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Add-on OTG port hardware/register setup.

Question asked by Kai Liu on Apr 8, 2013

I have an open discussion for add-on OTG port for FRDM-KL25Z (including schematics and image). Now I find it is maybe a hardware or register setup related issue.


Hardware modification:

connecting D+/D-/GND from KL25Z USB device port,

connecting VBUS from P10 of J9 (refers to FRDM schematics), which comes from P5V_SDA after a diode.



  1. During reset, no mouse connected, D+/D- is 0V. (The host D+/D- has pull down resistor, which is correct.)
  2. When mouse is connected, D+ is 0V, D- is about 1.6V. (Mouse is LS device, D+ has pull up resistor, Why D+ is 0V? )
  3. The following transaction is hung and always bus timeout.


However the LED of mouse is refreshed because of USB reset command from host.


Attached are my source, which is clone of KL25Z-SC usb host demo. => D:\Freescale\Kinetis L Sample Code\kl25_sc_rev5\klxx-sc-baremetal\src\projects => D:\Freescale\Kinetis L Sample Code\kl25_sc_rev5\klxx-sc-baremetal\build\iar


Looking for someone to help me out. Thank you in advance.

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