Why the stusb1600 on board STM32MP1157C-DK2 can't sink power?

[zqizh.1]

Hi,

I flashed OS "en.FLASH-stm32mp1-openstlinux-5-4-dunfell-mp1-20-11-12.tar.xz" to board STM32MP157C-DK2.

Then remove all the cable,and only remain a type C cable connected with my laptop Type C port.

But the kit can't power on.

Could you tell me how to let it to sink power as USB device,and source power as USB host?

Thanks,

QiZhang

[Fee]

Hi,

on the DK2 only the connector cn6 is used for powering the board (the one next to the network jack). Be aware that this jack is only for powering the device so the data lines are not connected! These are only connected on connector cn7 (the one next to the USB type A ports). In your case you seem to need a second cable for powering the DK2 board. See also the schematic: https://www.st.com/content/ccc/resource/technical/layouts_and_diagrams/schematic_pack/group0/36/8e/ea/7a/ca/ca/4b/e4/mb1272-dk2-c01_schematic/files/MB1272-DK2-C01_Schematic.pdf/jcr:content/translations/en.MB1272-DK2-C01_Schematic.pdf

[zqizh.1]

Hi,

If like that , Could you tell me why need to mount IC STUSB1600 on the board?

Please advise,

Thanks,

QiZhang

[Fee]

You will have to ask someone from ST why they decided to use it. If you are building a custom board the usb doesn't need this chip to work, so it might be something due to USB type C support but I dont't know in detail.

[PatrickF]

I confirm that you cannot supply the DK2 board using CN7. Having done that would have imply to add USB certification as 'Bus powered device' (because there is no battery supply like in a chargeable portable device) which would have added unwanted complexity for a Discovery board.

Note also that CN7 could be used as USB host (not sure it is automatically switching on Starter package).

The STUSB1600 is used to show how to manage the CC lines to being able to advertise as Dual-Role Data for Type-C as well as being compliant with the USB standard requirements. As you pointed, not all of its feature are used, but the DK2 could be used as a start point for a more complex custom device involving sink path.

Regards.

[Olivier GALLIEN]

Hi @zqizh.1​ ,

Thanks for you participation in this community !

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Olivier