ble-lte gateway support for thingy91X

[kolovoz]

Hi, 

I have been working on a BLE-LTE gateway for Thingy91x for quite some time. To this end, I have tried various options: 

- First, using multi-image builds: modifying the Cellular: LTE Sensor Gateway example, 

and adapting it to Thingy91x. I tried different BLE part samples: “Bluetooth: Peripheral UART,” “Bluetooth: HCI UART,” “Bluetooth: HCI low power UART,” or "Bluetooth: HCI IPC." The main problem here was nRF5340, which has 2 cores (APP and NET), in contrast to the single-core nRF52840. 

Problems I encountered: 

• hci_lpuart – couldn't build the project, missing dependencies for Thingy91x. 
• hci_uart – project built and ran, but I got this error on 5340: bt_hci_core: HCI driver open failed (-1). 
• hci_ipc – tried to use SB_CONFIG_NETCORE_HCI_IPC, but it didn't work: SB_CONFIG_NETCORE_HCI_IPC was assigned the value y, but got the value n. Missing dependencies: SUPPORT_NETCORE_HCI_IPC && <choice NETCORE>. 

- Using sysbuild to integrate “Cellular: nRF Cloud MQTT device message” with ready images: 

SB_CONFIG_NETCORE_HCI_IPC or SB_CONFIG_NETCORE_RPC_HOST. 

Problems: I couldn't make these images work for Thingy91x (platform was not supported). They worked only for nRF53. I also tried creating my own separate apps with sysbuild.cmake ExternalZephyrProject_Add commands for nrf5340/cpunet and nrf5340/cpuapp, but that also failed for me: different Kconfig and dependency problems. 

After trying all these options and more, I feel like making this BLE-LTE gateway on this device is impossible. I saw that the "Cellular: LTE Sensor Gateway" sample is deprecated and only valid for nRF9160 DK, with possible adaptation for Thingy91 (https://devzone.nordicsemi.com/f/nordic-q-a/54848/thingy91-lte-ble-gateway-with-modem-info), but what about Thingy91x? 

Additionally, today I saw this project: https://github.com/nRFCloud/lte-gateway.. And despite .conf and .overlay for Thingy91x, the README file points only to nRF9160-based boards as required. Can I somehow build an LTE-BLE gateway for Thingy91x from that project? 

Summing up, I have a couple of questions: 

1. Is it possible to create an LTE-BLE gateway for Thingy91x, or maybe there are some hardware limitations for that? 
2. If 1 is true, what is the best way to do that? 

 
Thank you for your help.  

[Øyvind]

Hello, 

embeddedCoder said:

In case you haven't seen it, this might be a useful starting point? https://docs.nordicsemi.com/bundle/ncs-3.0.2/page/nrf/applications/connectivity_bridge/README.html 

The Connectivity Bridge is an application that demonstrates the bridge functionality for the Thingy:91 and Thingy:91 X hardware, between the nRF91-series device and the nRF52840 and nRF5340. It acts as a USB composite device, exposing two UART interfaces to a USB host as two CDC ACM devices. It is not an LTE BLE Gateway,

Is it possible to create an LTE-BLE gateway for Thingy91x, or maybe there are some hardware limitations for that? 

This is an interesting use case, and while we don’t currently have a ready-made solution, the hardware platform itself is well-suited for a bridge implementation. All the necessary components are in place, making it a viable foundation. Unfortunately this has not been a priority from our developers.

If 1 is true, what is the best way to do that? 

One plausible solution is to use the Serial Modem shell sample running on the nRF5340 (building sample for thingy91x/nrf5340/cpuapp, and have Serial Modem running on the nRF9151 (connecting with an external MCU). 

Kind regards,
Øyvind

[kolovoz]

Hi Øyvind,
Thank you for your response. I’ll try to implement the solution you recommended and follow up with the results, including any issues I encounter.