Already finished and nicely working solder paste dispenser. Powered with cheap ebay mini DC motor with gearbox (100RPM) and long M3 shaft secured by two axial bearings also from ebay. Body of both control box and dispenser is fully 3D printed. Accepts standard ebay 3ml luer lock syringes. Firmware supports dispensing speed configuration and also retraction to prevent leaks. Push button is available on the control box as well as on the handheld unit to be able to control the dispensing according to personal preferences.
Microcontroller pin mapping (aka hardware-firmware interface) using STM32 CubeMX and complete firmware for AC6 system workbench. Includes display driver. Tested during real PCB assembly and works like a charm.
So the solder paste dispenser is finally ready for daily use and tested.
In normal mode: - middle button pulls (retracts) the paste with maximum speed while the button is pressed - right button pushes the paste (first with maximum speed for retract duration and after that with user defined speed), when released it immediately retracts (pulls) the paste for user defined time.
Other modes are just configuration of speed and retraction time.