Have you tried to develop a key input feature on your small embedded platform with a serial input?
It is not so easy to implement correctly because the input methodology is using a complicated protocol known as VT100.
In my recent project "Natural Tiny Shell (NT-Shell)" provides VT100 compatible terminal control features for small embedded systems.
However, the middleware is still large for small embedded processors such as 8-bit MCUs, 16-bit MCUs and also for small 32-bit MCUs like Cortex-M0.
This "MicroShell" middleware provides a minimal terminal control for the platforms.