The EN is used for the read or write bus cycle. If you look at the bus timing specs for the display, you need to set your RS, RW and DATA(if you're writing) ,have these stable for about 400nS(off the top of my head) set the EN signal,keep this high around 1uS (again check the actual value),read the data if you're doing a read then put EN low.

Reading the busy flag requires a bus operation - ie read the status register.

You can also keep EN high and keep reading the busy status on DB7. When the device is not busy, then you bring EN low. Personally, I don't like doing it that way - the datasheet really doesn't say it will work - even though it does is many cases.


Everybody gets tripped up on these devices - and there's heaps of bad code to talk to them out there. Best to understand and obey the datasheet.