drive strength i selected high.
But i did not help. So if the frequence is to high then i will get a sinus wave.
What can i do?
I need a PWM signal with a frequence of 24 MHz and a duty cycle of 50%. With my configuration i will not get a rectangle signal but almost a sinus wave.
Thank you for your help!
Best Regards
Armend Gecaj
已解决! 转到解答。
Hi Armend,
I am afraid that may caused by your 50MHz bandwidth oscilloscope.
See the 5989-5733EN (Evaluating Oscilloscope Bandwidths for Your Application).
Best Regards,
Robin
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The extreme 'overshoot' even on the slow-speed-waveform's edges tells me you are also dealing with a 'long wire' and 'improper termination' for the edge-rates you are trying to support. Try putting a 47ohm resistor in series right at the Kinetis output.
I also assume the shown 'vertical scale' of 20V/div is 'expecting' a x10 probe, while you have a low-bandwidth x1 probe attached (straight wire???).
Hi EARL GOODRICH
you are right. It has to be a x10 probe, not a x1 probe.
I will also try to put a 47 ohm resistor in series right at my output.
Thank you for your help.
Best Regards
Armend
Hi Armend,
I am afraid that may caused by your 50MHz bandwidth oscilloscope.
See the 5989-5733EN (Evaluating Oscilloscope Bandwidths for Your Application).
Best Regards,
Robin
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Note: If this post answers your question, please click the Correct Answer button. Thank you!
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