TPS25751: Configuration to enable USB device data

Hello,

The attached zip file contains the binary and not the json file.  You can generate the json file by selection 'Export Settings', under the 'Export' drop down menu.

What are the answers to questions 5-8?

Thanks and Regards,
Chris

Hi, 

Find attached the actual json file. As for question 5 to 8 replies:

5. USB 2

6. Device

7. No

8. No

Thanks

4454.USB-C-Test.zip

Hello,

    Do you have the ability to capture the PD logs?  I would like to see how the data role swap is handled?

    Maybe a simple test (if you have not already tried), change the preferred power role to Power Sink (consumer).

Thanks and Regards,

Chris

Don't really have the ability to check the PD logs. Also, I tried to change the preferred power role to sink but got same results. 

Hello,

    Not sure if I will be able to decode the analog, but could you take a scope capture of the CC lines during the (non-working) connection?  I will also refer to a colleague.  

Regards,
Chris

Hi Darren, 

In the customer system, do they have 15kOhm resistor pull-down on D+/D- lines? Screenshot below shows current TPS25751 configuration (Port Control 0x29). Also are D+/D- from the USB-C connector routed to TPS25751 in any fashion? From the config it doesn't seem like the customer has liquid detection or BC1.2 enabled. 

Thanks and Regards,

Raymond Lin

HI Raymond, 

I tried selecting "System has 15kOhm pull-down" but got same results. While testing again, I realized something. My custom USB device is using the PLUG_EVENT output from the TPS25751 to initialize its USB device system when the USB cable is connected. I noticed that when I plug the device to a PC, the PLUG_EVENT is given by the TPS25751. But when I plug the device to my custom made USB host, the PLUG_EVENT is not given even though my custom USB host is giving 5V supply on VBUS. 

Any idea why this could happen?

Thanks

Hello Darren,

What is happening on the CC lines?  How does the custom made USB host present Rp?

Thanks and Regards,
Chris

Hi Raymond,

Right now I am not using the CC lines. For now, they are connected to the host MCU but the host MCU CC lines are set to input and not used (will be implemented in the future when PD is added). So far, I was just trying the USB 2.0 communication. 

Hello, 

Thanks for the suggestion but I got same results. PLUG EVENT doesn't get triggered when I connect to the custom host. Note that the custom host is able to detect and enumerate other devices so I am assuming the host side is correct. Also, I have no issues when connecting the TPS25751 device to a PC using a USB-C to USB-A cable. But when connecting the the custom host using a USB-C to a USB-C cable, the issue is present. 

Hello,

I will try to use the 56k pull up to 5V for the default capability. In the mean time, I tried to measure the CC lines. I found that when the TPS25751 device is not connected, both CC lines anyway has ongoing data (don't know if this is normal or not). Figure 1 shows this,. Upon connecting the TPS25751 device to my custom host using a USB-C to USB-C cable, both CC lines go to 0V as shown in figure 2. 

On further debugging, I realized that my USB Host device was not enabling the pull-up resistors on the CC lines. Forcing this solved the issue and is now working. Thanks for the help!