How to enable the internal 1.5K-ohm pull-up resister in the USB PHY?

cancel
Showing results for 
Search instead for 
Did you mean: 

How to enable the internal 1.5K-ohm pull-up resister in the USB PHY?

436 Views
david9991
Contributor I

In IMXRT1050 reference manual it said:

56.2.5.4 Switchable 1.5KΩ USB_DP Pullup Resistor
This product contains a switchable 1.5 KΩ pullup resistor on the USB_n_DP signal.
This resistor is switched on to indicate to the host/hub controller that a full-speed-capable device is on the USB cable, powered on, and ready. This resistor is switched off at power-on reset so the host does not recognize a USB device until the processor software enables the announcement of a full-speed device. 

but hasn’t mentioned how to enable this internal pull-up resistor, and I cannot find any external pull-up resister on the board, so my PC cannot detect if device plugged in. What should I do now?

0 Kudos
5 Replies

187 Views
igorpadykov
NXP TechSupport
NXP TechSupport

Hi David

usb module controls this bit automatically internally during usb connection

procedure, seems there is no way to manually in software control it.

Best regards
igor
-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------

0 Kudos

187 Views
david9991
Contributor I

And my device does undetectable in this moment. I think USB port is just a analog detectable circuit, when the pull-up on DP or DN was detected, HOST should send the description request automatically without any other condition, even USB control not be started right? I tried use Wireshark to monitor the USB request, but nothing was captured.

0 Kudos

187 Views
igorpadykov
NXP TechSupport
NXP TechSupport

what is about other devices, USB module perform enumeration process using on own state machine,

you can try examples with i.MXRT1050 EVK and its MCUXpresso software

Welcome | MCUXpresso SDK Builder 

Best regards
igor

0 Kudos

187 Views
david9991
Contributor I

With some investigation I found the point: the RAM region have not been mark to 'shareable' in the MPU.

Thank you all the same. :smileywink:

0 Kudos

187 Views
david9991
Contributor I

But how to explain: This resistor is switched off at power-on reset so the host does not recognize a USB device until the processor software enables the announcement of a full-speed device"

0 Kudos