QUERY about MCLK clock drive on WM8898/ES8838 for Audio

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Joined: Fri Apr 24, 2020 1:45 pm

QUERY about MCLK clock drive on WM8898/ES8838 for Audio

Fri Apr 24, 2020 2:20 pm

Hi Vonger

We are a product design business in the UK. I have been familairising with VOCORE2 which we've bought from you, for a new project.
It's working beautifully - congratulations on a great product.

I have a question about Audio. Note, I have VoCore2, not Dock, so I don't have your sample: but I've looked at your Schematics.

I see you used WM8898 / ES8838 in the original Dock, and so I guess the drivers are in the current image.

My question is about the hardware design you used -- and the source of MCLK you used for the audio device (Master clock).

I think, if I am reading schematics right, you used GPIO0 originally to feed this ? I am guessing you were able to route a clock out of the CPU via GPIO to drive the ES8388 ?

But - on the later 'Dock20' Schematic, I see you drive MCLK, from a local crystal oscillator.

I am designing a project with audio now, using VoCore2, and I need to add WM8898 / ES8838 to my interface. I want to follow your best advice for the device -- would you recommend a local oscillator to drive MCLK, and if so, what frequency do you use ? I have seen both 384x fs and 256x fs as options.

(Could you also please explain, what the 'GPIO drive' to MCLK was).

I presume fs = 48Khz ? so a Crystal oscillator clock, needs to be either 12.288MHz or 18.432MHz I think. Can you confirm what you use on the Dock now ?

Many thanks for your help - much appreciated -- we hope to place a volume order with you soon.

With best regards
Mike H, London UK

Posts: 802
Joined: Sun Oct 19, 2014 6:00 am

Re: QUERY about MCLK clock drive on WM8898/ES8838 for Audio

Fri Apr 24, 2020 4:30 pm

GPIO0 is pinmux by refclk, which is 12MHz.(ES8388 USB mode)
It do not need crystal. Dock20? I do not remember this, but v2 dock from begin it do not need external oscillator.

Please check github.com/vonger/vocore2, we have a patch for es8388. And better to have a VoCore2 Ultimate, that will help you develop and save you a lot of time.

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