Hello,
I'm trying to connect a BMP280 sensor and a 1602 display (both I2C) on a single Arduino uno R3 bus.
I've checked the devices when only one is connected to the board and they are both working. However, when I connect them both the display is working but the sensor shows 0 on both values. I've checked the addresses of the devices and they are different.
Can you please advise what should I do next? I've seen on some tutorials that I need to put some resistors on the circuit to work but I don't understand if this is applicable to my scenario and how I should calculate the value of the resistors.
Thanks!
Picture is worth a thousand words.
Each item works one at a time?
Yes, each device works one at a time.
I'll try to make a picture and upload a bit later.
If you run the same program with only one module connected, and that module works then when you connect both one doesn't work, it is likely a wiring issue. (not necessarily your wiring, but could be on the module).
You were right. It was the wiring which was causing problems. 
Thank you so much for your help.
One more question though...If I want to connect an RTC DS3231 module to the same I2C bus, will it work or this time I need to add something else to the circuit.
Thanks again and sorry to bother you with such noob questions.
Should work as long as the addresses are all different.