3.4 KiB

This firmware is for the spark strober, using an STM32 F1 series micro-controller.



The spark strober switches mains electricity. This allows to switch on a flood light or stroboscope for a short time to create a light pulse.



  • blue pill, based on a STM32F103C8T6: development board to control everything
  • HLK-PM01 power module: 100-240V AC to 5V DC power supply to power the board and other peripherals (protected with a 0.25A glass fuse)
  • VS1838b: 38 kHz infrared demodulator to receive the codes from a remote control (connected using a 3.5 mm TRS jack)
  • G3MB-202P: compact 240V AC 2A solid state relay to switch mains electricity (protected with a 2A fuse)
  • infrared remote control sending NEC codes (low power version salvages from a multimedia player, high power version from Jedi iDual)


Hi-Link HLK-PM01:

  • AC: 100-240V AC mains
  • +Vo: 5V
  • -Vo: ground

Omron G3MB-202P:

  • 1: 100-240V AC mains line input
  • 2: 100-240V AC mains line output
  • 3: 5V with 330 Ohm resistor
  • 4: blue pill, PB6


  • 1, OUT: 3.5 mm TRS jack plug, ring
  • 2, GND: ground
  • 3, VCC: 5V (with 100 nF decoupling capacitor)

3.5 mm TRS jack socket:

  • tip: 5V
  • ring: blue pill, PB8, TIM4_CH3
  • sleeve: ground

blue pill:

  • PB8, TIM4_CH3: IR demodulator OUT
  • PB6: SSR control
  • 5V: 5V
  • GND: ground



Have a look at the application.c ir_action to changes the AC on/off switch animations and corresponding remote control code.


The source code uses the libopencm3 library. The projects is already a git submodules. It will be initialized when compiling the firmware. Alternatively you can run once: git submodule init and git submodule update.


To compile the firmware run rake.


To generate doxygen documentation run rake doc.


There are two firmware images: bootloader and application. The bootloader image allows to flash the application over USB using the DFU protocol. The bootloader is started first and immediately jumps to the application if it is valid and the DFU mode is not forced (i.e. by pressing the user button on the board or requesting a DFU detach in the application). The application image is the main application and is implemented in application.c. It is up to the application to advertise USB DFU support (i.e. as does the provided USB CDC ACM example).

The bootlaoder image will be flashed using SWD (Serial Wire Debug). For that you need an SWD adapter. The Makefile uses a Black Magic Probe (per default), or a ST-Link V2 along OpenOCD software. To flash the booltoader using SWD run rake flash_booloader.

Once the bootloader is flashed it is possible to flash the application over USB using the DFU protocol by running rake flash. To force the bootloader to start the DFU mode press the user button or short a pin, depending on the board. It is also possible to flash the application image using SWD by running rake flash_application.


SWD also allows to debug the code running on the micro-controller using GDB. To start the debugging session run rake debug.


The firmware offers serial communication over USART1 and USB (using the CDC ACM device class).