https://john-galik-blog.pages.dev/ Field notes and project breakdowns en https://john-galik-blog.pages.dev/posts/2026-06-28-pn5180-bare-spi/ https://john-galik-blog.pages.dev/posts/2026-06-28-pn5180-bare-spi/ Sun, 28 Jun 2026 00:00:00 GMT The Arduino library hides a busy-wait handshake behind every send. Here is what the datasheet actually requires, and what the library invented.