Hi junwang,
If you want to use uart to download the code to the KL26, you need to use the UART flash bootloader program, then relocate your application code.
For details, please refer to our kl25 kinetis bootloader 2.0, which can be downloaded from this link:
Kinetis Bootloader|NXP
You can find the kl25 uart bootloader from this folder:NXP_Kinetis_Bootloader_2_0_0\targets\MKL25Z4
More details, please refer to document in :NXP_Kinetis_Bootloader_2_0_0\doc
Besides, we still have the application note about the uart bootloader:
http://cache.nxp.com/files/microcontrollers/doc/app_note/AN2295.pdf?fsrch=1&sr=1&pageNum=1
an2295sw:
http://cache.nxp.com/files/microcontrollers/doc/app_note/AN2295SW.zip
Wish it helps you!
If you still have question, please let me know!
Have a great day,
Jingjing
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