Dahlia Board with Verdin iMX8M-Plus: USB-C power role change

Hi @henrique.tx,

Sorry for the late reply. I was on a vacation.

We have tried couple of things but at the end, we couldn’t manage to charge iPad from Dahlia board.
I ordered TPS65987D from TI with an evaluation board.
If it works, we will try to integrate it into our custom carrier board for Verdin iMX8M-Plus.

Thank you for your help.


As a short feedback on my side:
With the tip from @henrique.tx I was able to get it to work.
On my development board I populated R433 (R18 Dhalia) with 10K (500K would be better → 1.5A) and replaced R22 (R17 Dhalia) with 10K
The current has increased to approx. 1.4A and the Ipad shows “charging” (Ipad Pro 11, 1 Gen)



Thank you for the feedback @d.baum, In our case I think we didn’t change the limiter resistor R17, I will try that tomorrow and inform.

Hi @d.baum and @Fide !

That’s great feedback, @d.baum! Thanks! :smiley:

I am looking forward to your feedback, @Fide :slight_smile:

Best regards,

Hi @d.baum and @henrique.tx,

I confirmed that iPad started being charged from Dahlia Board’s USB DRP port after changing R17 and R18 as suggested.

But USB gadget (NCM) started being invisible (non functional) on iPad.

Here is the simple explanation:

  1. When I plug Dahlia Board USB-C DRP to my notebook USB-C: USB NCM Gadget works and I see a new Ethernet interface on my notebook. But my notebook is not being charged from the Dahlia Board. That means here the Dahlia has the power role sink and acts as a device.

  2. When I plug Dahlia Board USB-C DRP to an iPad (iPad Pro 2021 M1 5th gen), the iPad automatically started being charged which is good but iPad stopped recognizing USB Gadget which means iPad became a sink device and Dahlia started acting as a Host.

What we need is that we need to charge iPad but USB gadget on the SoM as a device should continue working. So Dahlia board should act as a device and power source at the same time. And as I understand it is not possible for TUSB321 used on Dahlia board to configure USB data roles and power roles independently.


Hi @Fide !

Sorry for the delay.

I asked internally about the possibilities of TUSB321 related to data roles and power roles.

But I expect some delay in the answer as some people in Toradex is allocated to events that are currently going on.

Best regards,

1 Like

Hi @Fide !

Sorry for the delay.

In the end, seems like the TUSB321 is not the IC you need according to your requirements and I have no information about an IC that could fulfill your requirements.

I will mark the message below as the answer, as it helped you with your original question about power role change.

Best regards,