STM32H7 - "dedicated internal audio PLL"

[Smith.David]

Hi!

The datasheet suggests there is a "dedicated internal audio PLL" in the H7. Can you elaborate further on this PLL? I don't see it singled out anywhere. What are the performance specs?

Thanks!

[waclawek.jan]

I believe this is a marketing statement, taken over from previous models (such as the 'F4xx) where some of the PLLs were indeed committed to audio blocks.

In 'H7, there is more connectivity from the PLLs to various clocks, so that "dedication" is not that "stringent"; however, most of the other blocks usually don't need clocks separate from the kernel clock (maybe with exception of USB and ETH). There's also the dedicated I2S_CKIN clock input pin.

See Peripherals dedicated to audio applications subchapter of RCC chapter in RM0433.

JW

[Smith.David]

Thanks JW,

I wa expecting to find some technical detail hidden in a PDF about an internal ultra-low-noise fractional-N PLL specifically for aduio. I'll use the I2S_CKIN. Shame there is not a second I2S_CKIN.

[Smith.David]

Next question relates to multichannel i2s with 4 dat for the likes of 7.1 Are the SAI blocks single dat tx single dat rx?

[waclawek.jan]

> Are the SAI blocks single dat tx single dat rx?

SAI supports up to 16 slots per frame, see the SAI chapter in RM.

JW