Wemos D1 mini pin out

 as 2025 I still have lot of D1mini, old but still good.

But the pin labeling is terrible. Here is the exact GPIO Nr

from here

the yellow pins are to avoid since it's used on start up.

So, only the green ones are super safe to use:

example:

for softseial should define GPIO5(D1) with GPIO4(D2)

if you use softserial example, most of them use 2 and 3, which will not work