Hi josephxavier,
About the startup sequence, if you find a kinetis sample code, it doesn't difficult to understand.
1. POR and the chip is reset
2. enter in the Reset_Handler, which you can find it from the .s file.
take KL25 KSDK1.3.0 sample code as an example.
Reset_Handler
CPSID I ; Mask interrupts
LDR R0, =SystemInit
BLX R0
LDR R0, =init_data_bss
BLX R0
CPSIE I ; Unmask interrupts
LDR R0, =__iar_program_start
BX R0
PUBWEAK NMI_Handler
SECTION .text:CODE:REORDER:NOROOT(1)
3. enter the SystemInit function.
this function will have the disable watchdog code and the clock setup code, for details, please refer to the sample code.
4. enter init_data_bss function
this function is make necessary initializations for the RAM
5. enter main function, which you can find it from __iar_program_start
Besids, in the K series and KL series quick reference, there still have some startup routines description, you can refer to it.
http://cache.nxp.com/files/32bit/doc/quick_ref_guide/KQRUG.pdf?fpsp=1&WT_TYPE=Quick%20Reference%20Gu...
chapter 1.1.4.2 Startup routines
Wish it helps you!
If you still have question, please contact with me!
Have a great day,
Jingjing
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