A second function of the onboard nRF52840 System on Chip (SoC) is to act as a Bluetooth® or IEEE 802.15.4 network processor. This makes it possible to develop products that utilize both Long-Term Evolution (LTE) and other RF protocols supported by Nordic on the nRF9160 DK.
Since most of the General-Purpose Input/Output (GPIO)s of the nRF52840 SoC are used for board control (see the schematic below), it is not intended to be a full programming and development target on the nRF9160 DK.
However, if combined with board control firmware, it can run code that requires limited access to GPIO, such as wireless controllers or network processor implementations of Bluetooth and IEEE 802.15.4 protocols from Nordic Semiconductor.
This enables the nRF9160 DK to implement a cellular to Bluetooth (and/or IEEE 802.15.4) bridge or gateway. To enable this, nRF52840 has a 2.4 GHz antenna fitted along with nine GPIOs that can be connected to nRF9160 through the board control routing. For details, see Board control routing.
Firmware examples for such bridge or gateway implementations can be found in nRF9160: LTE Sensor Gateway.
