Software reset and RAM

RE: Software reset and RAM

tesc — Tue, 30 Apr 2019 13:09:42 GMT

Hi,

Thanks for the update. It is always good to know what happened.

Regards,
Terje

RE: Software reset and RAM

PMichael — Tue, 30 Apr 2019 09:21:02 GMT

No. I changed concept.

RE: Software reset and RAM

tesc — Tue, 30 Apr 2019 09:18:57 GMT

Hi,

This one seems to have slipped between the cracks, but for anyone still interested:

Did you find a solution to the issue?

If not, might it have been a case of code optimization leading to the variable not actually being written to memory? If so then declaring it volatile should solve the issue.

Regards,
Terje

RE: Software reset and RAM

PMichael — Tue, 22 Jan 2019 10:53:54 GMT

It also happen without debugger

RE: Software reset and RAM

PMichael — Tue, 22 Jan 2019 10:53:18 GMT

When I do it staitc

__no_init static u32 uPowernResetSignature;

In icf file

initialize by copy { readwrite };
do not initialize { section .noinit };

in map file appears .noinit section that was not before I add static

"P2", part 2 of 3:                           0xa04
.noinit             uninit   0x2000370c      0x4 SO_SystemOperations.o [1]
CSTACK                       0x20003710    0x800 <Block>
    CSTACK            uninit   0x20003710    0x800 <Block tail>
HEAP                         0x20003f10    0x200 <Block>
    HEAP              uninit   0x20003f10    0x200 <Block tail>
                             - 0x20004110    0xa04

But after software reset variable still become zero. Any ideas?

RE: Software reset and RAM

PMichael — Mon, 21 Jan 2019 19:32:37 GMT

Thank you.

this is already in link file.

do not initialize { section .noinit };

But as I wrote my variables are not static. They are global variables. I will declare static and try again..

But as I know static only restrict scope. Or I missed something? Can you advice?

ABout debuger I will try without.

RE: Software reset and RAM

tesc — Mon, 21 Jan 2019 15:34:24 GMT

Hi,

You are correct that on soft reset RAM does not change, and that the compiler will not initialize a __no_init variable.

We did something similar to this in the DFU bootloader of nRF5 SDK v11, in order to allow the application to leave messages when rebooting into the bootloader. From <sdk folder>/examples/dfu/bootloader/dfu_ble_svc.c:

__no_init static dfu_ble_peer_data_t m_peer_data     @ 0x20003F80;                               /**< This variable should be placed in a non initialized RAM section in order to be valid upon soft reset from application into bootloader. */
__no_init static uint16_t            m_peer_data_crc @ 0x20003F80 + sizeof(dfu_ble_peer_data_t); /**< CRC variable to ensure the integrity of the peer data provided. */

While I cannot explain why it did not work in your case, I have some suggestions for what to look at: Is uPowernResetSignature a global static variable? Are you sure the issue is not with the debugger? Does adding a fixed location help?

You may also want to have a look at the linker file of the SDK 11 bootloader example (<sdk folder>/examples/dfu/bootloader/pca10040/dual_bank_ble_s132/iar/dfu_iar_nRF5x.icf),I think you may need this line in your linker file:

do not initialize  { section .noinit };

Please note that I am not an expert on this, and so others may have better tips for how to get it working.

Regards,
Terje