Arduino¶

OpenSiFli has a beta Arduino core for SF32 based on Zephyr: OpenSiFli/ArduinoCore-zephyr. It publishes the sifli:sf32lb52 Arduino package, appears in Boards Manager as SiFli Serial Boards, and currently targets the SiFli SF32LB52 DevKit LCD board.

This is a good path for sketches, quick peripheral checks, demos, and early prototypes. For production firmware, Bluetooth stack tuning, graphics-heavy applications, low-power optimization, or custom board bring-up, use SiFli-SDK.

Beta core

OpenSiFli marks this Arduino core as BETA and says to use it for testing only. Features, APIs, loader behavior, package contents, and release mechanics may change. Do not treat it as production-ready.

What You'll Need¶

Hardware

SiFli SF32LB52 DevKit LCD.
A USB Type-C data cable connected to the board's USB-to-UART path.
A computer running Windows, macOS, or Linux.

Software

Arduino IDE 2.x or Arduino CLI.
The OpenSiFli sifli:sf32lb52 Arduino package.
A serial monitor.

Install the Board Package¶

Open Arduino IDE > Settings and add this URL to Additional Boards Manager URLs:

https://github.com/OpenSiFli/ArduinoCore-zephyr/releases/latest/download/package_sifli_index.json

For users in mainland China, use the mirrored package index:

https://downloads.sifli.com/github_assets/OpenSiFli/ArduinoCore-zephyr/releases/latest/download/package_sifli_index_cn.json

Then open Boards Manager, search for SiFli Serial Boards, and install the sifli:sf32lb52 platform.

With Arduino CLI:

arduino-cli core install sifli:sf32lb52 \
  --additional-urls https://github.com/OpenSiFli/ArduinoCore-zephyr/releases/latest/download/package_sifli_index.json

For the China mirror:

arduino-cli core install sifli:sf32lb52 \
  --additional-urls https://downloads.sifli.com/github_assets/OpenSiFli/ArduinoCore-zephyr/releases/latest/download/package_sifli_index_cn.json

Select the Board¶

In Arduino IDE, select:

SiFli SF32LB52 DevKit LCD

The board FQBN is:

sifli:sf32lb52:sf32lb52devkitlcd

The OpenSiFli board definition maps this Arduino board to the Zephyr target sf32lb52_devkit_lcd and the variant sf32lb52_devkit_lcd_sf32lb525uc6.

Choose Build Options¶

The core exposes two important menus:

Build options

Menu	Option	Meaning
Mode	`Standard`	Sketch starts automatically after loading.
Mode	`Debug`	Zephyr shell waits for the `sketch` command.
Link mode	`Dynamic`	Sketch is packaged for the Zephyr loader.
Link mode	`Static`	Sketch is linked into a flashable binary.

Choose Dynamic for the Zephyr-loader workflow. Choose Static when you need the sketch linked into a flashable firmware image.

Put the Board in Serial Download Mode¶

OpenSiFli documents that first use requires the board to be in serial download mode. Use the boot/reset sequence for the SF32LB52 DevKit LCD, then upload from Arduino IDE or CLI.

The upload tool is sftool.

Upload a Serial Smoke Test¶

Start with serial output. It confirms upload, reset, runtime startup, and console routing without depending on LED polarity:

void setup() {
  Serial.begin(115200);
}

void loop() {
  Serial.println("Hello from SF32 Arduino");
  delay(1000);
}

Upload from Arduino IDE, or use Arduino CLI:

arduino-cli compile \
  --fqbn sifli:sf32lb52:sf32lb52devkitlcd:link_mode=dynamic \
  /path/to/YourSketch

arduino-cli upload \
  -p /dev/cu.usbserial-XXXX \
  --fqbn sifli:sf32lb52:sf32lb52devkitlcd:link_mode=dynamic \
  /path/to/YourSketch

Replace /dev/cu.usbserial-XXXX with your board's serial port. On Windows, use the matching COM port. On Linux, use the matching /dev/ttyUSB* or /dev/ttyACM* port.

Open the Serial Monitor at 115200 baud. In Standard build mode, the sketch should print one line per second. In Debug build mode, open the Zephyr shell and run:

sketch

Upload Blink¶

Check whether the installed SF32LB52 DevKit LCD variant defines LED_BUILTIN; do not assume that an Arduino pin number is universal. If the macro is available and the board's onboard LED is mapped by the variant, try Blink after the serial smoke test succeeds. Otherwise, confirm the LED connection and polarity from the board documentation before selecting a GPIO.

void setup() {
  pinMode(LED_BUILTIN, OUTPUT);
}

void loop() {
  digitalWrite(LED_BUILTIN, HIGH);
  delay(500);
  digitalWrite(LED_BUILTIN, LOW);
  delay(500);
}

Troubleshooting¶

Table: Troubleshooting

Symptom	Check
Package does not appear	Confirm the package index URL and use Arduino IDE 2.x.
Upload fails	Put the board in serial download mode and make sure no serial monitor is holding the port.
Sketch does not start	Confirm Mode. In `Debug`, run `sketch` from the Zephyr shell.
Undefined Zephyr symbol	The core README says missing Zephyr functions may need to be exported in `loader/llext_exports.c` and the loader rebuilt.
Zephyr subsystem missing	Enable the required `CONFIG_` option in the board `.conf`, rebuild the loader, and upload it.
Out of memory	Zephyr shell and dynamic sketch loading consume RAM; reduce stack usage or switch build mode where appropriate.

Current Scope¶

The current published package targets the SF32LB52 DevKit LCD and remains beta for testing. Before trying another board or relying on an API, check the upstream repository and the release notes for the exact package version; support in Zephyr or SiFli-SDK does not by itself establish support in this Arduino package.

Last updated: 2026-10-10