USB Fifo not empty

[Mark Greally]

Posted on February 06, 2018 at 10:10

Hi.

I am doing a basic USB device using STM32F407 and the usb Rx and Tx Fifo's look strange. For example data in at address 0x50001000: 00CC0080 01000680 00400000 00C80000. Then is followed by the following at

address 

0x50001010: 002C0080 00

2

C0080 00

2

C0080 00

2

C0080

                  :                     :                  :                  :               :

               etc

When USB_FlushTxFifo and USB_FlushRxFifo are used the memory reads as '00CC0080............00CC0080' fpr all that section of the memory, when it should be empty. It should be empty. Why is there data in the fifo when it should be empty?

Thanks.

#stm32