• State Not Answered
  • Locked Locked
  • Replies 2 replies
  • Subscribers 22 subscribers
  • Views 909 views
  • Users 0 members are here
Options
Related
How was your experience today?
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

ULINK keeps controller in reset when not connected to PC

Niclas R.

Hi everybody,

I have a custom pcb with a 20-pin standard Cortex-M debug connector. The schematic of the debug interface is equal to the one on page 26 in this document:

www.mouser.com/.../Board_Users_Manual_CPU_Board_XMC4500_General_Purpo-255431.pdf

The debuggers are ULINK2 and ULINKpro. When the ULINK is connected to the pcb, but not plugged into the PC it keeps the controller on the board in reset state. Only when the ULINK is powered the controller starts running.
Why is that? Is it due to the schematic? What has to be done to prevent this behaviour?

Regards, Niclas

Parents
  • 0 in reply to Niclas R.

    For anybody that might be interested:
    the signal-drivers in the Ulink2 are kept powered by the target VCC when the Ulink is disconnected from the PC. So the reset-line is pulled low by the Debugger. Inside the Ulink2 there is a jumper that has to be switched from the ARM-position to the 3,3v-position in order to prevent that the signal-drivers are powered when the debugger is disconnected from the PC. Unfortunately the ULINKpro doesn't have this jumper so it keeps resetting the target when it is not powered.

    Greetings, Niclas

Reply
  • 0 in reply to Niclas R.

    For anybody that might be interested:
    the signal-drivers in the Ulink2 are kept powered by the target VCC when the Ulink is disconnected from the PC. So the reset-line is pulled low by the Debugger. Inside the Ulink2 there is a jumper that has to be switched from the ARM-position to the 3,3v-position in order to prevent that the signal-drivers are powered when the debugger is disconnected from the PC. Unfortunately the ULINKpro doesn't have this jumper so it keeps resetting the target when it is not powered.

    Greetings, Niclas

Children
No data