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USB Multilink Cause Illegal Instruction
Robert R. Sep 29, 2016 at 04:36 PM (16:36 hours)
Staff: Gerardo R.

  • Hi, I have a system with a Coldfire MCF51JM32 in it.  I am using a USB Multilink to debug.  I came across a very strange issue in the last couple days.  I was trying to debug an interface to an SPI Flash chip.  I had had this working before but had changed the way the SPI channel was passed to the routines that handled the commands.  I got it all work, erase sector, read page, write page but when I went to do a combination of these commands all at once I started getting illegal instruction breakpoints.  This happened after I issued the erase sector command so I thought maybe I had some bad decoupling which really would surprise me as this was all working in the past.  So, I have spend the last two days checking the power, decoupling, adding some larger caps near the Flash, etc.  No luck.  I have looked at the power on the scope and seen no drops or spikes.  I went back to a previous revision we did a lot of work on that utilized the Flash and it too failed.  Finally today I tried to let the unit boot up without the Multilink attached and it booted just fine.  I could tell because the Windows computer recognized the USB which is initialized after I run the Flash test code that was failing.  So, I am at a loss to explain why the Multilink causes the code to generate an illegal instruction when connected while I am trying erase the Flash. This makes trying to debug some of the other code really difficult.  Thanks,


  • Sorry, can you provide the following so I can better understand the situation.

    -What software are you using and seeing an issue with? Also provide the version number if applicable.
    -Are you getting an error message? If so, provide the exact text of the error message and where it came from. A screenshot would be ideal.

    • Hi, I am not sure what you mean by "software version", what software?  Also, no, I do not get any error message.  The software stops running, the command window shows ILLEGAL_BP.  I can send the schematics if you like but I have the board very well bypassed.  For IDE I am running Codewarrior 6.3 on XP. I have a screen shot but how do I upload it to this discussion?  Here is the info from the about box: 

      Web: <>;
      License File: D:\Freescale\CW6.3\license.dat
      Application FLEXlm License Version: 2.000, 8.4a
      Vendor daemon: metrowks
      HI409284 (metrowks, 6.000): ColdFire ANSI-C Debug (M68k, limited by feature: 65536 bytes of code, Single User License, ANY, UNREGISTERED)
      HI409285 (metrowks, 6.000): ColdFire C++ Debug (M68k, checkout failed, demo mode: 1024 bytes of code, running in demo mode(-5), UNREGISTERED)
      No such feature exists
      Feature: HI409285
      License path: D:\Freescale\CW6.3\license.dat
      FLEXlm error: -5,357
      For further information, refer to the FLEXlm End User Manual,
      available at "";.

      • One more thing, I do not get an illegal instruction break if I do not have a break point set.  I tried running my code this morning but downloading with the debugger and then just telling it to run.  I downloaded data over the USB to the SPI Flash chip with no illegal instruction interrupt or break.  Is this issue being looked at or should I just move on?  Thanks,

  • Thanks for that information. I'd like to reproduce the issue here to see what might be going wrong, but it's difficult without having the exact Coldfire + SPI flash configuration available to test. Is it at all possible to send us a board for debugging?

    • Where do you want me to keep communicating with you?  I thought you said in the Support Request but you have not answered me in 2 days after my posts and request for more help.  I really could use some help figuring this issue out as it does not seem to be my hardware.  I will keep trying things but I am flying blind somewhat.  I wish you would respond to one of my posts.  Thanks,

  • Yes, I can but let me try one other thing first.  I am running XP on a virtual machine under VMWare Workstation.  Its been working fine up to now but I want to try my one laptop that will still run XP natively to see if that fixes the issue. I am trying to get all the software loaded to try that as fast as I can. Thanks.

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