output UART_TXD ); That’s not enough, though. You need to set the constraints to match the physical pins. The documentation is a bit of a mess in this regard because the serial port is on port B ...

It’s a protocol that has its niche, and there are a few interesting application notes for implementing the 1-wire protocol with a UART. Application notes are best practices, but [rawe] has ...

UART loopback path The UART IP was buried deep within the chip core, under several layers of hierarchy. The signals on the core were multiplexed onto several different pins and went through an I/O ...