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USB reports and CRC

Question asked by VDM on Nov 8, 2013
Latest reply on Nov 12, 2013 by VDM
Hello everyone,

I have a product based on an STM32 and a SPI flash NOR memory.
I store some data inside the flash NOR, then I read them back through USB.

Sometimes (very rare, but happens ..), I get a few corrupted bytes when I read them through USB.

The question is :
Is it possible that the data can be altered during USB transfer ?
I don't include a CRC or chekcsum within the data of my HID reports, should I ?
Or does the USB stack over my hid reports includes a CRC and an automatic "retry" if the checksum fails, meaning that the Windows function that reads the USB report is sure to get non-altered data ?

If USB HID reports are "error-free", I guess I should secure my write and read operations on the NOR memory.

Thanks for your help.
Best regards,