I get the below error message when I start the ULINK debugger with my KEIL MCBSTM32 eval board:
Cannot access Memory *** error 57: illegal address (0x8000000)
I've searched KEIL's website for error 57, but couldn't find anything. I've searched uVsion help, but couldn't find anything. Can someone point me to where these types of errors are documented?
The debugger is actually stopped at address 0x80001A4, and these are the instructions before and at that line:
0x080001A0 F002BBF6 B.W 0x080002990 0x080001A4 4804 LDR r0,[PC,#32] ; @0x080001C8
and this is what's at 0x080001C8: 0x080001C8 00ED LSLS r5,r5,#3
and this is what's at 0x08002990: 0x08002990 4770 BX lr
Address 0x8000000 is the start of flash ROM for the uC on this eval board (an STM32F103RBT6). I'm using the default KEIL assembly startup code (STM32F103x.s) and the default project options for where ROM and RAM is (IROM1 at 0x8000000 with size = 0x20000, and IRAM1 at 0x20000000 with size = 0x5000).
If I start the debugger then stop it, I get this error message:
ULINK - Cortex-M Error Could not stop Cortex-M device! Please check the JTAG cable
I found some knowledgebase articles that suggested slowing down the JTAG clock, using internal or external 3.3V inside the ULINK, and/or making sure that a hardware reset was used with the ULINK; so I tried those suggestions. Unfortunately, they didn't change my symptoms.
I've been trying to find somwhere where I could insert a breakpoint to try to step through the startup code, but uVision won't let me put a breakpoint anywhere in the startup assembly code (and yes, I do have the "Debug Information" checkbox checked in the project options). I've unchecked the debugger "Reset and Run" and "Run to main()" options, but when I start the debugger and try to single step, I can only step a few times and then the code appears to start and never stop. If I hit the "halt" button, I get the same error message about not being able to stop the uC.
The debugger always starts at address 0x080001A4 with the error message about not being able to access memory.
Can anyone suggest something else to do that might fix these problems?
Thanks, Dave.
I don't know much about this, but I am really curious about such a problem.
I have an assumption. (Sorry for my limited technical ability and limited English ability.)
[ I did try the Blinky project, and it worked. ]
Maybe, when your specific application is running, the MCU enters a specific status, so that the MCU can not be halt/reset properly.
If this is the case, then, after you fully erase the program on the MCU, the problem should disappear for once.
John,
Since I can't even execute the 1st line of code when I have this error, I don't see how it could be my app's fault that the debugger won't run.
But, I went ahead and tried your suggestion anyway after re-enabling "Download to Flash" under "Download Options" in the "Cortex-M Target Driver Setup". As soon as I did that, my error 57 problem re-appeared. I then manually erased the flash ROM and tried to start the debugger again, but error 57 came right back.
There are over 70 source files in my project. I'll try putting them into the blinky project and see if that does anything.
Dave.