# pcb-rnd devlog

## requirements for parametric footprint generation

by Igor2

It's appealing to write parametric footprint generators for new footprint families: invest some time once, and have a tool that can spit out dozens of footprints. However, it is not always worth having a generator instead of static footprints. The minimal requirements for a generator are:

- the footprint family is a series of footprints that can be generated using the same code, with changing some base properties (e.g. number of pins)
- dimensions and other properties can be calculated from the base properties with reasonable formulas and conditional code; e.g. sot* is not a good candidate for generation, as sot23 or sot89 can not be generated from some common ancestor by varying one or two parameters, but would need a large table that translates package name to a pattern - easier to keep those in static footprint files
- has a reasonable amount of existing variations; e.g. it is not worth writing a generator for the dsub family because there are only a few of them in common use (db9, db15, db25, and maybe db37).
- preferably a link to a datasheet that shows at least 3 members of the family; if that's not possible, separate datasheets describing at least 3 members of the family.