8 years, 12 months ago.

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

Hi,

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

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Last updated: 20 Apr 2021

NUCLEO-F411RE

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