04-02-2021 05:03 AM
We have several product featuring the XC7Z020 chip, we are now investigating a problem where, sometimes, the FPGA fails to boot.
After looking at the power on sequence we found that this happens always when PS_SRST_B is held asserted during the power on sequence.
We have a button connected to this reset, and if we keep the button pressed at the power on, when the button is released the FPGA fails to boot.
All the documentation I found is on the PS_POR_B that can accidentally trigger a "Secure Lockdown", but i could not find any recommendation about PS_SRST_B.
Has anybody any clue about why this can be happening?
04-09-2021 07:41 PM
04-10-2021 05:29 AM
Thanks for your reply,
The post you linked is basically telling me that PS_SRST_B resets the system, and that's OK.
Let my clarify my situiation
I power on board with PS_SRST_B held LOW (asserted), and the zynq will not start booting, ans that's fine, this is what i expect too.
I deassert PS_SRST_B (HIGH) but the zynq does NOT start the boot process, and this is not the expected behavior.
04-16-2021 02:13 AM
04-16-2021 02:31 AM
I can do all the tests that I want, If i send a POR_B afterward it will trigger an hard reset and the ZYNQ will boot, as expected, if I sent a PS_SRST_B instead, nothing happens.
If course this is not a viable solution since this is a poweron sequence driven only by passive components.
I already looked at the documents, but I could not find anything about it, maybe I have overlooked something, if you can point me out at the right document/chapter i can double check the boot sequence.