FS23 always reset MCU

[KidhRobin]

hello，

now  I got a issue

when I  power on the board and make FS23 not in debug mode, it always reset 

and reset line like this,

when enable debug mode , there is no reset ;

which issue can generate this behavior?

 and , in my project contains Boot project and App project,  what shall I need take care when both work with boot & application project?

[TomasVaverka · Accepted solution]

Hello Bin,

The FS23 must complete a strict initialization sequence within the 256ms INIT window. If this sequence is not completed correctly or if the watchdog is not handled properly, the device will:

- Enter Fail‑safe mode
- Assert RSTB low
- Automatically restart (if configured), resulting in the observed reset loop

When Debug mode is enabled, watchdog supervision and fail‑safe entry are disabled, which is why the reset behavior disappears. 

Please pay special attention to Figure 1: “FS23 initialization flow chart example” in our AN14041, which outlines the recommended startup sequence.

AN14129 explains the underlying behaviors and boot/application considerations

BRs, Tomas

[KidhRobin]

thanks, Tomas