Hi Jan,
Yes, you should better find a TTL-USB tool, and connect it to P4.
This is my test result with flash Magic:
1. Modify the SDK2.2 flashiap code, Chip_IAP_ReinvokeISP, which I already post before.
Main code:
int main(void)
{
uint32_t i, status;
unsigned int t1=0,t2=0;
/* Board pin, clock, debug console init */
/* attach 12 MHz clock to FLEXCOMM0 (debug console) */
CLOCK_AttachClk(BOARD_DEBUG_UART_CLK_ATTACH);
BOARD_InitPins_Core0();
BOARD_BootClockFROHF48M();
BOARD_InitDebugConsole();
Chip_IAP_ReinvokeISP();
while (1)
{
}
}
2. Then open the flash magic

You can find the UART ISP works.
Now, you can generate the app.hex file, and put it in the step 3, I use the sdk gpio code as the app.
3. Download the code

4. After download code, press Go,

Then you will find your app works.
Have a great day,
Kerry
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