Our portfolio consists of the nRF9151 SiP, and its predecessor, the nRF9160 SiP.
The nRF91 Series is Nordic cellular IoT based System-in-Package (SiP) supporting both LTE-M and NB-IoT and is the hardware used throughout this course. The nRF91 Series SiP consists of an application processor, an LTE modem, an RF Front End (RFFE), a PMIC, passive components, and crystal oscillators. In addition, you need a power source (typically a battery), an (e)SIM, and an LTE antenna. You can also add a dedicated GPS antenna and sensors.
For an exhaustive list of all the nRF91 Series features, see the Product Specification:
- For the nRF9151 SiP, see the nRF9151 Product Specification.
- For the nRF9160 SiP, see the nRF9160 Product Specification v2.1.
Nordic Semiconductor provides modem firmware binaries to operate the LTE modem, and the nRF Connect SDK as a tool to develop the application, which will run on the application core and interface with the modem.
This course will focus mainly on application development for the application core and how to interface with the LTE modem using the available libraries in the nRF Connect SDK.
nRF91 Series SiP architecture
The application processor runs your application, while the modem runs modem firmware, provided by Nordic as pre-compiled binaries. The nRF Connect SDK contains the Modem library, which the application uses to interface with the LTE modem.
The application processor on the nRF91 Series SiP is an Arm Cortex-M33 MCU with Arm TrustZone technology. This is relevant because the TrustZone technology enables the separation of a secure and non-secure domain.
At boot-up, the application always starts execution from the secure domain. From there, the Trusted Firmware-M (TF-M) is started, which will configure part of the memory and peripherals as non-secure and then jump to the main application in the non-secure area.
This is all automated by the nRF Connect SDK when building your application with TF-M. As you can see from the figure, the modem library, which interfaces with the LTE modem, is defined in the non-secure domain. Therefore, when building for the nRF91 Series, you should always build with TF-M, i.e with the _ns suffix.
Communication stack
Below is an illustration of the nRF91 Series SiP communication stack. Throughout this course, we will cover different layers and refer back to this diagram. The modem firmware is running on the modem core of the nRF91 Series SiP and is provided as a binary. To interface with the modem, we have the Modem Library. On top of there sits all the drivers, subsystems and libraries available in the nRF Connect SDK and at the top is your cellular application.
- Lesson 2: AT commands library and the LTE link controller library.
- Lesson 3: Modem library and the layers TCP / UDP and TLS / DTLS.
- Lesson 4: TCP and TLS, and the MQTT library, an implementation of the TCP-based application layer protocol MQTT.
- Lesson 5: UDP and DTLS, and the CoAP library, an implementation of the UDP-based transport protocol CoAP.
- Lesson 6: GPS, and how to interface with it using the GNSS Interface in the Modem Library (not pictured here).
Multi-image build
In nRF Connect SDK Fundamentals, we briefly discussed the concept of Sysbuild. With cellular IoT development, Sysbuild becomes more relevant because you are developing on the nRF91 Series SiP, which is a multi-partition target with a secure and a non-secure domain. Any application that wants to interface with the modem needs to run in the non-secure domain. Even though this happens automatically when building for the board target with TF-M (_ns suffix), it is useful to be aware that it happens.
All nRF91 Series applications require Trusted Firmware-M to be included in the build.
Note
When using Sysbuild, the resulting executable can be found at <build_directory>/merged.hex.
Development hardware
For development, Nordic offers the nRF9151 Development Kit (DK), nRF9160 DK, and the Thingy:91 Prototyping Platform, all of which are supported by this course.
nRF9151 DK
The nRF9151 DK is an affordable, pre-certified single-board development kit for evaluation and development on the nRF9151 SiP for LTE-M, NB-IoT, GNSS, and DECT NR+.
| Hardware | Board target |
| nRF9151 DK | nrf9151dk/nrf9151/ns |
Thingy:91 X
The Thingy:91 X is a multi-sensor cellular IoT prototyping platformhouses the nRF9151 SiP for the development of LTE-M, NB-IoT, DECT NR+ and GNSS, as well as the nRF5340 SoC and the nRF7002 companion IC.
See the table below for the board targets to use when building applications for this device.
| Hardware | Board target | Board target (nRF5340) |
| Thingy:91 X | thingy91x/nrf9151/ns | thingy91x/nrf5340/cpuapp/ns |
nRF9160 DK and Thingy:91
The nRF9160 DK and Thingy:91 both house the nRF9160 SiP for the development of LTE-M, NB-IoT, and GNSS. These devices also house an nRF52840 board controller that can be used to build a Bluetooth LE gateway, for instance, the LTE Sensor Gateway sample in nRF Connect SDK.
See the table below for the board targets to use when building applications for these devices.
| Hardware | Board target | Board target (nRF52840) |
| nRF9160 DK | nrf9160dk/nrf9160_ns | nrf9160dk/nrf52840 |
| Thingy:91 | thingy91/nrf9160_ns | thingy91/nrf52840 |
LTE certification
All nRF91 Series SiP’s and the accompanying development hardware have been certified for a broad range of LTE bands globally.
All cellular devices require certification – which the type depends on LTE bands, service provider and operation area. It is often possible to reuse the nRF91 Series SiP’s certification in your own device. See the nRF91 Series certifications page for more information.
Antenna design
When developing a cellular IoT application, antenna design is a critical factor that should be prioritized early in the hardware development process.
For more information on antenna design, check out the following resources
- nRF91 Series Antenna and RF Interface Guidelines – This whitepaper outlines the basic antenna parameters and design factors that impact the antenna and RF performance of your device. It provides recommendations and requirements for the antenna to reach optimal RF performance, and offers examples of RF interface implementations, including different test features and active RF components controlled by the nRF91 Series. It also gives an overview of RF and antenna test items to prepare for when building an IoT device with the nRF91 Series.
- Ignion Virtual Antenna Academy – This is an online self-paced free-of-charge academy provided by Ignion, and their course Introduction to Wireless Components and Virtual Antenna Technology teaches you the basics of wireless components and virtual antenna technology.
