Demo does not work, PDOs are requested but not selected.

[nikolai2111]

Hello,

I am currently working on a project for my bachelor thesis. It is a USB-C PD laboratory power supply. I am currently on the home straight.

Unfortunately, I couldn't get your demo project to work. Because the two devices can't agree on a PDO, or a PDO is requested but it never happens. See picture below. This is the output over the UART:

This is the voltage on the VBUS:

And here is the output of the STM32CubeMonitor USB-C PD:

Can you help me? I'm planning to open-source the project when it's finished, so your usb-pd part would be perfect.

[Ralim]

Hia, To confirm are you using a black pill board with all the IO wired up as mentioned in the Readme? When I last updated this project it was working to request a connection. You may have a power supply that advertises 21V max in the PPS profile but cant supply it. Try disabling this if block section https://github.com/Ralim/STM32-USB-PD-Demo/blob/58fcba925cb40cd79dd307f3b30fd32ffb364d06/Workspace/USBPDDemo/Core/user/PDUser.cpp#L98

If that is the case, just limit the max requested voltage to 20V

[nikolai2111]

Hello,

Thanks for your fast response. No I'm not using a Black Pill Board, I'm using an own Board. But I'm pretty sure the connection are right, because I tested them already.

I have tested the program without the "else if" statement which you suggested, but no success.

Could it also be a malfunctioning interrupt, because I misconfigured something?

[nikolai2111]

Edit: I also tested if the interrupt comes through, and it does. When I plug in the connector I will land in this function. So I'm sure the hardware is working correct.

https://github.com/Ralim/STM32-USB-PD-Demo/blob/58fcba925cb40cd79dd307f3b30fd32ffb364d06/Workspace/USBPDDemo/Core/user/PDUser.cpp#L56

[nikolai2111]

The Log on the UART-Interface with the PD_DEBUG_OUTPUT defined. Looks like the following:

Starting
FUSB Comms OK
>Running thread
Current state - PESinkDiscovery
Current state - PESinkSetupWaitCap
Waiting for events 0023
>Waiting for events
>Running thread
>Waiting for events
>Running thread
>Waiting for events
>Running thread
>Waiting for events
Notification received  0800
Notification received  0002
>Running thread
Current state - PESinkWaitCap
Wait Cap Event 0802
Source Capabilities message RX
Current state - PESinkEvalCap
PD slot 0 -> 5000 mV; 3000 mA
PD slot 1 -> 9000 mV; 3000 mA
PD slot 2 -> 12000 mV; 3000 mA
PD slot 3 -> 15000 mV; 3000 mA
PD slot 4 -> 20000 mV; 5000 mA
Found desired capability at index  4, 20000 mV, 5000 mA
Current state - PESinkSelectCapTx
Sending desired capability
Starting message Tx - 02
Message queued to send
Waiting for events 0E01
>Waiting for events
>Running thread
>Waiting for events
>Running thread
>Waiting for events
...

Edit: It looks like the device gets detached, with both USB-C sources I have.

[Ralim]

So the uart logs show that it is attempting to send the message back but your not seeing it in your logger. Are you able to capture the I2C bus traffic?

[nikolai2111]

Yes, I captured it today. I started the capture, then reseted the device, then plugged in the USB-C cable.

USB-C_PS_I2C-Log.txt

The circuit diagram looks like this. I have placed R401 as it does not work, but I have in mind, that this Connection to VBUS is not needed. Is that correct? A 220pF capacitor is connected to each of the CC lines.