cant access memory mapped addresses, except for private peripheral addresses.

[mohkal]

I am trying to debug the nrf9160 with the swd interface. 

I can read and write to the private peripheral addresses (0xe000_0000 and up) but i cant write or read to any other memory mapped peripheral or address.

i tried reading the ficr registers but al the registers return 0x0000_0000.

[Vidar Berg]

Hi,

I was not able to reproduce this here when debugging with the VS code extension. For instance, here is the FICR content displayed in the PERIPHERALS view:

Same when I read FICR with nrfjprog:

$ nrfjprog --memrd 0xff0000
0x00FF0000: FFAC967F

Do you have UICR.SECUREAPPROTECT.PALL enabled by any chance? This will limit the debuggers memory access as explained here: Special consideration regarding debugger access.

Best regards,

Vidar

[mohkal]

I cant read the uicr register. But when i read the ctrl-ap approtect it reads as  disabled.

[mohkal]

Via the ctrl-ap acces Port

[Vidar Berg]

Please provide more details about your setup and explain exactly how you are attempting to read the memory. I need to know if we are testing the same thing. 

[mohkal]

The ctrl-ap has registers you can read such as a reset register and Approtect register. The approtect register Should have the same value as the SECUREAPPROTECT.PALL.

[Vidar Berg]

I am asking about details about your setup on how you are reading the memory. E.g. if you are using nrfjprog, VS code, J-link, something else?

[mohkal]

Im using selfmade  debugger That  kinda works like the jlink.

can we setup a teams meeting so i can show you how  it works.

[Vidar Berg]

I am not familiar with the low-level details of the debug interface protocol. But I can ask internally why it may be failing for you if you can provide a detailed description of each step from powering on the debug interface to reading the memory.

[mohkal]

That would be Nice.

[mohkal]

I write/read to AP via the CoreSight DAP-lite protocol.

here is a link to the protocol:https://developer.arm.com/documentation/ddi0316/d/?lang=en

CTRLSTATUS=0x0;

IDCODE=0xFC;

TRANSFERADDRESS=0x04;

READWRITEDATA=0x0C;

to initialize the ahb-ap: AP-Write(CTRLSTATUS, 0x43800042) 

to perform an ahb-ap read Idcode: AP-read(IDCODE,data) data returns 0x84770001

to perform an ahb-ap read memory:

- AP-write(TRANSFERADDRESS, address)

- AP-read(READWRITEDATA,data)

to perform an ahb-ap write meory:

- AP-write(TRANSFERADDRESS, address)

- AP-read(READWRITEDATA,data)

issue: ahb-ap read/write only works on private peripherals, that are inside the cpu. but it doesnt work on normal peripheral such as NVMC.