(Solved, see edit) I have developed an application by using STM32F4-Discovery development kit. Now code is mature and I need to build a custom circuit. In order to test that the bare circuit (according to my understanding) is working, I made following circuit: ![STM32F407 bare circuit test pcb][1] 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 idea of connecting 1uF//100nF capacitors between every VDD-VSS pin, I only connected a 4.7uF capacitor to first power line. 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 Question: --------- 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 am I missing? Edit: ------ Regarding @RBerteig's advice, I made following circuit: ![Test circuit 2][2] [1]: https://i.sstatic.net/lhV3m.jpg [2]: https://i.sstatic.net/f4U8l.jpg Difference: - There are 1uF+100nF capacitors all the VDD and GND pins (as close as possible) Problem: This circuit is still not working. I am 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.