All the 485 transceivers I have looked at need a TE. High when data is valid and low when it inst.
There are a couple of 555 circuits out there which toggle TE but they all have issues, of one form or another.
If you are going to implement something which is 'only' a hardware standard you might as well do it right 
Library ... I fancy a half duplex bus that will work Master-Master, using dominant byte collision handling like CanBus but with 485 electrical resilience.
Al