lpcware

Why OHCI not response when USB_OVRCR state change

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 18, 2016 by lpcware
Content originally posted in LPCWare by new_user on Fri May 13 08:35:19 MST 2016
Device: LPC1768

[u]Test 1[/u]

Action: I connect wire from USB_OVRCR to ground
What happen:
[list]
  [*] USB_OVRCR pin state change: 1 => 0
  [*] OcRhPortStatus1 change: 0x00000100 => 0x00080000
  [*] USB_PPWR pin state change: 0 => 1
[/list]
=> Overcurrent protection work. OHCI  automatically turn USB port power off.


[u]Test 2[/u]

Action: I connect write from USB +5V pin to ground (real overcurrent situation)
What happen:
[list]
  [*] USB_PWRD pin state change: 1 => 0
  [*] USB_OVRCR pin state change: 1 => 0
[/list]
=> That's all. Overcurrent protection not work. OHCI not response at all (OcRhPortStatus1 is still 0x00000100).


Is this normal? Why OHCI not response test case 2?

Outcomes