topic Re: IMX6UL, enable pullup on USB_n_DP in i.MX Processors

IMX6UL, enable pullup on USB_n_DP

bobosv — Mon, 22 Feb 2016 14:32:52 GMT

I would like to enable the pullup on USB_1_DP on an IMX6UL

(for charger detection)

I can find the pullup resistor in figure 66-2 of the datasheet, which shows the 1500 ohm resistor connected to DP pin.

The control signal is named 'RPU_ENABLE'

I can not find this control signal in the register!!

How do i enable this pullup??

/Bo

Re: IMX6UL, enable pullup on USB_n_DP

gusarambula — Tue, 23 Feb 2016 18:47:18 GMT

Hello bo sv,

You would need to first enable the override control of the USB_DP on the bits USBPHYx_DEBUGn[ENHSTPULLDOWN] and then control it with bits USBPHYx_DEBUGn[HSTPULLDOWN]. Please check Section 56.3.6 of the i.MX6UL Reference Manual.

I hope this information helps!

Re: IMX6UL, enable pullup on USB_n_DP

bobosv — Wed, 24 Feb 2016 09:07:58 GMT

Hello Gusarambula!

Thank you for your reply, i checked your suggestion, but to me, those bits seem only control the pull down available on the USB transmitter PHY

ENHSTPULLDOWN: Set bit 5 to 1 to override the control of the USB_DP 15-KOhm pulldown.

Set bit 4 to 1 to override the control of the USB_DM 15-KOhm pulldown.

Clear to 0 to disable.

HSTPULLDOWN Set bit 3 to 1 to pull down 15-KOhm on USB_DP line.

Set bit 2 to 1 to pull down 15-KOhm on USB_DM line.

Clear to 0 to disable.

To me that is the two lower 15000 ohm resistors in Figure 66-2, I want to control the 1500 ohm resistor above those, connected to RPU Enable...

The datasheet mentions that this is what should be done to detect a dedicated charger, in the chapter 66.2.7.3, Charger Detector!

/Bo

Re: IMX6UL, enable pullup on USB_n_DP

bobosv — Wed, 24 Feb 2016 12:52:18 GMT

Now i found the correct bit!!

I disabled the ENHSTPULLDOWN and HSTPULLDOWN as you suggested Gusarambula

Then i enabled the bit ENDEVPLUGINDETECT

ENDEVPLUGINDETECT

For device mode, enables 200-KOhm pullups for detecting connectivity to the host.

That seems to work formy purposes!

/Bo

Re: IMX6UL, enable pullup on USB_n_DP

gusarambula — Wed, 24 Feb 2016 18:14:29 GMT

Hello Bo Sv,

I'm glad you found the information! Thanks for posting your findings! I'm sure they will help other users.

Just for reference, I would recommend checking for the latest documentation available since the figure you shared is now Figure 56-1 of the latest revision of the i.MX6UL Reference Manual. (I wanted to leave this information on the post in case other users may need to find the image on the document).

Regards,