STM8S105K4 Development Board: Pinout and First Project Setup

By Official Hobby Components Online Store | Buy Electronic Kits, Components, Boards, Shields, Modules | Published: 2026-11-02

Category: How-to Guides

Get your STM8S105K4 development board wired, programmed, and blinking an LED. This step-by-step guide covers pinout, STM8 programming setup, and a first project.

Quick answer

To get started with the STM8S105K4 development board, wire it to a programmer, set up the STM8 toolchain, and flash a simple LED blink program. The board breaks out most I/O pins on standard 2.54mm headers, so you can prototype without soldering.

What the board gives you and what it doesn't

The STM8S105K4 development board is a breakout for the STM8S105K4 microcontroller, an ultra-low-cost option for embedded control. It provides access to most I/O pins via 2.54mm pitch headers, which means you can connect sensors, LEDs, and other peripherals using standard jumper wires. However, the board does not include an on-board programmer or debugging interface, so you will need an external ST-Link or compatible tool. Also, the catalog does not list specific pin functions or voltage regulators, so always consult the STM8S105K4 datasheet for exact pin assignments and electrical limits.

Choosing a programmer and toolchain

You can use ST-Link/V2 or a compatible SWIM programmer to flash the STM8S105K4. For software, ST's free STVD IDE with the Cosmic STM8 compiler is a common choice, but SDCC (Small Device C Compiler) also supports STM8 and is open-source. The board itself does not dictate a toolchain, so pick one based on your comfort with IDEs and licensing. Keep in mind that the STM8S105K4 has limited flash and RAM, so avoid bloated libraries.

Step-by-step setup for your first STM8S105K4 project

Connect the programmer: Wire the SWIM pin, ground, and reset from your ST-Link to the corresponding pins on the board's header. Double-check the pinout against the STM8S105K4 datasheet before powering up. A common mistake is swapping SWIM and reset; verify with a multimeter in continuity mode.
Install the toolchain: Download and install STVD with the Cosmic compiler, or set up SDCC for STM8. Create a new project and select the STM8S105K4 device. If using SDCC, ensure the device header file is included; missing headers cause compile errors.
Write a blink program: Configure one GPIO pin connected to an LED (or an external LED via a resistor) as output. Toggle it in a loop with a delay. Use the datasheet to find the correct register names and bit positions. Forgetting to set the pin as output is a common mistake; the LED will stay dark.
Compile and flash: Build the project and download the .hex or .elf file using your programmer's software. Power the board from a stable 5V or 3.3V supply as required by your setup. If flashing fails, check that the programmer is selected correctly and the board is powered.
Verify and iterate: Once the LED blinks, you have a working baseline. Modify the delay or add a button input to confirm I/O works. Always keep a current-limiting resistor in series with LEDs. Skipping the resistor can damage the microcontroller pin; use 220Ω–1kΩ for standard LEDs.

Product facts

STM8S105K4 Development Board: Based on the STM8S105K4 microcontroller, an ultra-low-cost solution for embedded control. This makes the board ideal for budget-conscious projects where basic control and I/O are needed.
STM8S105K4 Development Board