Which registers in the UICR of the nRF5340 are reserved for user access?

[Palmer Huang]

As far as I know, UICR->OTP should be similar to the UICR->CUSTOM register in the nRF52 series. However, I have learned that the nRF Secure Immutable Bootloader (NSIB) writes some parameters to the OTP registers. So, I would like to know which registers are reserved for user access?

[Naeem Maroof]

Hi Gray,

Thank you for contacting DevZone at NordicSemi.

We have bootloader storage library described here: 

The bootloader storage library is used to read and write both one-time programmable (OTP) data and a non-volatile counter. If the nRF Secure Immutable Bootloader (NSIB) is enabled, it should be the only user of this library. The application image can only include this library when the NSIB is disabled.

The library uses either the OTP region of the User information configuration registers (UICR), when present on SoCs like the nRF9160 or nRF5340, or the internal flash memory. When the library uses the internal flash memory, the bootloader blocks the write access before booting the next image.

Regarding nrf5340, UICR is present both in the Application core and in the Network core.

writes some parameters to the OTP register

which parameters you are referring to? Can you share more details / link of the information.

On the network core of nrf5340, UICR.Customer[n] (starting at 0x01FF8000 + 0x300  address) are reserved for customer.

On the application core, UICR.OTP[n] (starting at 0x00FF8000 + 0x100 address) are one time programmable (RW1).

Please refer to nRF5340 Product Specification for more details.

Regards,

Naeem

[Palmer Huang]

Hi, Naeem

Naeem Maroof said:

which parameters you are referring to? Can you share more details / link of the information

My purpose is to find an area reserved for customers in UICR to write some parameters. For example: I want to write mac address, token value, key, etc., which will not be modified in the application.

On the application core，between NRFCPINS and OTP registers, there are still some addresses that are not used (0xff8028~0xff8100)?  Are these reserved for customers?

[Palmer Huang]

Hi Naeem,

Can I set the provision area on the internal flash like nrf52x, so that all OTP registers are used by customers?

The current partition is as follows:

In addition, I don't understand why nrf5340 does not set provision on flash by default.

[Naeem Maroof]

Hi Gray,

Apologies for delayed response. 

I have asked internally about it, and will update you once I have more information.

Regards,

[Palmer Huang]

Hi Naeem, any updates on this?

[Naeem Maroof]

Hi Gray,

I did not get any useful information, and I don't know the answer to your question.

Can you try to elaborate what you are doing currently and what you want to do?

If you could provide some example (code / commands) for better information and understanding of the issue, it would be good. 

[Palmer Huang]

Hi，Naeem,

I am using nrf5340 to develop a product, and I need to write the MAC address, sensor parameters, keys, etc. into UICR, and the length of these data is about 512 bytes. What I want to ask is which register should I write these data to?

[Naeem Maroof]

Hi Gray,

Both of the application and the network core (on nrf5340) have their own UICR registers.

Application Core UICR are not accessible from the Network core.

For writing to UICR registers, please see NVMC controller. 

App-core UICR base address is 0x00FF8000, and its OTP offset is 0x100.

Within the OTP region, there are 192 4-Byte registers which you can use to write your data values.

I have just compiled the Provisioning_Image sample, and I can see the following memory report.

[Palmer Huang]

Hi Naeem，

Sorry, my previous description might not be very clear.
I can understand that the OTP area (0xff8100~0xff83fb) is writable, but since I need to upgrade mcuboot, I enabled nRF Secure Immutable Bootloader(NSIB). Then after compiling, I saw that some registers of OTP (Provision partition) are occupied in NSIB, can you help me determine whether there are only 31 4-Bytes registers left available?

If yes, it is not enough for me, the parameter I want to flash is more than 31*4 bytes, can I move the Provision partition to the flash? Like the nRF52 series. If possible, can you provide an example?

[Naeem Maroof]

Hi Gray,

Thank you for clarifying that you are using NSIB.

NSIB implements ROT (root of trust) for secure boot chain, and using NSIB the public key hashes are written to the device (called provisioning)

On nrf5340, provisioned data is held in the OTP region instead of the internal flash memory, so that is why only some of the registers are available for user.

I could confirm that 640 bytes from the otp are used for provision. 

I was not able to find anything to release OTP from being used for provisioning using NSIB. 

Regards,
Naeem