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UpBoard i2c (pin 3 & 5) - 5V devices / levels shifting

Lubo
Lubo New Member Posts: 41 ✭✭
in UP Board Hardware Specification

Hello,
I did not found if UpBoard i2c pins (3 &5 ) are able to drive 5V i2c external device directly.
It works well with 3V device ( i use 24c32 EEPROM for now ).
However, as soon as I connect level shifter and 5V devices then ( via levels shifter in the middle , one like this : https://wiki.analog.com/university/courses/alm1k/alm-lab-voltage-level-shifter ) it stop the work at all ( also 3V side 24c32 stop work too ). As soon as I remove level shifter, 3V site start to work without any issue again.
So , is 3V<>5V level shifter necessary to use, or can I drive/connect 5V devices on UPBoard i2c pins directly ?
By the other words, how to connect 5V IIC devices to UPBoard I2C ?

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  • Lubo
    Lubo New Member Posts: 41 ✭✭

    SOLVED !
    I found that reason was incorrect value for up-level resistors. I used 1k2 values for both sites (3V and 5V too).
    I changed their values to 10k at 3V site and keep 1k2 at 5V site and it works well now.

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