Hello,
I have a problem with option bytes programming on microcontroller STM32F401CB.
At first we were using ST-Link to program this device, including option bytes and it worked. Then we have to use more industrial programmer so we chose Flasher ARM.

So problem is that erasing, programming and verifying works OK, but option bytes are not programmed, despite the output of JFlash says: De-initializing CPU core (Exit sequence) ... - De-initialized successfully
If i check it with ST-Link, option bytes are still in default state.

I've read about option bytes programming in JFlash manual, so I checked correct values in STM32F401 manual, and I belive Exit sequence is correct STM32F405OE_OptBytes3.jflash (see attached file).

Thank you for your help.

Jiri

Hi Niklas,

is screenshot.

ST-Link is not connected during JFlasher programming. I have ony one cable, so I have to switch it between ST-Link and JFlasher.

Before ST-Link check, I power down and power up target board.

UPDATE:

Finally, I figured it out! Thank you for the J-Link logfile feature

Problem was, that I set option bytes register to value 0x0FFFFF25 -> but that causes that I accidentally lock this register, so next operation was not performed. So I changed register value to 0x0FFFFF24 and it worked.

Jiri