nRF24LE1及nRF24LU1+的GAZELL跳频协议_gazell协议资源-CSDN文库

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nordic官网的GAZELL协议，支持1主机最大6从机的RF通信协议，主要优点是： 1.低功耗 Gazell协议是低功耗协议，可设计为纽扣电池供电的应用 2.抗干扰性 Gazell协议完成自动跳频及抗干扰的无线通信，具有在复杂环境下优异的抗干扰性能 3.低延时 Gazell协议充分利用nRF高速通信的特性，具有低延时特性，特别满足PC周边及其他应用 4.高安全性 Gazell协议具有AES128bit高强度加密，确保数据传输的安全可靠 5.简单易用 Gazell协议以源代码或库的方式提供，可与nrf24LE1及nrf24LU1P无缝连接，应用极为方便，例如发送数据时用户只需调用发送函数，协议自动完成跳频及抗干扰传输，无需用户干预。 ### nRF24LE1及nRF24LU1+的GAZELL跳频协议详解 #### 一、概述 Nordic Semiconductor推出的GAZELL协议是一种专为nRF24LE1及nRF24LU1+设计的低功耗、抗干扰性强的无线通信协议。该协议支持最多一个主设备与六个从设备之间的通信，适用于多种低功耗应用，如无线键盘、鼠标等。 #### 二、GAZELL协议的主要特点 ##### 1. 低功耗 GAZELL协议通过优化的通信机制和高效的能耗管理实现了极低的功耗水平。这一特性使得基于该协议的设备能够在纽扣电池的供电下长时间运行。 ##### 2. 抗干扰性该协议具备自动跳频功能，能够有效地避免信道间的干扰。在复杂的无线环境中，GAZELL协议依然能保持稳定的通信质量。 ##### 3. 低延时利用nRF24LE1及nRF24LU1+高速通信的能力，GAZELL协议实现了低延时的数据传输，非常适合于对实时性要求较高的应用场合。 ##### 4. 高安全性 GAZELL协议内置了AES128位加密技术，确保了数据传输过程中的安全性和可靠性。 ##### 5. 简单易用该协议以源代码或库的形式提供，并与nRF24LE1及nRF24LU1+无缝集成，大大简化了开发流程。用户只需要调用简单的API即可完成数据的发送和接收操作，无需深入了解底层的通信细节。 #### 三、GAZELL协议的实现原理 GAZELL协议的核心组件包括： 1. **通用代码基础**：GAZELL协议的通用部分采用8051 MCU编写，这部分代码独立于硬件平台。 2. **硬件抽象层（HAL）**：为了确保协议可以在不同的硬件平台上运行，GAZELL采用了硬件抽象层来隔离底层硬件差异。 3. **移植模块**：这些模块负责处理与特定硬件相关的功能，确保GAZELL协议能够在nRF24LE1及nRF24LU1+等特定设备上正常工作。 #### 四、RF协议固件模块根据官方文档，GAZELL协议固件主要包括以下模块： 1. **GAZELL Link Layer (gzll)**：这是针对nRF24L01+射频收发器的链路层实现。该模块定义了网络中的角色分配、协议状态、定时控制等内容。它还支持配置和API接口。 2. **GAZELL Pairing Library (gzp)**：该库提供了动态配对功能，使得两个或多个设备可以安全地建立连接。这在多设备间的安全通信场景中非常重要。 #### 五、GAZELL协议的工作方式每个GAZELL节点都可以配置成与其他最多六个节点进行通信。每个节点既可以作为发送端也可以作为接收端。对于超过七个节点的网络，可以通过设置多个网络来实现。 #### 六、GAZELL协议的实际应用场景 - **无线键盘和鼠标**：得益于GAZELL协议的低功耗特性，无线外设可以在长时间内保持稳定的工作状态。 - **智能家居系统**：GAZELL协议的抗干扰性和低延时特性使其成为智能家居控制系统的理想选择。 - **工业自动化**：对于需要高度可靠性和安全性的工业环境，GAZELL协议提供的AES128位加密保障了数据的安全传输。 GAZELL协议不仅具备出色的性能指标，而且易于集成，非常适合作为低功耗无线通信解决方案的基础。

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RF protocol

[Firmware]

The Gazell protocol has a common code base and porting modules for the supported modules. This

common part of Gazell is written for an 8051 MCU. Apart from this, it is hardware independent.

