I have been trying to get the AD7768-4 to work with an L431.
I (belately) realized that the maximum SAI slave clock speed in the L4 is 25MHz. It appears that the APB1 clock speed is the limiting factor. I could potentially achieve 192ksps by replacing the ADC crystal with a 24.576MHz, but I really need a Nyquist of 100KHz minimum, so 256ksps is a must.
Looking at the data sheet of the F423, I'm not sure I understand it completely:
Is "Fs" supposed to be the incoming sampling frequency? So 256ksps * 128 = 32.768MHz in slave mode? And is this PER 32-bit slot? So only 64ksps per channel? Very confused.
TIA.
Here is the relevant page for the F446:
If the intent behind the SAI interface was to limit it to 192ksps, they should simply state that in the description. It would save a lot of people a lot of grief.
Finally, here is the G431:
Here, it *clearly* states that the maximum slave clock speed is 50MHz. Is this because the max APB1 clock frequency is 170MHz vs 50 and 45MHz in the F4?
