Unable to flash STM32F401RET6 from ST-Link Utility or STM32CubeIDE

dreamcoder · ‎2022-01-24

I have successfully tested a prototype with the Nucleo F401 board and I have now moved the design to a custom PCB but I cannot program the microcontroller. The microcontroller STM32F401RET6 is not detected in the ST-Link Utility tool or in the STM32CubeIDE. The 3.3V is supplied to the MCU correctly. There are no peripherals connected to the board at the moment.

Did I miss any connection here?

I have tried these: connect VBAT to 3V3, changed C7, C8, C9, C10 to 100nF, changed C12 to 4.7uF for VCAP1.

The MCU is still not detected and I tried with my second board too. This rules out the MCU being broken.

Peter BENSCH · ‎2022-01-24

Welcome, @Community member, to the community!

At first glance, it looks essentially good.

Only C18 is a bit small with 4.3pF, you should better use 100nF there.

What debug hardware are you trying to connect to the target?

Are you sure you connected the cable or connector correctly?

Regards

/Peter

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dreamcoder · ‎2022-01-24

Thanks @Peter BENSCH , I am not really using the reset button but in any case, I have changed the C18 to 100nF on my board. I am using the STLink V3 to connect to the target. The cable and connector should be fine since I am using the similar connector on another board with STM32F405 controller and I can always talk to this controller. So the cable, connector and the debug tool are all good.

dreamcoder · ‎2022-01-24

if this helps, the voltage readings on various pins are: Reset: 3.3V, Boot0: 0V, Vcap1: 1.13V

Peter BENSCH · ‎2022-01-24

Voltages are ok.

I can't find any noticeable error in the circuit. Do you happen to have other prototypes with the same structure that you can use to verify this?

Regards

/Peter

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dreamcoder · ‎2022-01-24

Are there any other things I could check?

dreamcoder · ‎2022-01-24

Yes, I tried this on the second board that I made and I cannot detect the microcontroller in this one either.

Peter BENSCH · ‎2022-01-24

Well, if the layout might not be correct, the second board will behave the same way.

Are you sure the STM32F401 are genuine and not fakes?

Regards

/Peter

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TDK · ‎2022-01-24

VBAT needs to be connected to VDD.

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dreamcoder · ‎2022-01-25

Connecting VBAT to VDD did not change anything. I still cannot program the STM.