I use 2 MCUs as 2 I2C Masters connect with 1 Slave F-Ram to Read/Write data frequency. One MCU has internal 12k Ohm pull up resistors on SDA & SCL. So do I need external pull up resistors?
Electronic – I2C multiple masters, one master has internal pull up, do I need external pull up
i2cpullup
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Best Answer
I2C pullups are a system level consideration. You only need one pair of pullups per segment, but they should be sized with consideration for your bus load capacitance to ensure your digital signaling is sufficiently digital and your edge rates are within specifications. I always start around 2.2kOhms and adjust as necessary. 12 kOhm sounds way to high for my taste. In general an oscilloscope is handy when it comes to evaluation of I2C signal in integrity.