Sure. You can do that. Its a better approach unless you need IrDA.

The advantage standards have is that they've generally thought through all the problems you'll otherwise have to discover by trial and error. You can also use other devices operating to that standard.

The disadvantage of standards is primarily that they are written by committees in a language spoken only on the outer planets of Beta Tauri (El Nath).

80% of the workload is in figuring out what the IrDA standards mean and then figuring out how you'll implement it.

I'm the only person I know crazy enough to attempt to implement IrDA in an 8051, I'm just in no hurry to do it. :-)

-Jay C. Box