S130 v2 Soft device size in future and protection

RE: S130 v2 Soft device size in future and protection

Jon (jono) — Thu, 14 Apr 2016 11:28:27 GMT

Hi,

Q1: thanks.

Q2: Yesterday i got hard fault with UICR.CLENR0==0xFFFFFFFF (set ram prot to 8 in _SD_INIT), i then changed UICR.CLENR0 to 0x40000 and worked around some issues with that. Today I added clearing of ram and changed back to 0xFFFFFFFF after seeing a compare to that value when stepping in mbr or softdevice. Now the verry same code (but with ram cler) that didn't work yesterday works. (I also write to NRF_MPU.RLENR0 in the keil load script to place flash alg in protected region, after loading I reset NRF_MPU.RLENR0 to 0 in the same script. Since I dont have the source to MBR and init of SD, the understanding when stepping is quite sparce... but theres somthing that I miss out here..., now i cannot reproduce the hard fault any more...)

RE: S130 v2 Soft device size in future and protection

bjorn-spockeli — Thu, 14 Apr 2016 11:15:50 GMT

Yes, if you intend to update the firmware on the chip then you should not set the CLENR0 register. Ok, so if you do a full erase of the chip and re-flash the firmware, the device does not enter the hardfault handler with the CLENR0 set to 0xFFFFFFFF?

RE: S130 v2 Soft device size in future and protection

Jon (jono) — Thu, 14 Apr 2016 10:24:33 GMT

'UICR.CLENR0 = 0x00040000' seems not to work, unclear why, end up in hard fault. Would have been nice it could work, since the chip could then have protected the ram at least...

Though, now calling 'SD_MBR_COMMAND_INIT_SD' with 'UICR.CLENR0 = 0xFFFFFFFF' does not set NRF_MPU.RLENR0 any more?? This occured first time after clearing low ram 0x20000004..0x20002800. Wether this is the true reason or not I don't know.

RE: S130 v2 Soft device size in future and protection

Jon (jono) — Wed, 13 Apr 2016 13:51:13 GMT

Hi, and thanks!

2 followups:

Do you recommend us to leave protection off? (main question)
I have confirmed this not working when run as above from boot loader. Crashes in S130 V2.0.0 @0x00019C96 on store to protected RAM (writes to addr 4, ram-protection set to 8 -> mpu fault (ram protection set by MBR on SD INIT))
Now 0xFFFFFFFF works, reason why is unclear. Could be related to clearing low ram 0x20000004..0x20002800.

RE: S130 v2 Soft device size in future and protection

bjorn-spockeli — Wed, 13 Apr 2016 13:47:45 GMT

Setting UICR.CLENR0 to 0x1C0000 will prevent you from updating the SoftDevice in the future. If the SoftDevice size increases, then parts of the SoftDevice will be located above the address set in CLENR0, resulting in that part not being able to access the other parts of the SoftDevice. The same situation will occur with the application if the SoftDevice size decreases, parts of the application will be protected against itself.

There should not be any issues with leaving the CLENR0 unset, i.e. 0xFFFFFFFF.

-Bjørn

RE: S130 v2 Soft device size in future and protection

Jon (jono) — Wed, 13 Apr 2016 13:21:15 GMT

Might be an option to disable protection by running with 'UICR.CLENR0 = 0x00040000' also? Not tried.