Wi-Fi Fundamentals

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nRF70 Series

The nRF70 Series is a Wi-Fi 6 based companion Integrated Circuit (IC), designed to enable the integration of Wi-Fi 6 connectivity into a variety of applications. The series is designed to operate alongside Nordic’s existing nRF52 and nRF53 Series Bluetooth LE and nRF91 Series cellular IoT devices. In addition, the nRF70 Series can also be used with non-Nordic host devices.

Our portfolio consists of the nRF7002, nRF7001 and nRF7000 IC, which have the same core Wi-Fi 6 features but a bit different in functionality and intended use-cases.

Overview of nRF70 Series

nRF7002

The nRF7002 is the first device in our portfolio of unique Wi-Fi products and provides all the features the nRF70 Series has to offer.

nRF7001

With it’s single-band 2.4 GHz radio, the nRF7001 IC is intended for customers who don’t need dual band functionality.

It has all the same main features as the nRF7002 IC.

nRF7000

The nRF7000 IC is designed explicitly for SSID-based Wi-Fi locationing. It enables active and passive scanning of Wi-Fi networks to acquire the SSID’s of nearby AP’s for locationing purposes.

Communication stack

The nRF70 Series implements the Physical (PHY) and Medium Access Controller (MAC) layers of the Wi-Fi stack while the higher layers of the networking stack run on a host device. The host MCU runs the Wi-Fi driver and interfaces with the Wi-Fi chip via SPI/QSPI as shown in the figure below:

Architecture of nRF70 Series and host MCU

The nRF Connect SDK, which is based on the Zephyr RTOS, offers a rich set of tools and libraries for developing Wi-Fi applications. For instance, you can use TCP or UDP sockets, or you can add additional overhead but also get the benefits by using application protocols like CoAP, LwM2M, MQTT or HTTP.

Development hardware

For development, Nordic offers the nRF7002 Development Kit (DK), nRF7002 Evaluation Kit (EK), and nRF7002 Expansion Board (EB). Although we only offer development hardware featuring the nRF7002, the nRF Connect SDK allows you to emulate the other nRF70 Series ICs, by building your application for a different board name and shield.

Note

This course supports going through the hands-on exercises with the nRF7002 DK or the nRF7002 EK with an nRF5340 DK.

nRF7002 DK

nRF7002 DK

The nRF7002 DK combines the Wi-Fi 6 capabilities of the nRF7002 companion IC with the multi-protocol capabilities of the nRF5340 System on Chip (SoC), like Bluetooth LE, Bluetooth mesh, NFC, Matter, Thread, Zigbee, etc. The DK provides everything needed to start developing low-power Wi-Fi applications.

HardwareBoard nameExtra CMake arguments
nRF7002 DKnrf7002dk_nrf5340_cpuapp N/A
nRF7002 DK emulating nRF7001nrf7002dk_nrf7001_nrf5340_cpuappN/A

nRF7002 EK

nRF7002 EK

The nRF7002 EK comes in the form of an Arduino shield and is designed to complement the nRF52840 DK, nRF5340 DK, and nRF9160 DK.

Due to limited memory when running the Wi-Fi stack, this course only supports using the nRF7002 EK together with the nRF5340 DK.

HardwareBoard nameExtra CMake arguments
nRF5340 DK with nRF7002 EKnrf5340dk_nrf5340_cpuapp-DSHIELD=nrf7002ek
nRF5340 DK with nRF7002 EK emulating nRF7000nrf5340dk_nrf5340_cpuapp-DSHIELD=nrf7002ek_nrf7000
nRF5340 DK with nRF7002 EK emulating nRF7001nrf5340dk_nrf5340_cpuapp-DSHIELD=nrf7002ek_nrf7001

nRF7002 EB

nRF7002 EB
Thingy:53 with nRF7002 EB

The nRF7002 EB is a plug-in board, intended for adding Wi-Fi 6 connectivity to the Nordic Thingy:53.

HardwareBoard nameExtra CMake arguments
Thingy:53 with nRF7002 EBthingy53_nrf5340_cpuapp-DSHIELD=nrf7002eb

This course does not support the nRF7002 EB.

Secure or non-secure domain

Since the nRF70 series is a companion IC operating alongside the dual-core nRF5340 SoC, you have the option to build for the secure or the non-secure domain (by adding the suffix _ns to the board name). When building for a non-secure build target, the build will produce two separate environments: a secure processing environment and a non-secure processing environment. The two separate images are the application firmware, running in the non-secure processing environment, and the Trusted Firmware-M (TF-M), running in the secure processing environment.

Radio coexistence

Importance of radio coexistence

Since Wi-Fi shares unlicensed radio bands with other technologies, such as Bluetooth, radio coexistence becomes an important aspect. This is especially important for the nRF70 Series as it is often implemented alongside Bluetooth Low Energy in the same device. These two technologies using the same radio band can cause signal quality degradation on both radios and mutual interference. Therefore, correct coexistence mechanisms ensure minimal interference between the various radio technologies sharing the same radio bands.

The nRF70 Series follows the IEEE recommendations for radio coexistence and builds on top of it with proprietary algorithms, creating a centralized logic that prioritizes transmission requests between Wi-Fi and Bluetooth Low Energy and ensures fair resource allocation.

Coexistence interface in the nRF70 series

The coexistence function in the nRF70 is based on the IEEE-defined Packet Traffic Arbitration (PTA) module, connected to configurable coexistence hardware logic functions that facilitate radio-usage prioritization and resource allocation.

Radio coexistence can also be an important factor for regulatory RF certification. By utilizing the coexistence interface, you make sure that two radio transmitters are not running at the same time in a frequency band, simplifying the number of measurement combinations required during certification.

Two main sets of hardware configurations can be used; the first is concerned with the interface hardware configuration, and the second is concerned with the antenna configuration.

Hardware configuration

Hardware configurations for coexistence interface

As seen in the figure, there are three different hardware configurations for the interface. The PTA module logic sits beside the Wi-Fi logic, and the secondary technology (such as Bluetooth Low Energy) would have to request transmissions. In the 3-wire without priority signal configuration, the secondary technology would have to request transmissions and the PTA module can respond back with permission granted. This mode is supported in the nRF70 series in both hardware and firmware. However, this same 3-wire configuration could also include a priority signal multiplexed in the Tx/RX line, so enable the secondary technology to request priority. Lastly, a 4-wire configuration can also be used where the priority line is separate from the TX/RX line. The latter two configurations are only supported through hardware at the moment and not yet supported in firmware as per the latest nRF Connect SDK release.

Antenna configuration

Antenna configuration also plays an important role in the operation of the coexistence interface. Two antenna modes are available: shared antenna mode and separate antenna mode.

In the shared antenna mode, the PTA makes priority decisions and controls the switch between Wi-Fi and the secondary technology. Only one radio technology is connected to the antenna at any time.

In the separate antenna mode, each technology is permanently connected to its own antenna.

The nRF Connect SDK has the Wi-Fi Bluetooth LE coexistence sample for more information about configuring an application with coexistence.

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