# Structure - `FreeRTOS-Kernel` - FreeRTOS kernel source code - `FreeRTOS-glue` - Extra glue to hold together FreeRTOS kernel and flipper firmware - `app-scened-template` - C++ app library - `bit_lib` - library for working with bits/bytes directly - `callback-connector` - Callback connector library - `cmsis_core` - CMSIS Core package, contain cortex-m core headers - `cxxheaderparser` - C++ headers parser, used by SDK bundler - `digital_signal` - Digital signal library: used by NFC for software implemented protocols - `drivers` - Various flipper drivers - `fatfs` - FatFS file system driver - `flipper_application` - Flipper application library, used for FAPs - `flipper_format` - Flipper File Format library - `heatshrink` - Heatshrink compression library - `ibutton` - ibutton library, used by iButton application - `infrared` - Infrared library, used by Infrared application - `lfrfid` - LF-RFID library, used by LF RFID application - `libusb_stm32` - LibUSB for STM32 series MCU - `littlefs` - LittleFS file system driver, used by internal storage - `mbedtls` - MbedTLS cryptography library - `microtar` - MicroTAR library - `mlib` - M-Lib C containers library - `nanopb` - NanoPB library, protobuf implementation for MCU - `nfc` - NFC library, used by NFC application - `one_wire` - OneWire library, used by iButton application - `print` - Tiny printf implementation - `digital_signal` - Digital Signal library used by NFC for software implemented protocols - `pulse_reader` - Pulse Reader library used by NFC for software implemented protocols - `stm32wb_cmsis` - STM32WB series CMSIS headers, extends CMSIS Core - `stm32wb_copro` - STM32WB Copro library: contains WPAN and radio co-processor firmware - `stm32wb_hal` - STM32WB HAL library, extends STM32WB CMSIS and provides HAL - `subghz` - Subghz library, used by SubGhz application - `toolbox` - Toolbox library, contains various things that is used by Flipper firmware - `u8g2` - u8g2 graphics library, used by GUI subsystem - `update_util` - update utilities library, used by updater