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Can not read/write address 0x0 using SDP on RT1050

Question asked by Ryan Shuttleworth on Mar 23, 2018

Hello all.  I am trying to develop a proof of concept for loading a RAM based application to an RT105x via the SDP protocol.  Unfortunately, I can not use the SDP protocol to write to (or read from) address 0, the first entry of my vector table containing the CSTACK address.  I can only read and write from address (byte) 4 onward.

 

I am able to achieve what I want in an odd and indirect way:

  • I develop a RAM based "debug" application on IAR and generate a .bin file
  • I strip the first 4 bytes off of the bin file (the first entry in the vector table)
  • I write the file using SDP's WRITE_FILE command starting at byte 4 in memory
  • I connect via JTAG and write the first word of the vector table with the address of CSTACK
  • I execute from the reset entry point (and my app works)

 

I have tried SDP via the SDPhost.exe and a custom python script and the issue with address 0 exists on both.  Can anyone explain what is going on here?  I see no mention of this address restriction in the RT1050 reference manual or the SDPhost manual.  Also, attempting to R/W address 0x0 seems to result in the SDP locking up.

 

Thanks.

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