diagramas: https://gbatemp.net/threads/internal-modchip-samd21-trinket-m0-gemma-m0-itsybitsy-m0-express-guide-files-support.508068/

programar: https://gbatemp.net/threads/modchip-software-simple-uf2-with-switchboot-save-fuses-without-autorcm.526607/

simple udf: https://gbatemp.net/threads/basic-modchip-dongle-uf2-sd-boot-files-trinket-rebug-rcmx86-others.518574/