when nrf9160 as serial modem, can AT command be send/received over SPI interface without modify FW ?

[ivan.li]

Hi, 

When nrf9160 as serial modem, can AT command be sent/received over SPI interface without modify FW ? 

As I know, the UART interface is the default setting for transmission AT command, but how about SPI interface ? 

thanks & best regards

ivan li

[Øyvind]

Hello, 

The Serial LTE Modem does not support SPI communication by default, this would need to be configured by you. The SLM application runs on the non-secure part of the nRF9160 which then forwards communication to the modem itself. See Features of nRF9160 series for more information. 

Application and modem domains interact through the interprocessor communication (IPC) mechanism. The LTE modem is accessible to users through the modem API. More information can be found in the nRF9160 Product Specification.

Let me know if anything is unclear. 

Kind regards,
Øyvind

[ivan.li]

thanks Øyvind.

in our application, nRF5340 will be the main processer, using SPI interface communicate with nRF9160,  so i am not asking the two cores of nRF9160 communication

for traditional modem, usually use UART as the interface, but here i want to know whether SPI can instead of the UART. 

please confirm if it still can (or can be achieve by changing code or configurations)

thanks & best regards!

Ivan li

[Øyvind]

The communication between the two devices, nRF5340 and nRF9160 can be whatever you want it to be. The communication between the application core and the modem in the nRF9160 will always be through the modem API which needs to be on the non-secure core of the nRF9160.
The main important thing is how to handle unsolicited result code (URC) from the modem. How will the nRF9160 forward these at any time?

Is there a reason for why you want to change UART to SPI? 

Remember that the nRF9160 is not a traditional modem, the nRF9160 is a low-power cellular IoT (Internet of Things) solution, integrating an ARM Cortex-M33 processor with advanced security features, a range of peripherals, as well as a complete LTE modem compliant with 3GPP LTE release 13 Cat-M1 and Cat-NB1, and 3GPP LTE release 14 Cat-NB1 and Cat-NB2 standards.

[ivan.li]

thanks Øyvind for your quickly feedback

1: The main important thing is how to handle unsolicited result code (URC) from the modem. How will the nRF9160 forward these at any time?

Ivan li: it could be any time, you know, when the downlink command/data from cloud to device is unknow, so, once the device is alive, it must forward the URC to nRF5340

Is there a reason for why you want to change UART to SPI? 

Ivan li: I do not support SPI, I want to use UART, but for some reason, HW team want to use the SPI, so I: 1) want to know is it possible 2)  need some evidence to convince HW team, let them change the HW design.

you are more professional than me, so please help me about this. 

thanks & best regards!

Ivan Li

[Øyvind]

ivan.li said:

you are more professional than me, so please help me about this. 

We do not have support SPI in the Serial LTE Modem application. This is something you will need to implement on your side, which means rewriting a lot of code.

Kind regards,
Øyvind

[ivan.li]

thanks, Øyvind

I will suggest HW team change the interface to UART. 

Br, Ivan li

[Øyvind]

No problem, Ivan. Let me know if you need any more support. 

Kind regards,
Øyvind