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AR# 25244

9.1i EDK - Unable to reset MicroBlaze; "ERROR(431): Unable to STOP MicroBlaze at 0x0"


Keywords: XMD, reset, MicroBlaze, 2, multi, FPGA, JTAG

I have the following devices in the JTAG chain:

1 01e64093 10 XC4VFX20
2 020b0093 10 XC4VSX55

As soon as I connect with XMD to MicroBlaze, an error similar to the following occurs:

"Connection to MDM UART Target Failed
Connected to "mb" target. id = 0
Starting GDB server for "mb" target (id = 0) at TCP port no 1234

XMD% Error in Resetting Target
ERROR(431): Unable to STOP MicroBlaze at 0x0
UNABLE to RESET MicroBlaze"

After physically removing the first FPGA (Virtex-4 FX) from the JTAG chain, XMD works fine.


This is a bug with the 9.1i XMD where there are more than one FPGA in the JTAG chain and XMD must connect to a MicroBlaze core in an FPGA that is not the first FPGA in the JTAG chain.

A tactical patch has been created to address this problem.

1. Download the patch at:

2. Rename the XMD executable in $EDK/bin/<nt | lin> to xmd_old.exe for XP and xmd_old for Linux

3. Extract "xmd.exe" for XP or xmd for Linux into the $EDK/bin/<nt | lin> directory

This problem will be fixed in the 9.2i release of EDK.

AR# 25244
Date 02/28/2008
Status Active
Type General Article