using a 5V-serial-signal on the RX-Pin of a Wemos D1, I use a voltage-divider 1,8k/3,3k to get the level at 3,3V. On the Oszi I can see, that the receiving data (going into the voltage divider) are with 5V-level.
But measuring at the RX-Pin, I only have 1V-level???
Hmmm... Ohms law tells me something different....