Thank you for your more details!
Actually, we have a lot of I2C sample code for FRDM-KL03 in our SDK_2.0_FRDM-KL03Z, please download it from this link:
kex.freescale.com/en/welcome
Choose FRDM-KL03 in the board, then generate the KSDK2.0 package.
After you download it, you can find the I2C sample code in folder :SDK_2.0_FRDM-KL03Z\boards\frdmkl03z\driver_examples\i2c
Please refer to this code and test it on your side.
If you still have question after refer to the KSDK2.0 I2C sample code, please let me know!
Have a great day,
Jingjing
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