I'm familiar with connecting a RS485 transceiver with a separate DE wire. However, on this pi hat, they used just Rx and Tx, and I'm not quite sure how it works. (or does it work?)
Looks like the transceiver switches to Tx with each transmitted 0, and then immediately goes back to Rx mode? Wouldn't the bus enter some kind of 3-state mode then, instead of sending 1? Or is this some hack with the gate capacitance?