Thingy:91 X with external SPI Slave possible?

[puz_md]

Hello, I just had a look at the Thingy:91 X with the nRF9151 and nRF5340 SoC's including nRF7002 Wifi support.

My understanding is that the nRF5340 is the main MCU running the main application, while the nRF9151 is used as a Cellular modem

(1) How is communication implemented between the nRF5340 and nRF9151? I noticed that the schematic defines two UART connections between the SoC's, VCOM0 and VCOM1. Are full Cellular modem features on the nRF5340 available through these communication channels? Further, are both channels needed or can one channel be used for a project-specific communication protocol?

(2) Is my assumption correct that even when using the Thingy:91 X with full features (Cellular, Wifi and Bluetooth active), the nRF5340's "GPIO" pins connected to P9 and the nRF9151's "TRACE" pins, are fully available for project-specific extensions? E.g. adding a MCP2515 CAN controller? In other words, these four pins are NOT needed for communication between the nRF5340 and the nRF9151?

Best regards,
Michael

[Michal]

(1) How is communication implemented between the nRF5340 and nRF9151? I noticed that the schematic defines two UART connections between the SoC's, VCOM0 and VCOM1. Are full Cellular modem features on the nRF5340 available through these communication channels? Further, are both channels needed or can one channel be used for a project-specific communication protocol?

It should be using UART with the connectivity bridge application running on nRF5340. One of the channels is used for modem trace by default I think.

(2) Is my assumption correct that even when using the Thingy:91 X with full features (Cellular, Wifi and Bluetooth active), the nRF5340's "GPIO" pins connected to P9 and the nRF9151's "TRACE" pins, are fully available for project-specific extensions? E.g. adding a MCP2515 CAN controller? In other words, these four pins are NOT needed for communication between the nRF5340 and the nRF9151?

Are those the pins used for modem trace by default? Could you show me for example a screenshot?

Best regards,

Michal

[puz_md]

Michal said:

It should be using UART with the connectivity bridge application running on nRF5340. One of the channels is used for modem trace by default I think.

So, one channel is used for communication/operation, and the other is used for modem trace, which is some debug logging? Can the modem trace channel be deactivated, leaving the connection available for project-specific communication?

Further, can the connectivity bridge be combined with project-specific code?

These are the pins I would like to use for an external SPI device:

And these are the VCOM / UART connections between the SoC's:

Best regards,
Michael

[Maria Gilje]

Hi Michael,

puz_md said:

So, one channel is used for communication/operation, and the other is used for modem trace, which is some debug logging?

If you're asking what the modem trace is, the answer is that it is the logs from the cellular modem. See this documentation for more info.

My apologies if I misunderstood your question.

puz_md said:

Can the modem trace channel be deactivated, leaving the connection available for project-specific communication?

I haven't found an answer to this yet.

puz_md said:

Further, can the connectivity bridge be combined with project-specific code?

Yes.

Best regards,

Maria

[puz_md]

Hi Maria,

thanks for looking so deeply into my inquiry!

And please don't forget my main question, which is whether the pins mentioned above are freely available (to connect a SPI CAN controller) in the intended nRF5340+nRF9151 setup.

Best regards,
Michael

[Maria Gilje]

Hi Michael,

puz_md said:

And please don't forget my main question, which is whether the pins mentioned above are freely available (to connect a SPI CAN controller) in the intended nRF5340+nRF9151 setup.

Thank you for the reminder!

I eventually found the correct documentation which clearly states that the P9 connector can be used to connect external boards:

So you should be able to connect an SPI device to the TRACE pins of the P9 connector.

Best regards,

Maria

[puz_md]

Hi Maria,

thanks for looking this up. Although the documentation only mentions a connection to the nRF9151, this should also work with the nRF5340.

By the way, one signal of the connector (P0.12/TRACECLK) is only connected to the nRF9151. If you have contact to the hardware team, could you suggest connecting this signal also to the nRF5340 if there ever is a newer hardware revision? There are still unused pins on the nRF5340 and the fifth signal would be perfect as an interrupt line complementing the SPI interface.

I think this information is enough for initial planning of our project. If you happen to find any more information about disabling the modem traces and using one of the UART connections for project-specific communication, or any other way for communication between the SoC's without using the TRACE pins, just re-open the ticket and add one more comment.

Best regards,
Michael