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Author: ole

README.md

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+# Embedded Swift on the Raspberry Pi Pico
+
+A proof of concept for executing Embedded Swift code on the [Raspberry Pi Pico](https://www.raspberrypi.com/products/raspberry-pi-pico/). The main program is written in C (built with the official Pico C SDK) and calls into a statically linked Swift library.
+
+## Prerequisites and Installation
+
+### Hardware
+
+- A [Raspberry Pi Pico](https://www.raspberrypi.com/products/raspberry-pi-pico/)
+- Optional but recommended: a [Raspberry Pi Debug Probe](https://www.raspberrypi.com/products/debug-probe/) for more convenient flashing
+
+### Software
+
+- Host OS: macOS 13.x or 14.x
+
+- A recent nightly Swift toolchain from [swift.org](https://www.swift.org/download/). Tested with the December 7, 2023 toolchain.
+
+- A clone of the [Raspberry Pi Pico C/C++ SDK](https://github.com/raspberrypi/pico-sdk/):
+
+  ```sh
+  # This project expects to find pico-sdk in a sibling directory to itself.
+  cd ..
+  git clone https://github.com/raspberrypi/pico-sdk.git
+  cd pico-sdk/
+  git submodule update --init
+  cd ..
+  ```
+
+- [CMake](https://cmake.org/) and [Ninja](https://ninja-build.org/):
+
+  ```sh
+  brew install cmake ninja
+  ```
+
+## Configuration
+
+Open the file `CMakeLists.txt` in the root folder. Edit these two lines to match your setup:
+
+```cmake
+…
+    set(PICO_SDK_PATH "${CMAKE_CURRENT_LIST_DIR}/../pico-sdk")
+…
+    set(Swift_Toolchain "org.swift.59202312071a")
+…
+```
+
+## Building
+
+```sh
+cd pico-embedded-swift
+mkdir build
+cd build
+cmake -G Ninja ..
+ninja
+```
+
+This produces the executable `PicoLinksSwift.elf` in the `build` directory. You have two options to copy this to the Pico:
+
+1. Via the USB Mass Storage interface: use the provided `build/elf2uf2/elf2uf2` tool to convert the `.elf` file to `.uf2`.
+2. Via the debug probe. I use [probe.rs](https://probe.rs/) for this, which is a tool from the Rust community, but it works in this context too:
+
+    ```sh
+    probe-rs run --chip RP2040 PicoLinksSwift.elf
+    ```