Clock configuration for STM32L4R9 with USB-FS - SDMMC

[lukin]

Hi,

I would ask the community a suggestion for clock configuration.

I should use the USB ans Mass Storage Class using the SD card by SDMMC interface as memory. This function is used for 5 to 10% of my device usage, so I would decrease the SYSCLK for power consumption. Now it is set at 48 MHz.

Which could the right clock configuration to save power? I tried to simply set SYSCLK at 24 MHz but Storage is not recognized any more from Windows. Should I keep SYSCLK at 48 MHz as USB?

 

[lukin]

@Community member​ I tried this setting:

• SDMMC Clock: 48 Mhz, Clock Divider 8
• USB clock: 48 MHz
• SYSCLK: 24 Mhz

Using the USB MSC the device is not recognize, while if I use SYSCLK = 48 MHz it is correctly recognized. Which could be a correct clock configuration in order to get a lower clock for power consumption?

Thank you