STM32 HAL library for MAX7219.
http://msalamon.pl/nigdy-wiecej-multipleksowania-na-gpio!-max7219-w-akcji-cz-1/
The project uses STML476RG Nucleo board but it's easy to port to other MCU with HAL libraries.
This repository is for 7-segment digits display only. For 8x8 matrix driver go to: https://github.com/lamik/MAX7219_matrix_STM32_HAL