I have a Heltec wifi kit 8 with a ESP8266 in it. I also hava an arduino nano. I want to use I2C for a communication between them. The ESP8266 would be the slave who writes and receives something from the arduino nano as master. The ESP8266 works with 3.3 V and the nano with 5 V. Do i need to use a voltage regulator or voltage devider or something else or can i just connect SDA en SCL to both boards?