Now, I am able bring-up the caravel test. Observation with 6 time caravel test 1. 4 Time I Got == LOW chain PASSED. Valid IO = 0 thur 18. == == HIGH chain FAILED. Valid IO = 34 thur 37. == 2. 2 Time I Got =================================================================== == LOW chain FAILED. Valid IO = 0 thur 10. == == HIGH chain FAILED. Valid IO = 34 thur 37. == =================================================================== I was expecting same signature for all the test, look like there are different hold variation across run?

neat! was the powered hub + cable change what also allowed you to get past the infamous Winbond SRAM error, or did you have to change something else?

I am really not understood why was not working previously, I tried multiple thing, • Replaced Winbond Flash memory • Used Different USB cable • Tried in three Desktop - 2 Windows & 1 Ubuntu • External Power Feed 10V at Vin All cases had same Winbond Flash memory failure. When I switch back to USB power system, I see system working suddenly without failure - in all below combination • In Different USB Cable • All three Desktop - 2 Windows & 1 Ubuntu I can only suspect on • Connectivity issue at Nucleo Power selection Jumper J3 • Connectivity issue between nucleo and caravel HAT. I see only one Power Pin given between nucleo board and caraval HAT board, Where as Ground has 15 Pin connection.

I would expect the same results for a single chip, but different results for different chips.

I see at least two different signature for same chip.

yes I saw that

I'm reading this and it appears that you don't really know what fixed it?