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I have an ACS712 (5v sensor), an ADS1115 (5 or 3.3v) and an ESP8266 board (3.3v).

I know I can't directly use the ACS with the ESP without a voltage divider on the analog pin. So I figured I could run the ADS and the ACS off 5 volts as the ADS communicates over I2C. Does this cause any issues with the SDA/SCL lines on the ESP?

What is the correct way in going about this?

  • The I2C lines of of ADS1115 will use 3.3 V if you power it with 3.3 V, but then the maximum analog input voltage would be 3.6 V (VDD + 0.3 V). – Juraj Oct 8 at 5:09
  • i am aware, but that wasn't my question – Alex Oct 8 at 5:18
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The SDA line of of ADS1115 will use 3.3 V if you power it with 3.3 V, but then the maximum analog input voltage would be 3.6 V (VDD + 0.3 V).

The ACS712 has the middle value at 2,5 V so to read it you need the 5 V range and must power the ADS1115 from 5 V. Then the SDA line of esp8266 will be connected to 5 V logic level, but the esp8266 pins can handle 5 V TTL communication currents.

The SCL line is driven from master (esp8266) at 3.3 V and the ADS1115 is good with it.

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