I want to build a level shifter circuit for the RX pin of my ESP-12S. The goal is to convert any level between 3.3V and 5V to 3.3V as I might use many USB to UART breakout boards with different output pin level. I tried the divider solution:
But it won't work for 3.3V input as the voltage will drop to a value that's below the minimum acceptable voltage for a logic "1". I want to keep the solution as simple as I can, and I do not want to use level shifter chips. What can I do? Thanks for suggestion.