i2c scanner serial monitor

My pins are connected as follows; vcc-3v3, gnd-gnd, sda-A4, scl-A5.

  • Measure the voltage at SCL after the scan has been stuck. If it's LOW, the problem is probably the slave. Do you have external pullups?
    – Sim Son
    Apr 17, 2020 at 18:27
  • no I don't have any pullup resistors on hand but do you think that could be the problem
    – peterk
    Apr 18, 2020 at 2:19
  • I2C requires pullups, but sometimes, slaves already have them onboard. Can you measure the resistance between Vcc-SDA and Vcc-SCL? If it's larger than 10kOhm this can be the problem.
    – Sim Son
    Apr 18, 2020 at 2:23

1 Answer 1


Is it a 3.3 V only OLED? I suppose its vcc(OLED)-3v3(Nano).
Most OLEDs use 3.3V -5V where sometimes the 3.3V from the Arduino is not sufficient.
If its a 3.3V only OLED could you give the make of the OLED (does it have jumpers to change I2C address). Normaly the I2C scanner should return at least with nothing found.

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