nRF91x1 SiP LTE firmware pin configuration

[k.leonhardt]

Hi 

I cannot find the pin-configuration for the nRF9251 using the nRF91x1 SiP LTE firmware. I can see that the Thingy91X and the nRF9151-DK board are using different UART pins (for both AT commands and DEBUG port I believe). And Looking on the Serial_LTE_modem example are using a third version.

Is there a documentation for the nRF91x1 SiP LTE firmware besides the AT command documentation? Especially regarding the peripheral design supported by the firmware.

Does it run directly on the nRF9151-DK board? Which pins on nRF9151 are used for the AT command UART?

Regards

Kasper

[Øyvind]

Hello Kasper, 

I'm not sure I understand your question. Are you referring to how the Application core of the nRF91x1 communicates with the LTE modem?

The application communicates with the modem itself via the interprocessor communication (IPC) mechanism, have a look at the LTE Modem chapter in the nRF9151 datasheet.

Have a further look at our Developer Academy - Cellular IoT Fundamentals to get to know our product better.

If my answer does not provide any clear answer to your question, please elaborate more on what you are trying to achieve.

Kind regards,
Øyvind

[k.leonhardt]

I was not precise enough.

I will start to describe out application:

We are going to build a custom board with an application MCU and the nRF9151 SiP. To avoid building firmware for both targets, we want to flash the nRF9151 SiP with the pre-compiled image found in mfw_nrf91x1_2.0.2.zip. This image should as far as I understand let the nRF9151 SiP work like most other cellular modems on the market. All of these modems are controlled from the application MCU by using AT commands sent trough an UART between the application MCU and the nRF9151 SiP. I believe that we agree so far. En example is the command "AT+CGMI" which should return the string "Nordic Semiconductor ASA" and "OK".

And then the HW design for our application:

When we design the custom board holding application MCU and the nRF9151 SiP we need to connect the UARTS between these two controllers. On our application MCU we can choose what ever UART is available, but I believe that the precompiled nRF91x1 SiP LTE firmware image found for download on the product page for nRF9151 SiP.

So here are the questions again:

1. Does the nRF91x1 SiP LTE firmware image programmed to the nRF9151 makes it usable like other cellular modems on the market, controlled using AT commands?
2. If yes to 1: Does the document nrf91x1_cellular_at_commands_v1.3.pdf describe this protocol on this interface?
3. If yes to 2: Which pins on the nRF9151 SiP using the nRF91x1 SiP LTE firmware image are used for UART communication? I believe that there is one UART allocated for AT commands and one for debug/trace.
4. And where do I find the full documentation of the "nRF91x1 SiP LTE firmware image" besides the document describing the AT commands. I believe that there is a lot of pins in the nRF9151 SiP that can be used for different stuff besides the UART's. E.g. some GPIO's controllable by using AT commands.
   
   

Does this 

[Øyvind]

Hi, and thanks for elaborating a little more. 

k.leonhardt said:

To avoid building firmware for both targets, we want to flash the nRF9151 SiP with the pre-compiled image found in mfw_nrf91x1_2.0.2.zip.

Yes, the modem FW is a FW package delivered by us, and is not supposed to be edited or built by customers. This modem FW is built with support for 3GPP LTE release 14 LTE-M and NB-IoT standards, selected optional 3GPP LTE release 14 and 15 features, GPS L1C/A and QZSS L1C/A positioning, and the modem acts as a black box. 

k.leonhardt said:

Does the nRF91x1 SiP LTE firmware image programmed to the nRF9151 makes it usable like other cellular modems on the market, controlled using AT commands?

Yes, but only for LTE-M and NB-IoT. There is no support for GSM/4G/5G.

k.leonhardt said:

If yes to 1: Does the document nrf91x1_cellular_at_commands_v1.3.pdf describe this protocol on this interface?

Yes, modem FW v2.0.2 release is aligned with v1.2 of the nRF91x1 Cellular AT Commands Reference Guide.

k.leonhardt said:

If yes to 2: Which pins on the nRF9151 SiP using the nRF91x1 SiP LTE firmware image are used for UART communication? I believe that there is one UART allocated for AT commands and one for debug/trace.

If you are running an application such as e.g. AWS IoT Core sample from the nRF9151, there is no need for UART. If you want the nRF9151 to act as a stand alone modem similar to what other devices do, then the Serial LTE Modem application is your go-to FW. The latter also includes some propriatery AT commands to control the application core of the nRF9151. 

k.leonhardt said:

And where do I find the full documentation of the "nRF91x1 SiP LTE firmware image" besides the document describing the AT commands. I believe that there is a lot of pins in the nRF9151 SiP that can be used for different stuff besides the UART's. E.g. some GPIO's controllable by using AT commands.

For the LTE firmware image, you could look at the release notes. All other documentation is found under docs.nordicsemi.com, both for our nRF Connect SDK and the nRF9151 SiP.

Kind regards,
Øyvind