Posted on January 23, 2017 at 16:19 
#st-link #stm32f407 #pcb-design
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Hi everybody,
I have a problem with my project. I designed and produced a PCB with two MCUs, the STMF401RB and the STM32F407VGT. I am using the ST-LINK V2 to program them and SWDIO and SWCLK. The problem that I have is that I can connect to the STMF401 but I can't connect to the STMF4 I checked the VDD and VSS in every pin and they seem to be ok. I think the design is ok but may be i missed something. I have attached the schematic that I used for the STMF4 I would be grateful if you can help me.
Thank you very much
Regards
Gregorio
#st-link #stm32f407 #pcb-design
Note: this post was migrated and contained many threaded conversations, some content may be missing.
Posted on February 07, 2017 at 11:02
I changed the power source circuit and I have 3.25V as VDD now. I measured the voltage of VDD with ST-Link and without and it is always the same ( around 3.25V). The custom board is using around 370 mA and I am using the DC/DC converter uA78M33C as power supply for the MCU. I measured everything using a DC lab power supply as well with the same results.
About using VDDA and VDD together, I followed the schematic provided by STM
I can not see here the L1 component and the 47
? that you mentioned before and VDD and VDDA are together.
About the BLACKLIGHT pin. I am not using it now. I put it in the design just because the LCD provides it and I thought i may need it in the future
Additionally I measured the impedance between the SWDIO and SWCLK and GND in my board. For the F401 the impedance is infinite between SWDIO and SWCLK and between them and GND. For the F407 between SWDIO and SWCLK is M
?, and between SWDCLK and GND is
M
? as well, but between SWDIO and GND is jus 15 K
?. I checked it in the development board and it is infinite or M
? but not
K
?. Does it mean something for you?
Thank you
