What must be the SCI clock frequency before setting SCI_CLOCKF Register in VS1053b?

Writing software that inputs and/or outputs audio and performs DSP algorithms such as filters, new codecs or audio effects.
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Arun Joe
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What must be the SCI clock frequency before setting SCI_CLOCKF Register in VS1053b?

Post by Arun Joe » Wed 2017-04-26 10:53

Hi,
I'm using VS1053b for encoding audio.
The input master clock to VS1053b is 12.288MHz and the Serial Clock form master(Controller) is 5 Mhz.
The SCI_CLOCKF is configured to 4.5x clock to get 55.296 MHz.
After configuring SCI_CLOCKF should I increase the Serial Clock?'
what about the clock rate before configuring SCI_CLOCKF?
It is said in the datasheet that, the maximum speed for SCI reads is CLKI/7.
So is it 12.288/7 before configuring SCI_CLOCKF to 4.5x?

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pasi
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Re: What must be the SCI clock frequency before setting SCI_CLOCKF Register in VS1053b?

Post by pasi » Wed 2017-04-26 11:07

After reset the vs1053b runs at 1.0x clock, i.e. CLKI equals XTALI. You should thus use at maximum 12.288MHz/7 = 1.7MHz SPI clock.

After you have written SCI_CLOCKF (and DREQ is high again), you can increase the SPI CLOCK, but you don't need to. 4.5x12.288MHz / 7 is 7.9MHz, so 5MHz SPI CLOCK would be ok.
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