HD3SS3220: Unexpected VBUS detection while connecting Type A-C cable only

Lidong:

   sorry to reply late due to holiday in US. Did you forget to attach FIG A and B?

Regards

brian

CC pin will toggle when configured as DRP, do you configured as DRP n default in I2C mode?

>CC pin will toggle when configured as DRP, do you configured as DRP n default in I2C mode?

As I described in 1st comment, we're tying PORT pin to GND to configure it as UFP mode.
Do we need to have any other setting (ex. register setting) to disbale DRP mode?

In I2C (ADDR is high or low) mode ,  default is DRP mode. You need to change mode to UFP after power on.

Regards

Brian

>In I2C (ADDR is high or low) mode , default is DRP mode. You need to change mode to UFP after power on.

How can I cahnge to UFP mode?
I tried to set 0x10 to General control register (I2C offset=0x0A, [5:4] MODE_SELECT=2'b01 (UFP mode)),
but I still see CC pin toggled.
The datasheet says that the MODE_SELECT can only changed when in the unattached state.
What does it mean? What operation should I do?

did cable connected when you tried to change mode in I2c?

I saw the symptom in both case.
1. Cable not connected => I2C mode change => connect cable => VBUS detected
2. Cable connected => I2C mode change => VBUS detected

sorry, I mean when Cable not connected , I2C mode can be changed from DRP to UFP?

any update?

Hi, I was referred to here by Lidong-san,

>I mean when Cable not connected , I2C mode can be changed from DRP to UFP?
Does it mean if I can write 0x10 to General control register (offset 0xA) via I2C when cable not connected? if so, yes. I can set 0x10 and the read back value was also 0x10. but after setting 0x10, if I attach type A cable, I saw CC pin toggled. Is it not expected behavior?

Regards,
Wakasugi

The following list describes the steps for enabling UFP through I2C:
1. Write a 1'b1 to DISABLE_TERM register (address 0x0A bit 0)
2. Write a 2'b01 to MODE_SELECT register (address 0x0A bits 5:4)
3. Write a 1'b0 to DISABLE_TERM register (address 0x0A bit 0)

Regards

brian

Hi Brian-san,
Thank you for the response. I tried your sequence, but I still see CC1 toggling after step3, and still see unexpected VBUS detect.
Attached waveform of each step.

USB_CC1_pin.pptx

Regards, 
Wakasugi

Wakasugi-san:

     After above changes, can you read back what 0x0A value is?

    Can you try GPIO mode (ADDR=NC) to see if CC pin still has clock signal?

Regards

Brian

Brian-san,

>     After above changes, can you read back what 0x0A value is?
0x10.
In every step, I confirmed that the write value was correctly written in 0xA register by readback.

>    Can you try GPIO mode (ADDR=NC) to see if CC pin still has clock signal?
I will try. thank you

ok, let me know when you have test result.

Regards

Brian