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New ContributorCyclone V nRST assertion upon nPOR
Hello, I am looking for a confirmation on whether the nRST pin is driven low upon a nPOR input assertion. I have found no definite answer in the HPS TRM (cv_5v4 dated 2024.12.03).
But HPS TRM version 1.3 (Nov 2012), Table 3-3 page 3-7 says
with
I ran an experiment today on our prototype, asserting nPOR once the system has boot-up (linux) and see no assertion of nRST pin. Also, in the Reset Manager register description, I see no configuration bit that would enable/disable nRST assertion upon nPOR.
Can someone confirm the unconditional assertion of nRST upon a nPOR as I understand from HPS TRM from Nov 2012.
Thanks, Best regard
Pascal
Hi,
Apologies for the delay in getting back and thanks for cross-checking the older HPS TRM.
From newer TRM document, asserting nPOR does not drive the nRST pin low on Cyclone V. nPOR requests a cold reset while the Reset Manager drives nRST low (via rst_pin_rst_n) only during a warm reset.
Current Cyclone V HPS TRM (683126 21.2) lists rst_pin_rst_n under Warm Reset only, and an Altera KDB documents that the old handbook wording about cold/POR driving HPS_nRST was incorrect.
You can refer to the sections below (took the screenshot above from here)
https://docs.altera.com/r/docs/683126/21.2/cyclone-v-hard-processor-system-technical-reference-manual/module-reset-signals
https://docs.altera.com/r/docs/683126/21.2/cyclone-v-hard-processor-system-technical-reference-manual/reset-pinsThanks
Regards
Kian
2 Replies
PRega1Anyone with an answer ?
KianHinT_alteraFrequent Contributor
Hi,
Apologies for the delay in getting back and thanks for cross-checking the older HPS TRM.
From newer TRM document, asserting nPOR does not drive the nRST pin low on Cyclone V. nPOR requests a cold reset while the Reset Manager drives nRST low (via rst_pin_rst_n) only during a warm reset.
Current Cyclone V HPS TRM (683126 21.2) lists rst_pin_rst_n under Warm Reset only, and an Altera KDB documents that the old handbook wording about cold/POR driving HPS_nRST was incorrect.
You can refer to the sections below (took the screenshot above from here)
https://docs.altera.com/r/docs/683126/21.2/cyclone-v-hard-processor-system-technical-reference-manual/module-reset-signals
https://docs.altera.com/r/docs/683126/21.2/cyclone-v-hard-processor-system-technical-reference-manual/reset-pinsThanks
Regards
Kian
