Arm Mbed OS support forum

Can not detect brand new STM32F446 chips

Hey guys, I recently had a board made that uses an STM32F446, but when I connect it to my ST Link V2 it doesn’t show up. It’s a brand new chip, so I didn’t know if there was something special I had to do for it. I would love some help because I’ve been struggling with this for a long time now and I’ve exhausted all other options. I am VERY new to using these chips, so don’t hesitate to think I don’t know what I’m doing and am missing something very simple haha.

Here is what I’ve done so far:

  1. I have connected to another board that has an STM32F446 on it using the SWD pinout per the ST Link instructions thus validating the connections on my board, the connections to the ST Link and the functionality of the ST Link itself.

  2. I bought an LQFP64 socket that breaks out each pin, and placed a brand new STM32F446 from Digikey into it. I made sure I was getting good contact between the socket and the STM32 chip by using a multimeter on the ground pins, so I know the socket is good. I connected all of the 3V3 lines, the GND lines, and used the appropriate pull up/down resistors on the SWDIO and SWDCLK lines. When I connected this to the ST Link I still could not detect the board.

Is there something special I need to do before attempting to connect to the new chip through the ST Link Utility?

First of all, does your board of the test setup have any kind of clock input? That’s absolutely required for the chip to boot up. Also, I believe that this chip has a BOOT0 pin that must be grounded to tell it to boot from internal flash.

As a general rule, the best place to start for these kinds of boards is the schematic for the official dev board, which is available in Appendix A of the NUCLEO-F446RE User Manual. I’d start by hooking every pin up the same way it is there (except pins that are clearly only IO pins and don’t do anything else). From there forward you can start to make changes once you can test and see which things are really necessary, Hope that helps!