I have plagiarised the Wemos D1R2 schematic (same as NodeMCU) to find out what pins to pull up and pull down. I also used info from this forum on how to connect GPIO16 to RESET with a 1K resistor. The board has a reset and program button and a header for an FT232 cable. The esp12 is placed on the non-copper side of the board with through-holes that I'm going to solder wires through. That means the board underneath the ESP12 can have tracks and components on it. Will this work? So far it's proved a bit fiddly to solder on the ESP12 in this way, but maybe with a few tweaks and some kind of jig, rev 2 will work better.
More details:
I am using KiCad to design this board.
The footprint that I made for the ESP12 has the through-holes right on the edge of the module, with the module being 16mm wide. A bit too close in practice.
It's a strange mixture of thruhole and SMD because I don't have SMD tactile switches or capacitors.
Is it worth doing this? Probably easier just to buy breakout boards, but I wanted to play around with making PCBs with the photoresist supplies that I bought.
The board is here on github: https://github.com/innesm/esp12breakout