2019-10-04 09:23 AM
Hi,
I would like to know if I can use STM32F446 and generate 192k I2s output. consider I need to use USB_OTG_HS.
I am trying to setup pins and clock configuration in STMCube, but for the I2S_APB1 it gives me range of 172MHZ to 192. and even with 192 in the configuration for I2S2(Master) it says the error between selected and real value is 2.8% how can I get 0%
Thanks
Neda
2019-10-09 11:53 AM
Hi,
I am assuming the above are different option on settings.
I did #4 and it works, but we may not want go with LQFP100 chip.
regarding #2 are you saying it is not a good idea to use a DAC or ADC with external PLL?
here is the settings I got by disabling I2S output as master.and we will use a ADC or codec with PLL on it. what do you think?
2019-10-09 01:46 PM
As in my previous example, for PLLI2S better set M=10, because then with N=147/160 you can get perfect both 44,1/48 kHz based sample rates. And use MCO2 divider to get lower master clock frequency, if required.
I'm just saying that you need to get master clock somehow. Without using SAI peripheral and I2Sx_MCK pin, the next reasonable options are MCO2 output or codec with integrated PLL (for example AK4558). With the former you have to check your codec's master clock phase requirements. With the latter you don't have to worry about master clock phase and you don't need to generate master clock on MCU at all.