Time taken to change USB state

Forum|Forum|1 year ago
March 18, 2024
3 replies
2494 views

I am running USB in Mass Storage host mode. On connecting the device, USB FLASH stick, it takes around 20 seconds to change the Appli_Sate from APPLICATION_START to APPLICATION_READY in usb_host.c file.

It is normal ? Can the time be reduced ?

Thanks

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Best answer by AScha.3

ok, so via swd + DWT counter ->

about 9,2 ms from inserted to fatfs mounted ok;

is 64 GB (noname chinese..) USB stick, exfat , 50GB free.

btw

How often you call the MX_USB_HOST_Process(); ?

I call it in main loop about every some 5us ....nothing else to do now, waiting for first command.

So this might be maximum speed, that can be achieved .

ed

+

Just for fun - had the idea, to try an old SanDisk 32GB stick, fat32, also, got ->

about 15ms insert to mounted. Ok for this piece of plastic shi.t , i think.

F

FBL

Technical Moderator

Hello @Nico3

Are you sure you are not printing to VCP/ UART or any terminal while debugging? It seems like an amount of time taken for printing debug information.

N

Nico3Author

Graduate II

Hi

Please note I am not printing anything. I also commented my remaning code and just checked the change in state on inserting the USB stick. It takes ~30 second to go from APPLICATION_START to APPLICATION_READY.

I checked both on STM32F4 discovery as well on board designed by me. It is coming same ~30 seconds.

The USB stick is 32 GB, SCANDISK & FAT formatted.

P

Pavel A.

Super User

Then the contrary, add some prints/traces to understand where it spends its time.

Do not set breakpoints because USB requires realtime reaction from the device.

Of course, 30 sec. delay is not normal.