ESP8266 Community Forum

Hi, I need to connect 4 buttons and LCD to my ESP8266 e12. I have LCD 2004 with I2C interface attached to it and I have I/O extender pcf8574. My concern is that I need to power LCD with 5V and probably the extender as well? Then if SDA and SCL won't burn mine ESP from those peripherals? I have seen on internet people connect LCD normally to 5V (thorough I2C interface) and hook up I2C directly to ESP without any problems.
I came across this: http://vito.tw/wp-content/uploads/2016/ ... -I2c-4.png
and he is using FETs to lower the voltages, is it necessary? Maybe some resistor would be enough?

I guess now that I need different addresses for two I/O extenders? So one A0 pin should be pulled high

Of course !
Or you can purchase 16 ports expander version, PCF8575 or MCP23017.
For voltage level shifter, you must use the MOSFETs, because I2C is bidirectional, resistors are not enough.