Any 32-bit Arduino core with ~64 KB of free RAM: ESP32 (all variants), RP2040 / RP2350 (Earle Philhower's Arduino-Pico or Mbed), SAMD51, nRF52840, STM32duino, Teensy, Renesas (UNO R4 is tight), Portenta. AVR boards are too small.

CI packages the library with tools/make_arduino.py and compiles every example for ESP32, ESP32-S3, ESP32-C3, Raspberry Pi Pico, Pico 2 and the Nano 33 BLE (nRF52840, Mbed).

python3 tools/make_arduino.py      # → dist/arduino/MicroCS-1.14.0.zip

Arduino IDE: Sketch → Include Library → Add .ZIP Library…. PlatformIO: lib_deps = https://github.com/amir1387aht/MicroCS with framework = arduino.

The Arduino IDE cannot pass -D options to a library, so the package carries its configuration in src/mcs_user_config.h (a copy of config/mcs_user_config.h: every option set to its default value; with --profile NAME, to that profile's values, written by tools/gen_config.py). Edit it in the installed library (Arduino/libraries/MicroCS/src/), or bake your own settings into the package:

python3 tools/make_arduino.py --config my_mcs_user_config.h   # your header instead of the template
python3 tools/make_arduino.py --profile lowram --define MCS_ENABLE_LINQ=0 --no-ws2812

Bluetooth LE: python3 tools/make_arduino.py --ble adds C# Ble, BleService and BleUart on the ArduinoBLE library (Nano 33 BLE / IoT, Nano RP2040 Connect, UNO R4 WiFi …; the package then depends on ArduinoBLE). Advertising, scanning and the GATT server work; the GATT client (Ble.Connect) and pairing do not — BLE.md.

--profile, --define, --no-ws2812, --no-servo, --ble and --fs (littlefs, yaffs2, or the built-in tinyfs) are written at the top of that file. Port options such as MCS_ARDUINO_NO_WIRE go there too. PlatformIO projects use the project's include/mcs_user_config.h or build_flags = -D… instead (CONFIGURATION.md).

• MicroCS_REPL — the board becomes a complete MicroCS device: C# REPL on Serial, files on LittleFS (ESP32 / RP2040), /boot.cs, /jobs.cfg and /main.cs at start-up, and the protocol MicroCS Studio and tools/mcs_remote.py use. ESP32: choose a Partition Scheme with SPIFFS/LittleFS (the default has one). RP2040: choose a Flash Size with an FS part (e.g. "2MB (Sketch: 1MB, FS: 1MB)"), otherwise files are kept in RAM.
• MicroCS_SD — the same with the files on an SD card (any core with the SD library).
• MicroCS_Embed — your sketch keeps loop() and runs C# from it.

mcs_arduino_cfg_t cfg = MCS_ARDUINO_CFG_DEFAULT;      // UART 0 = Serial, I2C 0 = Wire, SPI 0 = SPI
cfg.uart[1] = MCS_ARDUINO_UART(Serial1);               // any HardwareSerial / Stream class
cfg.i2c[1] = &Wire1;
mcs_arduino_hal_init(&hal, &cfg);
mcs_arduino_can_pins(5, 4);                            // ESP32: CAN.Open(0, 500000) (TWAI + transceiver)
mcs_arduino_i2s_pins(0, 26, 25, 22, 35);               // I2S.Open(0, ...): bclk, ws, dout, din

#include <LittleFS.h>
LittleFS.begin(true);                                       // ESP32: format on first use
static mcs_arduino_fs_t files = MCS_ARDUINO_FS(LittleFS, "littlefs");
cfg.fs_ops = &mcs_arduino_fs_ops; cfg.fs_ctx = &files;      // mcs_runtime_cfg_t

MCS_ARDUINO_FS(obj, format) takes any fs::FS of the ESP32 and RP2040 cores — LittleFS, SPIFFS, FFat, SD, SD_MMC, SDFS. On other cores include <SD.h> in the sketch and use MCS_ARDUINO_SD_FS(SD) after SD.begin(cs) (the SD library cannot rename, so File.Move / mv copy the file and delete the original; directories cannot be moved there).