Hello,

I'm a student in Electronic Engineering and I'm testing your USB 2.0 core. I have some question to ask!

When SIE enter in Reset State (usbf_utmi_ls) the signal xcv_set_hs = 1'b1 and 1.5ms later SIE enter in Speed_Neg so that  drive_k_d = 1'b1; then DataOut <= 8'hff (usbf_utmi_if) generating a Chirp K on the bus.

 

First question: doesn't Chirp K a trasmission of all 0s data? Why is    DataOut of all 1s data, in the source code?

 

Second question: UTMI Specification (Intel v 1.05) in HS Detection Handshake Timing Behavior (HS Mode), the signals XcvrSelect=0 and Chirp K are generated at same time (T1), instead in the core are generated in different instant! Could you explain why? Is it ok equally?

 

Thank you

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