8 years, 5 months ago.

Custom STM32F411 based PCB without ST-Link, 20 minutes to bootup


I have been trying to get my custom PCB based on Nucleo F411 [exact replication of F411 side of Nucleo board] working since a few days now, it does not have ST-Link programmer onboard as I would be re-programming it very rarely once it is setup. So what happens is, the program loads up fine and runs properly even after reset (pressing the reset switch) but when I power it off and back on, the program does not start up. To verify if the program is still in the memory, I used the ST-Link tool and performed a memory check which turned out ok.

While debugging using a Nucleo 411 board [MB1136 C-02] I realised that the MCO line is connected from the ST-Link to the F411 via SB16 and SB50. The moment I remove either of these jumpers, I am able to replicate the same behaviour on the Nucleo board. I beleive the F411 keeps looking for a clock source to startup and eventually turns to its internal oscillator, and this is roughly after 20 minutes. After this if I press the reset switch, it reboots immediately and works fine.

It is interesting to note that an older Nucleo F401 board [MB1136 C-01] has these jumpers [SB16, SB50] alongwith the 32k X2 crystal absent by default.

I am wondering if there is a way around this, ideally there shouldnt be a need for ST-Link to be present on all boards, right? Would really appriciate if someone can post a solution to this.

Thanks! Akash

Question relating to:

Affordable and flexible platform to ease prototyping using a STM32F411RET6 microcontroller.

1 Answer

8 years, 5 months ago.


messed up systick timer waits 20minutes for HSE to be ready. When you press reset, it goes stright because AHBPrescTable is already at its ram location.

Accepted Answer

Wow that worked, thanks Geremia! Is there any way we can report this to the mbed team and have it updated in their next release?

posted by Akash Vibhute 22 Apr 2015

Hi, nice bug, eh?:) I sent pull request on github yesterday.

posted by Geremia G 22 Apr 2015

Hi, I had the same problem too and I'm trying to fix it. Do you know where to open the "system_stm32f4xx.c" file in the mbed online complier?

posted by Zach Wang 22 Sep 2015