Hardware dependency is ensured by HAL modules (Hardware Abstraction Layer (HAL)) and the

porting modules. HAL is used for the RF tranceiver, while the porting modules ensure that the special

needs of the protocol not reusable for other projects, are met.

The table below provides an overview of the RF protocol firmware modules available for the nRF24LE1 /

nRF24LU1+ radio MCUs.

Generated on Tue Mar 29 2011 13:46:12 for nRFGo SDK by 1.7.2

Gazell Link Layer (gzll)

[RF protocol]

Link layer for the nRF24L01+ radio.

Contents

Introduction

l Roles in a Gazell star network

Properties of Gazell

l Protocol states

l Protocol timing in Gazell

Pipes and addresses in Gazell

l Configuration

Application Programming Interface (API) for the Gazell Link Layer

Main Page Modules Index

RF Protocol modules Description

Supported

devices

Gazell Link Layer (gzll) Link layer for the nRF24L01+ radio.

nRF24LE1 QFN24

nRF24LE1 QFN32

nRF24LE1 QFN48

nRF24LU1+

Gazell Pairing Library (gzp)

This is a library for adding dynamic pairing

functionality to an application using the

Gazell Link Layer.

nRF24LE1 QFN24

nRF24LE1 QFN32

nRF24LE1 QFN48

nRF24LU1+

Main Page Modules Index

页码，1/64nRFGo SDK: RF protocol

2011-12-23file://C:\Documents and Settings\Administrator\Local Settings\Temp\...

Introduction

Gazell Link Layer is a library with functions for setting up and configuring the link layer of a wireless

desktop or other wireless applications. The Gazell Link Layer replaces the earlier Frequency Agility

Protocol from Nordic Semiconductor. In the rest of this text we will shorten "Gazell Link Layer" to

"Gazell".

Each Gazell node can be configured for communication with up to six other Gazell devices in a network.

Each node can transmit and receive data. Networks with more than seven (1+6) nodes can be set up

to work with Gazell, but no Gazell node in the network can know more than six other nodes.

For the sake of simplicity we will in the rest of the help file assume that we have a star network with

one Host node and one to six Device nodes. With this network it is very easy to write a wireless

application using Gazell, since no network layer will be needed on top of Gazell. Setting up addresses

and channel tables is also very simple for a star network.

Roles in a Gazell star network

In a simple Gazell star network we have two static roles: Host and Device. There will be one Host and

one to six Devices in the network. This is a typical wireless desktop configuration where no role

switching is ever required - there will be a "dongle" that is always a Host, plus a mouse, keyboard and

other input units that are always Devices.

A Host mainly receives data, but can still send data back to a transmitting Device by piggy-backing

data onto the acknowledgement packets returned to that Device.

A Device mainly transmits data, but can still receive data in the acknowledgements returned from the

Host.

It is always a Device that initiates a data transfer. This means that a Host has to wait for a packet from

a Device before it can send anything to the Device. Note that it is still possible to fulfill latency

requirements for Host to Device traffic (like a command from the PC to turn on the caps lock LED on a

keyboard). The application on the Device side will just have to send dummy poll packets at regular

intervals to the Host. The Host will then return any pending data in the following acknowledgement. In

a typical desktop application the Host to Device latency requirement is usually so relaxed that such a

poll will not consume significant power.

Properties of Gazell

Low Power

Gazell is a protocol designed to minimize power consumption. For applications like wireless desktops or

remote controls where the power capability on Host and Device are very different, Gazell will operate in

an asymmetric mode where the Devices draw much less power than the Host.

In this mode the Device is free to send data at its own discretion. A remote control will for instance

only send each time a button is pressed. All "protocol smalltalk" just to maintain a link is thus avoided.

This minimizes power on the Device side at the cost of more power on the Host, since the Host will

have to always listen.

In battery-to-battery operations, where power saving is equally important on both Host and Device

side, Gazell can be set up in a more symmetric mode where both Host and Device have a low duty

cycle. In this case there is a trade-off between latency and power consumption. The longer latency one

can accept, the lower the power consumption will be. This tradeoff can be configured by Gazell.

To minimize power and latency in applications with high report rates, Gazell also has a semi-

synchronized mode. This mode needs an accurate system clock on both sides. This mode does not use

power-wasting synchronization messages to keep Host and Device in sync. Instead the Device uses the

ordinary acknowledgment packets to synchronize its transmission channel time slots with the Host

whenever an ACK is received.

页码，2/64nRFGo SDK: RF protocol

2011-12-23file://C:\Documents and Settings\Administrator\Local Settings\Temp\...

