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Information in this article applies to:

  • ULINK USB-JTAG Adapter
  • ULINK2 USB-JTAG Adapter
  • Infineon JTAG Debug Access Server (DAS)


My application works as expected on the target system without a debugger. When I try to debug my application, µVision reports error messages and the JTAG communication fails after running through some of my functions.

With ULINK, I get the following message:

JTAG Communication Failure

With the Infineon DAS, I get the following message:

No response within given timeout

What can cause this error?


These messages may have several reasons that are listed below:

  • The JTAG Interface on the XC800 device might be disabled by setting the device into Idle Mode. Please comment the expression that enables the idle mode.
    while(1) {
    #ifndef DEBUG
      PCON |= 0x01;  // switch to idle mode
  • The JTAG Interface on the XC800 device might be disabled because an alternate function has been assigned to the JTAG pins. Please check if your application modifies one of the following special function registers:
    - MODPISEL.4: JTAGTCKS selects TCK_0 or TCK_1 pin
    - MODPISEL.5: JTAGTDIS selects TDI_0 or TDI_1 pin
    - P0_ALTSEL0/1.0: for TCK_0
    - P0_ALTSEL0/1.1: for TDI_0
    - P0_ALTSEL0/1.2: for TDO_0
    - P1_ALTSEL0/1.1: for TDO_1
    - P2_ALTSEL0/1.0: for TCK_1
    - P2_ALTSEL0/1.1: for TDI_1
  • When XC800 devices works with a very slow clock the JTAG clock might be too fast. Reduce the MAX JTAG Clock in the dialog Project — Options — Debug — Infineon XC800 ULINK Driver — Settings (ULINK only) or do not lower the CPU system clock (see CMCON register).


  • Getting Started User's Guide, JTAG Debugging

Last Reviewed: Monday, August 20, 2012

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