The AVR274 describes a Single-wire Software UART which is interrupt-based and looks pretty cool.
I did some research and found some references that seem to suggest that SoftwareSerial supports half-duplex single pin UART, but I see nothing on the documentation nor have been able to find any simple and lightweight implementation/example of a single pin half-duplex except for a project on GitHub called SoftwareSerialWithHalfDuplex. But this project seems abandoned and AFAICT is based on an older version of SoftwareSerial.
Maybe something from scratch based on the AVR274 and related notes(AVR304,AVR305,AVR307) would be more appropriate for a single pin UART?
Does anyone know if this has already been done and/or how to use SoftwareSerial for single pin half duplex??
Single pin half duplex without signal buffers? Or with buffers? You really are going to have to share your hardware details to get reasonable answers to this one. Because, half duplex without buffers would require some very special pin configuration tricks.
I did some research and found some references
which you didn't share with us... not the app note either. Some links would be appreciated.
AVR274 should support any AVR that has external interrupt and 8-bit timer compare interrupt.
This very detailed pull request seems to suggest that single pin half duplex worked on SoftwareSerial at some point, but the documentation doesn't mention that anywhere:
Thanks for that update. Probably, it is so seldom used, that nobody really cared about it enough to maintain the functionality in new releases. I think it also has other limitations that tend to overshadow that omission.