Crate pico_pll_config

A procedural macro for generating PLL configuration parameters.

The implementation is based on the Python script provided in the RP2040 SDK: $PICO_SDK/src/rp2_common/hardware_clocks/scripts/vcocalc.py

The macro takes a frequency (in kHz) as a literal and expands to an expression of type Option<PLLConfig>.

The algorithm searches over an expanded parameter space (REFDIV, FBDIV, PD1, and PD2) using hard-coded defaults (e.g. a 12 MHz input, minimum reference frequency 5 MHz, VCO limits between 750 and 1600 MHz) and selects the configuration with the smallest error relative to the requested output frequency (converted from kHz to MHz).

Macros

pll_config

The pll_config proc macro takes a frequency in kilohertz as a literal and expands to an expression of type Option<PLLConfig>.