USB dual CDC uarts for STM32F072CBT6

DMA-accelerated multi-UART USB CDC for STM32F072CBT6 microcontroller as Keil uVision5 project

Based on the example by majbthrd from https://github.com/majbthrd/stm32cdcuart

This code is ported and tested for the STM32F072CBT6 with two UASRTS: UART1 and UART3

Changes are in the GPIO and AFR registers. The source from the original project is imported into a Keil uVision 5 type project.

Enjoy!