Ormgair wrote:By the way, I read that it's possible to add more GPIO, like here or here (Sorry for russian website, anyway only images are important).
I would definitely recommend buying a different module, rather than trying to hack an ESP-01.
The pins on the chip are only 0.25mm wide, so even with very steady hands and a good soldering iron with a fine tip it is rather hard to attach wires. And even if you manage to pull it off, the connections won't be very reliable.
Or it's better to buy ESP-09 (smaller and more GPIO)?
The ESP-09 is probably the smallest & lightest module available, but be aware, that it does not have an antenna.
I would rather recommend an ESP-12(e/f), it has an integrated antenna and is about the same size as an ESP-01. It weighs slightly more, but if you need to strip some weight, you could remove the metal shield.