I made a couple of arduino mini pro and esp8266 pcbs with an rs485 transceiver just to find out that I forgot to think about in-system-programming:
Assuming that I don't need to disable the transceiver i tied *RE/DE to gnd/vcc. It turned out that id do need disable the transceiver (at least the receiving part) in order to be able to program the mcu because otherwise the transceiver disrupts the serial data.
But I don't want to lose one pin for this (which in case of an esp8266 are rare) and I don't want to use jumpers because I really like the workflow without.
Is this even possible?
EDIT: The transceiver is an SP3485. Currently it is connected like:
Mini Pro SP3485
A-rx ------ RO
GND --1k-- *RE A ---- somwhere else
Vcc --1k-- DE B ---- "
A-tx ------ DI
Which blocks serial programming because of a) the "echo" and b) holding A-rx line high.
If I connect
*RE --1k-- Vcc and
DE --1k-- GND I can ISP the Arduino, but now I obviously can't use the transceiver anymore.