STM32F4 DISCOVERY Board has noisy USART2 when board is powered by external source and USB ST-Link is disconnected.
I have an STM32F4 Discovery board with a USB->Serial converter connected to pins PA2 (TX) and PA3 (RX). I used CubeMX to configure usart2. My test code successfully sends data over usart2 when I power the discovery board as usual over USB.However whe...