Hello Jerome Brillant,
Actually, the 9 bit is very simple, you can find the according information in the KL46 reference manual:



About the configuration, you can use the register to control it directly.
UART1_C1 |= UART_C1_M_MASK;
Wish it helps you!
If you still have question, please let me know!
Have a great day,
Kerry
-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------