Hello, everyone!
Dear yordan1, I am sorry. Yesterday, I may not have fully understood your problem, so I thought that just looking at the pin diagram could solve it directly. If you need 9 pins that can be directly referenced, I suggest these 9 pins GPIO(19, 20, 21, 26, 33, 34, 45, 47, 48). These 9 pins are the ones I have just experimented with and can continue to output. The purple part in the document pin diagram is the internally defined pins. If the connection is defined, it may cause the internally defined functions to be unusable. I hope these can be helpful to you.
Dear nmcc and bns, I often see you providing valuable opinions on many professional issues. Thank you for your continuous support and understanding. I believe that everyone browsing forums hopes to find useful advice for themselves.
Wishing everyone a happy life!