USB DFU not visible without ST-LINK connected

[tom239955_st]

Posted on April 10, 2017 at 14:24

I am using STM32F303CCT6 on my own board. During testing I noticed that USB DFU works fine and is detected by the PC, but ONLY when the ST-LINK/V2 is also connected ... When it is not connected the DFU does not show up on my PC?

I performed a sanity check and my code runs as expected without the ST-LINK/V2 connected, its just that the USB DFU is not found be the PC without it ...

Any suggestions or things to check?

Regards.

T#dfu #usb #stm32f3

[Tesla DeLorean]

Posted on April 10, 2017 at 22:26

[tom239955_st]

Posted on April 11, 2017 at 11:36

I have corrected the NRST wiring and that has not solved the problem.

However, I took your second advice about jumping the ST-LINK and I have found that when both the TVCC 'AND' SWIO pins are connected the PC sees the DFU ....

Any thoughts?

[tom239955_st]

Posted on April 11, 2017 at 15:11

I have found a solution to this .... but seen nothing in any of the documentation!

I have pulled-up the TMS/SWIO pin to +3V3 using a 10K resistor. The PC now sees DFU mode and the ST-LINK still can program the MCU.

[Uwe Bonnes]

Posted on April 11, 2017 at 15:44

What about RM0316 Chap. 33.4.3 'Internal pull-up and pull-down on JTAG pins'

There is a clear statement that TMS has an internal pull-up. Probably you have a load on your TMS pin, pulling down.

[Tesla DeLorean]

Posted on April 11, 2017 at 17:49

Less confusion when schematics provided