ESP8266 Community Forum

internal flash ( i can use it with other devices using another pins as SS ) and another one on pins 12,13,14,15.

Honestly I don't know enough about it. I did think that a SD card in 4 bit mode might work (what I was interested in) but the information I read about it eliminated that possibility. https://github.com/esp8266/Arduino/issues/4298

Do some searches on HSPI and see what you find.

HSPI can be used with one additional device where the priority is on flash chip, so transfer may be interupted.

article on freeing gpio9/10 this ofcourse works on ESP-12 also once cap is removed...

schufti wrote:HSPI can be used with one additional device

Sweet, I didn't know that; thanks @schufti, I'll keep that in mind when struggling with not having enough I/O again.