NeoPill
a Blue Pill Neopixel Emulator, firmware for STM32F103C8T6.
To build with STM32CubeMX (6.1.1), open bluepill_neoemu_clk.ioc, generate code in a selected folder. Locate and copy over the 3 files main.c, usbd_cdc_if.c, usbd_cdc_if.h . Build with selected environment (originally used Keil uVision 5.26.) Flash into a Blue Pill. Follow instructions at https://hackaday.io/project/179916-neopill
Or use STM32CubeProgrammer v2.6.0 to flash the Hex file.
Python code for the PC side is 'stripsym.py', and two YAML config files ledstrip.yaml, ledmatrix.yaml.
Command Line: python stripsim.py ledstrip.yaml or python stripsim.py ledmatrix.yaml