CC3220: cc3220 i2s master clock

Doug Mann

Part Number: CC3220

I’ve found myself a bit confused with the I2S (McASP) on the cc3220. I was hoping you might be able to offer some guidance.

I’m trying to interface a cc3220 to a ADS127L01 ADC in frame sync mode.

From the TRM it looks as if the I2S port can only act as Master. The problem I have is that the cc3220 can generate the frame and bit clocks to the adc, but I have no idea how I can source the synchronous MCLK (for sigma delta oversampling) that is needed for the ADS127L01? Usually, I expect a audio master clock out for a SOC with I2S master mode. I’m really confused that this does not show up in the TRM or pin muxing options. Is there a hidden mode or workaround for this issue?

Thanks,

over 8 years ago

0 Benjamin Moore over 8 years ago

TI__Mastermind 30800 points

Hi Doug,

The I2S on the CC3220 does not provide the MCLK as an output. This is a limitation of the peripheral.

Best Regards,
Ben M

0 Doug Mann over 8 years ago in reply to Benjamin Moore

Prodigy 50 points

Ben,

The absence of the audio MCLK, coupled with the lack of support for slave mode is an unfortunate oversight for the cc3220 i2s peripheral rendering it unusable by a vast majority of audio and signal processing applications.

Perhaps the next silicon "wish list" should consider adding one or both of these, as it it common knowledge that you need a synchronous MCLK, bit clock, and frame clock (unless you can synthesize MCLK from bitclock on the codec\adc\dac).

See TI's whitepaper on this topic:

www.ti.com/.../slaa469.pdf

0 Benjamin Moore over 8 years ago in reply to Doug Mann

TI__Mastermind 30800 points

Hi Doug,

Yes, our reference demonstrates use with a codec where the MCLK is synthesized from the bit clock using the TLV320AIC3254.

http://www.ti.com/tool/CC3200AUDBOOST

This boosterpack is also compatible with the CC3220.

Best Regards,
Ben M

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CC3220: cc3220 i2s master clock