News | July 16, 2007

Nordic Reveals Three Hidden Features In Its 2.4 GHz RF Transceiver

Source: Nordic Semiconductor ASA
Oslo, Norway -- Nordic Semiconductor ASA unveiled three hidden features in the Enhanced ShockBurst hardware link layer of its nRF24L01 2.4 GHz transceiver.

The Enhanced ShockBurst hardware link layer has enabled the implementation of ultra low power, high performance communication using low cost host microcontrollers. The new features enable several improvements of power efficiency for bi-directional and uni-directional systems, without adding complexity on the host controller side.

These hidden features are auto acknowledgement with payload, dynamic payload length, and selective auto acknowledgment.

The features have been included and tested in the nRF24L01 from its original release, but have been undocumented until today. As such there have been no changes to the product, and consequently all nRF24L01 transceivers shipped to date have these features.

"We are thrilled to unveil these exciting features," says Thomas Embla Bonnerud, Nordic Semiconductor Product Manager for Standard Components. "With the nRF24L01, Nordic Semiconductor is the market leader in ultra-low power 2.4 GHz communication. This new feature set enables our customers to take their wireless product design to the next level in terms of power efficiency."

On the question of why these features had been hidden and why they are unveiled now, Bonnerud responds: "I am sorry to say that we cannot comment on why these features have been hidden, but the timing of this announcement is hugely relevant to many existing and future customers because we are seeing a lot of emerging applications where the extended functionality of the nRF24L01 will make a huge difference."

"One example is Windows Vista SideShow remote controls. For these types of remote there is a need for a cost efficient RF technology that is capable of a bi-directional link with key presses being sent in one direction and display data being sent in the other. The combination of this new feature set, a high data rate and ultra-low power makes the nRF24L01 the perfect solution."

Auto Acknowledgment with Payload
This feature enables implementation of very efficient bi-directional two-way data link with minimum loading on the host microcontroller.

When using the Enhanced ShockBurst auto-acknowledgment feature it is now possible to include a payload in the automatic acknowledgment packet from the Primary Receiver (PRX) to the Primary Transmitter (PTX). The host controller simply clocks in the payload data into the PRX TX FIFO and the radio will complete the data transmission without further involvement from the host controller.

For a bi-directional data link the main advantages of this feature is lower average power consumption due to less active time for the host controller, plus a faster radio turnaround time and reduced receive cycle. It also enables implementation of advanced power efficient bi-directional protocols on extremely low cost host controllers as the radio itself handles all the time critical processing. Minimizing time on air with faster radio turnaround and shorter receive cycles also reduces the probability of packet collisions, thus improving the overall co-existence performance of the system.

Dynamic Payload Length
This feature enables a more flexible and power efficient system implementation by offering a dynamic payload length. Instead of having a fixed packet length, each individual packet can have a different length, with a payload size ranging from 1 to 32 Bytes. The Enhanced ShockBurst™ base band engine will include and decode the payload length info in the packet.

With this feature, therefore, the packet length does not have to be scaled for the largest payload. Instead each individual packet length is scaled to the size of the actual payload at that time. For applications where there are a variety of payload lengths this can provide significant power savings by minimizing on-air time. Always using the shortest packet size needed reduces the probability of packet collisions, thus improving overall co-existence performance of the system.

Selective Auto Acknowledgment
When using the Enhanced ShockBurst auto-acknowledgment feature designers can select, on a per-packet-basis, whether the PRX primary receiver shall provide an acknowledgment or not. The advantage of this is to again reduce on-air time, thus power consumption, for applications where a subset of the packet transactions does not require guaranteed delivery.

SOURCE: Nordic Semiconductor ASA