Technical Reference I2S Clock config section is confusing

WiFive
Posts: 1160
Joined: Tue Dec 01, 2015 7:35 am

Re: Technical Reference I2S Clock config section is confusing

Postby WiFive » Sat Jul 22, 2017 7:44 pm

Yes, but none of those start with FUNC, the register layout is different, and you are passing a shift where a value is expected.

RoyceP
Posts: 5
Joined: Thu Sep 01, 2016 3:46 pm

Re: Technical Reference I2S Clock config section is confusing

Postby RoyceP » Sat Jul 29, 2017 4:00 pm

It would appear that you were correct.

Code: Select all

PIN_FUNC_SELECT(PIN_CTRL, CLK_OUT1_S);
PIN_FUNC_SELECT(PERIPHS_IO_MUX_GPIO0_U, FUNC_GPIO0_CLK_OUT1);

netted me a 40Mhz clock on GPIO0. The DAC was not working with that clock. The documentation for the DAC indicated that the clock for 256x 44.1kHz ought to be 11.2896Mhz.

I replaced the above with:

Code: Select all

REG_WRITE(PIN_CTRL, 0b111111110000);
PIN_FUNC_SELECT(PERIPHS_IO_MUX_GPIO0_U, FUNC_GPIO0_CLK_OUT1);

and got the desired frequency. The DAC began outputting analog data, seemingly happy with the corrected master clock speed.

I agree that the documentation should be updated to reflect the full bit string required in each configuration.

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