0.9.0 — Pinout

Version 1.0.0 arrives when the pinout has survived 1000 hours of community torture. The changes from 0.9.0 to 1.0.0 are usually minor: renaming a few nets, clarifying current limits, marking two pins as "Do Not Use." But the psychological shift is immense. 1.0.0 means the board is ready for mass production. It means a KiCad symbol library can be locked. It means a company can order 10,000 units without fear.

For the seasoned engineer, a 0.9.0 pinout triggers a familiar mix of caution and excitement. For the beginner, it is a rite of passage: the first time they realize that pins have personalities, that 3.3V is not 5V, and that a footnote about "pull-down resistors" can save a weekend. Pinout 0.9.0

This is not elegant. It is engineering debt. But it is documented. And that documentation is the entire value of Pinout 0.9.0. What happens after Pinout 0.9.0? The community builds. Forums fill with questions: "My I2C device works on pin 22 but not pin 23—why?" The maintainers update a known issues list. Perhaps they discover that a certain analog pin has 100mV more noise than specified. That flaw becomes an errata. Version 1