On 02.03.2017 19:15, Thomas Irmen wrote:
unprotected chip-erase -> http://pastebin.com/EDnB8AbT
protected chip-erase (failure) -> http://pastebin.com/vcYVp18m
created with "openocd -d3 -l debug_log_proteced.txt -f
interface/cmsis-dap.cfg -c "transport select swd" -f
target/at91samdXX.cfg -c "init" -c "reset halt" -c "at91samd
chip-erase" -c "shutdown" "
So if I understand correctly you have a SAMD chip with set security bit
in NVM and you want to erase chip to remove security.T
The problem is the secure mode prevents OpenOCD to attach the device.
Actually there are more problems:
1) OpenOCD fails if device is not responsive. I commented out the error
check from command_run_line(CMD_CTX, "transport init") in openocd.c
as a dirty workaround. A correct solution would be to implement a SAMD
specific variant of connect_assert_srst mode.
2) Secured SAMD needs reset cold-plug sequence (SWCLK kept low when
nRESET is deasserted). EDBG normally issues hot-plug without CPU reset
extension. I don't know if EDBG has an vendor CMSIS-DAP command for
cold-plugging. The possible dirty solution is to apply
http://openocd.zylin.com/3103
and use CMSIS-DAP bit control:
cmsis-dap cmd 10 20 a1
cmsis-dap cmd 10 a0 a1
(now SAMD should be in extended reset)
3) Secured SAMD needs different addresses for DSU registers (DSU.CTRL at
0x41002100 instead of 0x4100200).
So 'at91samd chip-erase' command is not usable, use workaround
mwb 0x41002100 0x10
Problem 3 is easy to solve. Unfortunately 1 and 2 are not likely to be
ever fixed: SAMD DSU design is very specific and would require a lot of
changes in general infrastructure.
Please use Atmel software if you need SAMD chip security.
Sorry.
Tomas
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