Electronic – Minimal ARM circuit is not working


I have developed an application by using STM32F4-Discovery development kit. Now code is mature and I need to build a custom circuit.

I started building the bare circuit first:

STM32F407 bare circuit test pcb

I soldered the chip on the pcb via a standard 30 Watts soldering iron with a technique like in this video: http://www.youtube.com/watch?v=6YU3v_w7x7o

Since I didn't get the point of connecting 1uF//100nF capacitors between every VDD-VSS pin, I only connected a 4.7uF capacitor to the entry point of power lines.

My pin connection is as follows:

  • VDD <- 11,19,28,50,75,100,21,22,6
  • GND <- 20,10,27,74,99
  • 2.2 uF cap is between 49 and GND
  • 2.2 uF cap is between 73 and GND
  • 10 K resistor is between 94 and GND
  • MCU.72 is connected to STM32F4-Discovery.SWD_connector.4
  • MCU.76 is connected to STM32F4-Discovery.SWD_connector.2
  • MCU.VDD is connected to STM32F4-Discovery.3V
  • MCU.GND is connected to STM32F4-Discovery.GND


I'm expecting to connect the MCU via STM32F4-Discovery's ST-Link/V2, but ST-Link utility is not being connected. I'm not able to get a heartbeat with the MCU.

What is the point I am possibly missing?


(moved to the answer)

Best Answer

Regarding @RBerteig's advice, I made following circuit:

Test circuit 2


  • There are 1uF+100nF capacitors connected all the VDD and GND pins (as close as possible)
  • Short routes

Temporary Problem: This circuit was not working. I was not able to connect it via ST-Link utility.

Solution: I checked the pins and one pin (SWCLK) was not connected to the PCB. When I soldered the pin, everything works as expected.


Here is the bare circuit schematics:

(note: isteğe bağlı means optional)

bare circuit