Kinetis MicrocontrollersのトピックRe: Does the Kinetis KL26 MCU support 'USB clock recovery' when using the IRC?

Does the Kinetis KL26 MCU support 'USB clock recovery' when using the IRC?

2743294708 — Wed, 21 Nov 2018 02:14:23 GMT

I want to know, does the KL26 MCU support 'USB clock recovery' when using the IRC? I havn't find the information in 'KL26P121M48SF4RM'.

If supported, please give me the corresponding documents or example code projects that would accelerate the development.

Thanks.

Re: Does the Kinetis KL26 MCU support 'USB clock recovery' when using the IRC?

mjbcswitzerland — Wed, 21 Nov 2018 17:20:00 GMT

The KL26 doesn't have IRC48M and so doesn't support crystal-less USB device.

The KL27 is needed instead.

Regards

Mark

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Re: Does the Kinetis KL26 MCU support 'USB clock recovery' when using the IRC?

2743294708 — Thu, 22 Nov 2018 01:46:26 GMT

Dear Mark,

Thanks for your reply.

I have another question about this.

In the spec of KL26 chapter 3.8.1, there is a note says " The MCGFLLCLK does not meet the USB jitter
specifications for certification. ". Is there a method to ensure the MCGFLLCLK meets the USB jitter spec for certification when using the IRC?

Re: Does the Kinetis KL26 MCU support 'USB clock recovery' when using the IRC?

mjbcswitzerland — Thu, 22 Nov 2018 10:12:20 GMT

The only way to ensure reliable USB operation and fulfill certification requirements is to use a crystal/oscillator source for the external clock or on the dedicated USB clock input.

It is impossible with MCGFFLCLK.

Regards

Mark

Re: Does the Kinetis KL26 MCU support 'USB clock recovery' when using the IRC?

2743294708 — Sat, 24 Nov 2018 12:18:27 GMT

OK.

It's clear about the question. Thanks.