Program can be upload only 1 time , not twice . "No target found", the second time

[Activmaker]

I made a board with H735 . I am using St-link v3 Minie to upload program. My problem is , I can upload 1 time, but not twice. To solve this issue , I boot in mode 1 , erase flash with cube programmer , and then I can upload only 1 time. Error message is "No Target Found" the second time . I suspect something wrong around Jtag/swd pin configuration, I used "device configuration tool" to configure debug pins . I used Jtag 5 pins config as I wired NJTRST . When it works , I see the program download, then verified with success , so , I think that communication between St-Link and MCU is ok . What I am doing wrong ?

[Tesla DeLorean · Accepted solution]

You want NRST, not NJTRST

The H7 is complex in that NRST can't, or rather doesn't, implement a power-on-reset, so option bytes hold over, as does mapping ROM rather than FLASH for code execution.

Watch also that you get your SMPS/LDO and VDO settings done right.

I would perhaps add some brief delay before running SystemClock_Config() to provide a window for connectivity.

Obviously anything reconfiguring the primary SWD pins, or sleeping the core.

If you get internal settings wrong, I'd recommend pulling BOOT0 High and cycling the power a couple of times until you can remove your code.

[Activmaker]

Thanks a lot, you probably find the cause , I changed configuration about SMPS/LDO ..My board is made to use LDO , not SMPS...And the configuration was set on SMPS. It seems that now I can upload many times. Good point. I will probably ask others questions here, as some lot of points are not clear for me , especially at start up. Thanks again.

[mamal]

Hi, I have the same problem as you, I designed a board using STM32L432KC according to the Nucleo-32 board.
But I succeeded in programming the chip in my board just once, for the second time it had an error "No Target Found".
I see you overcome this problem, can you tell me what to do? What is LDO and SMPS you are talking about?
is it a kind of regulator? and what should I do to solve the problem? I am using a LM1117-3.3v regulator that is a kind of LDO. So what is wrong with my board? I uploaded my schematic as well.