Hi @matt-crc
Hope you are doing well and thanks for reading the article! So, here are my comments:
1- it says you need to use PF4 to kick the processor in overdrive. Does PF4 need to be used (ie special function) or can any GPIO be used? (ie is PF4 just used on the STM32N657-DK board)?
Any GPIO could be used on a custom hardware, but on the DK board the PF4 is the one connected to the feedback on the regulator that allows the voltage change. Please refer to the schematic> https://www.st.com/resource/en/schematic_pack/mb1939-n6570-c02-schematic.pdf , page 5:
2- Since ST published this article, are there any benchmarks or data (ie bus speeds) that were recorded when the core voltage was increased from 0.8V to 0.89V. It would be nice to know if we should implement this mod, or its really not worth it. What about reliability over time?
The need for the change is really application dependent, but it is reliable over time. The bus speeds and clocks are mentioned in the reference manual, but in summary:
- CPU M55 goes from up to 600MHz to 800MHz
- STNOC AXI is kept at 400MHz
- Neural ART (NPU) goes from 800MHz to 1GHz
- NIC AXI goes from 800MHz to 900MHz
3- I purchased the STM32N657-DK development board. Is the source code available for the demo on the board, and if so, where can I download it. It says by default the DK is not in overdrive mode, so I would like to modify the code to enable the overdrive.
We have several demos available outside the HAL driver ones that can leverage the use of the overdrive, please check this link to download them individually: STM32N6-AI | Software - STMicroelectronics, but the one that comes with the board is only provided in its binary format, due to licenses.
Hope this helps
