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Electronics newbie here.

I have the following setup - three Arduino Nanos, a BME280 sensor, an MPU6050 gyroscope, a GPS GT-U7 (Goovvv Tech) module and an 128x64 (1.3in) OLED display. All except the GPS module can use/require I2C connectivity.

According to the datasheet of the BME280 anything above 3.6V is not recommended. On the other hand the OLED display and the gyroscope can work with both 3.3V and 5V. From the Arduino forum it seems that 3.3V is also what is recommended for my Nanos. Since I have different voltage and I decided to buy a breakout board of a logic level converter similar to this one from SparkFun.

For calculating the pull-up resistors I found this article from Texas Instruments..

Since I am really new to all this (I2C, calculating pull-up resistors for a bus, logic level conversion etc.) I am not sure if external pull-up resistors are required in my case. I also realize that the converter doesn't have enough channels to take care of all of my devices so an idea how to solve this (perhaps daisy chain if possible?) is also appreciated.

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  • \$\begingroup\$ "From the Arduino forum it seems that 3.3V is also what is recommended for my Nanos". if you meant the supply voltage, the atmega328 on arduino nanos' working clock, is affected by it. if they are 16MHz, they may not work correctly on a 3.3V supply. \$\endgroup\$ May 15, 2021 at 7:27
  • \$\begingroup\$ It's hard to tell from your description which of the three Arduinos connect to what sensors. But in general yes it's perfectly fine to daisy chain I2C devices. \$\endgroup\$
    – DamienD
    May 15, 2021 at 14:06
  • \$\begingroup\$ The order of connection is not important that is I can rearrange if necessary. \$\endgroup\$ May 27, 2021 at 7:59

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Apart from performance note the following:

  1. the converter has usually 10K pull-up resistors from both sides as in the following figure taken from https://www.hobbytronics.co.uk/mosfet-voltage-level-converter: enter image description here

  2. you do not need a converter for each device since I2C is a bus (you may need to use more than one per signal depending on your power assessment):

enter image description here

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