xeank wrote: This results in different settings for programming under Arduino when theESP8266 modules are mounted on the boards
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This is not true. The difference between the ESP8266EX and the ESP8266MOD is that the former is manufactured by Espressif and the latter is, or rather was, manufactured by AI-Thinker. Functionally, there is no difference. There is no hardware I2C controller in the ESP8266, and all communication is over I2C is done by software.
xeank wrote:
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This thread has nothing to do with processor designation, but is about software pin setting for the I2C bus.