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Communicate via I2C using an 8-Bit Bidirectional (TXS0108E)

Raspberry Pi Asked on January 4, 2022

I want to communicate through I2C between a Raspberry Pi 4 and an ATMega4809 (Arduino Nano Every or Curiosity).

Since SDA/SCL pins in Raspi Pi are 3.3V and in ATMega4809 are 5V I thought I had to use a logical converter, for which reason I’m trying to use an 8-Bit Bidirectional (TXS0108E).

The problem is that the logical converter seems to be quite unstable because when I have everything connected I detect on and off signal quite randomly. I’m using i2cdetect and setting up 0x18 as address:

With signal:

pi@raspberrypi:~ $ i2cdetect -y 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- 18 -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --    

Without signal:

pi@raspberrypi:~ $ i2cdetect -y 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --  

If I wire directly SDA/SCL pins I have a stable connection. However, I’m afraid that using it directly I might damage RaspiPi pins that work at 3.3V.

EDIT: schematics:

enter image description here

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