topic Output a kHz range clock through a GPIO? in Kinetis Microcontrollers

Output a kHz range clock through a GPIO?

nxa09603 — Fri, 03 Jul 2020 22:03:39 GMT

I'm trying to output a 4 kHz 50% duty cycle square waveform through a GPIO. What is the simplest way of doing that?

It doesn't need to be exactly 4 kHz. I accept some tolerance around the target.

I was considering to use FAST_IRCLK as time base, divide the clock by 1024 and output it. Is it possible?

I'm using MCUXpresso with KL02 SDK.

Thank you

Andre VB

Re: Output a kHz range clock through a GPIO?

myke_predko — Sat, 04 Jul 2020 16:40:54 GMT

Hey nxa09603‌,

The simplest way of doing it is to use one of the TPMs (Timer/PWM Modules) built into the KL02 to generate a PWM signal. Just taking a quick look at the datasheet/RM, you will use one of the TM#_CH# pins as your output.

I should note that the TPMs are different from the FTMs of other Kinetis parts but there should be an example in the SDK that you can see in MCUXpresso and copy over quickly.

Good luck,

myke

Re: Output a kHz range clock through a GPIO?

mjbcswitzerland — Sun, 05 Jul 2020 22:20:23 GMT

Available as open source on Git Hub "uTasker" including KL02 support and simulation - eg. generating 1kHz 20% output on PTB10:

Regards

Mark
[uTasker project developer for Kinetis and i.MX RT]