Strange I2C behaviour in V4.2 (release)

cpehonk
Posts: 6
Joined: Sat Nov 09, 2019 3:41 pm

Strange I2C behaviour in V4.2 (release)

Postby cpehonk » Sun Oct 18, 2020 3:41 am

Hi all,

does anybody encountered the following strange I2C behaviour?

I started to write a small i2c programm controlling a simple 4-line LCD display. Using the typical i2c bus speed of 100kHz leads to an extremly slow i2c communication. The complete master write cycle (using the IDF example "i2c_master_write_slave" function) consumes almost 10ms to complete a one single byte send operation. Changing the frequency of the i2c bus slightly to 150 kHz leads to a dramatic reduce down to 208 microseconds (almost factor 50 !). Does anyone have an explanation for this? What am I doing wrong with 100 kHz?

Best regards,
Christoph

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