pico-fpc/
????????? src/
???   ????????? boot/               # Boot/startup assembly sources
???   ???   ????????? boot2.S         # RP2040 boot2 (XIP flash init)
???   ???   ????????? crt0.S          # Flash-mode reset/vector startup
???   ???   ????????? crt0_ram.S      # RAM-mode minimal startup
???   ????????? hardware/           # Hardware abstraction units
???   ???   ????????? clocks.pas
???   ???   ????????? gpio.pas
???   ???   ????????? pwm.pas
???   ???   ????????? resets.pas
???   ???   ????????? rp2040.pas
???   ???   ????????? spi.pas
???   ???   ????????? timer.pas
???   ???   ????????? uart.pas
???   ????????? pico/               # Pico SDK abstraction layer
???   ???   ????????? pico.pas        # Main SDK unit (timing, init)
???   ???   ????????? pico_types.pas  # Common types
???   ???   ????????? platform.pas    # Platform helpers
???   ????????? rtl/                # Custom RTL overrides (experimental)
???   ???   ????????? system.pas
???   ????????? startup/
???   ???   ????????? startup.pas
???   ????????? wifi/               # CYW43 / Pico W work-in-progress
???   ???   ????????? cyw43.pas
???   ???   ????????? cyw43_ll.pas
???   ???   ????????? cyw43_spi_test.pas
???   ???   ????????? cyw43_stub.c
???   ????????? fpc_stubs.c         # FPC runtime stubs
???   ????????? startup_rp2040.S    # Legacy startup source
???   ????????? wifi_blink.pas      # Pico W blink example entry
????????? examples/               # Example programs
???   ????????? blink/
???   ???   ????????? blink.pas       # LED blink with pico unit
???   ????????? pwm/
???   ???   ????????? pwm_test.pas    # LED brightness sweep via PWM
???   ????????? spi/
???   ???   ????????? spi_test.pas    # SPI0 MOSI/MISO loopback test
???   ????????? uart/
???       ????????? uart_test.pas   # UART heartbeat transmit
???       ????????? uart_echo.pas   # UART echo server
????????? build/                  # Build output (UF2, ELF, etc.)
????????? build-wifi/             # pico-sdk/cmake WiFi build artifacts
????????? linker/                 # Linker scripts
???   ????????? rp2040.ld
????????? lib/                    # Compiled libraries
???   ????????? libcyw43_stub.a
???   ????????? libpico_wifi.a
???   ????????? libpicow_led.a
????????? scripts/                # Build helper scripts
???   ????????? build-wifi-lib.sh
????????? rp2040.ld               # Generic RP2040 linker script
????????? rp2040_flash.ld         # Flash/XIP linker script
????????? rp2040_memory.ld        # RAM build MEMORY definition
????????? rp2040_ram.ld           # RAM linker script
????????? Makefile                # Build system

make help              # Show available targets
make blink             # Build blink example (RAM)
make blink_flash       # Build blink example (FLASH)
make pwm_test_flash    # Build PWM example (FLASH)
make spi_test_flash    # Build SPI loopback example (FLASH)
make uart_echo_flash   # Build UART echo example (FLASH)