nRF91 Production Test Image necessary during manufacturing or design verification?

[droberson]

To preface:

Board: nRF9151 custom board
nRF Connect SDK / Toolchain: 3.1.0

Hello,

We just received our first article boards for a design that uses a nRF9151 module. To my surprise, I couldn't send AT+CMEE=1 to the modem until after programming firmware 2.0.2 into the modem core. After some research, I see that all nRF91 modules come preloaded with a Production Test Image (PTI). I see that the PTI firmware allows you to perform the following provisioning steps per the AT command document:

1. Program IMEI
2. Change the power setting

In addition, the PTI firmware lets you drive the transmitter in specific ways which can be used for antenna tuning, certification, etc.

Question 1. For a new board design verification, is there some list of "best practices" that Nordic recommends performing using the PTI firmware, or is the use of the PTI firmware optional if using the pre-programmed IMEI and power class?

Question 2: For mass production of a device, does the PTI firmware need to be run on each board manufactured? If so, why? Assume that we will use the preloaded IMEI and default power class of 3.

Question 3: If we don't need to run the PTI firmware, is there a way to obtain nRF9151 modules pre-programmed with firmware 2.0.2 instead of PTI?

Question 4: The regular AT command document (nrf91x1_cellular_at_commands_v1.3.pdf) states the following under section 5.36 Modem domain event notification %MDMEV:

"Mandatory power class setting (%POWERCLASS) has not been executed with the PTI firmware:" - nRF9151

Is setting the power class really mandatory? I thought it defaulted to power class 3.

Thanks,

Derek

[Michal]

Hello Derek,

Question 1. For a new board design verification, is there some list of "best practices" that Nordic recommends performing using the PTI firmware, or is the use of the PTI firmware optional if using the pre-programmed IMEI and power class?

We are currently working on a version of that document for nRF9151, but you can probably start with our nRF9160 Hardware Verification Guidelines.

Question 2: For mass production of a device, does the PTI firmware need to be run on each board manufactured? If so, why? Assume that we will use the preloaded IMEI and default power class of 3.

I don't think so.

Question 3: If we don't need to run the PTI firmware, is there a way to obtain nRF9151 modules pre-programmed with firmware 2.0.2 instead of PTI?

Please direct that question to your Regional Sales Manager. If you wish so, I can also ask them to contact you as well.

Question 4: The regular AT command document (nrf91x1_cellular_at_commands_v1.3.pdf) states the following under section 5.36 Modem domain event notification %MDMEV:

"Mandatory power class setting (%POWERCLASS) has not been executed with the PTI firmware:" - nRF9151

Is setting the power class really mandatory? I thought it defaulted to power class 3.

Did you get that information on the actual device, or just from the documentation? It should default to power class 3 to my knowledge.

Best regards,

Michal

[droberson]

Hey Michal,

Sorry for the delayed response, I was out of the office. Thanks for the information.

Michal said:

Did you get that information on the actual device, or just from the documentation? It should default to power class 3 to my knowledge.

I got it from here:

https://docs-be.nordicsemi.com/bundle/ref_at_commands_nrf91x1/attach/nrf91x1_cellular_at_commands_v1.3.pdf?_LANG=enus

Section: 5.36 Modem domain event notification %MDMEV

"Mandatory power class setting (%POWERCLASS) has not been executed with the PTI firmware: nRF9151"

The wording makes me think that the POWERCLASS setting must be set for nRF9151. We just got our custom board working on the cellular network, so I am going to assume this is not the case and using the default setting is fine. No biggie.

In summary, it's just a tad confusing.

To summarize your other responses, it sounds like we don't need to run the PTI firmware for the nRF9151, I realize that it is still needed for other module variants (Like the nRF9161 or nRF9131), for anyone else that comes across this thread with a different module.

Michal said:

Please direct that question to your Regional Sales Manager. If you wish so, I can also ask them to contact you as well.

Will do, I have our regional sales contact and will reach out. Since we need to program the app core anyway, I will discuss with our customer if they are OK with programming the modem core firmware as well, resulting in a slightly increased manufacturing build time per board.

Thanks,

Derek