Note that synchronization occurs at the discretion of the Device - the Host does not even know whether

the Device is synchronized or not. This means that some Devices can operate in asynchronous mode at

the same time as other Devices are in synchronous mode.

Gazell does not lose any data when the Host and Device eventually drift out of sync - it merely leads to

more retransmissions until the Device is able to sync up again. As soon as a retransmitted packet is

acknowledged, the Device will use the arrival time of the acknowledgement to adjust its

synchronization. So this is an imprecise sync mechanism where power and latency are saved whenever

the protocol is in sync, but the protocol is still working fine when we happen to be out of sync. We call

it "semi-synchronized mode".

Robust against interference

Gazell can be configured with frequency agility or frequency hopping to avoid interferers. "Frequency

agility" means that the protocol stays on the same frequency channel as long as there is little

interference on that channel. When a channel is quiet it makes little sense to switch to another

channel. The new channel is more likely to have interference than the current channel, so

unconditionally switching channels for each packet would increase the average number of

transmissions and thus the average power consumption and latency.

"Frequency hopping" means that that the protocol changes channel for each packet transmitted. This is

required by some radio regulations to spread the radio power across the spectrum when power

amplifiers are used to increase the range of the radio.

Gazell itself will cause little interference for other 2.4 GHz radios since the protocol does not need to

send packets to maintain a link. Gazell is only active when there is data to send. This also gives little

interference between Devices talking to the same Host. (These Devices have no knowledge of each

other and operate independently of each other.)

The size of the channel table is a trade-off between latency and robustness. Having a large channel

table gives us the option of trying many channels from the 2.4 GHz band to find a quiet channel. But

this means that the Host and Device need more time to find each other and consequently more

transmissions per packet, increasing power consumption and latency.

Gazell has configurable channel tables. Experience has shown us that having three to five channels

spread out in the 2.4 GHz band is a good compromise, giving very low latency and maintaining good

immunity to interference.

Low latency and high report rate

The perceived responsiveness and accuracy of a Device like a wireless mouse depends on the sample

rate and resolution of the optical sensor, but equally on the report rate and latency of the radio

protocol.

Gazell is a simple protocol with little protocol overhead and, combined with 2 Mbits/s data rate of

Nordic Semiconductor radios, we get high report rates.

Gazell achieves low latency by two means: asymmetric duty cycles and semi-synchronization.

Asymmetric duty cycles means that the Host can be configured to always listen while the Device only

has to send whenever there is data. Therefore the Device does not have to wait for the next listening-

slot on the Host before starting a transmission attempt.

The semi-synchronized mode described earlier also helps to achieve low latency, since when we are in

sync the Device will hit the correct channel and channel time-slot at the Host every time.

Simplicity

Using the Gazell protocol is easy. Since the Devices in a Gazell star network do not know about each

other and there is no co-ordination between them, setting up the Devices becomes very simple.

There are no special connection setup packets - all packets are data packets - and Gazell has no need

for packet headers of its own. We do not need send link packets at regular intervals to maintain a link.

页码，3/64nRFGo SDK: RF protocol

2011-12-23file://C:\Documents and Settings\Administrator\Local Settings\Temp\...

Gazell protocol states for a Host

Note that for a star network the Host should only be in the states IDLE and HOST. If a Host application

calls gzll_tx_data() the Host will enter the DEVICE state and switch roles and become a Device. Then

we do not have a star network any more - just a set of unconnected Devices.

Gazell supports two HOST-state modes:

l Mode 0: low latency mode

Mode 1: low power mode

In low latency mode the Host listens continuously. Each channel in the channel table is monitored in a

rotating fashion. This mode is used when the Host has ample power and when low latency for Device to

Host data is important.

In low power mode the Host radio is in POWER DOWN or STANDBY between listening periods. In each

listening period, the Host listens for a short time on one channel. Then the Host goes to sleep for a

while before listening on the next channel. This gives less power consumption on the Host side than for

low latency mode.

In asynchronous mode (see below) a Host in low power mode means more transmission attempts and

thereby longer latencies and more power consumption on the Device side. However, in semi-

synchronous mode the Device will be synchronized to the short listening periods of the Host, so we do

not waste transmit attempts and power at the Device side. (But we will still get increased latency.)

Low power mode is used for battery-powered Hosts and when a Host is in standby mode. It is normal

for a Host to switch between the low power mode and low latency mode. A Host like a USB-dongle for

a wireless mouse will for instance be in low latency mode when the mouse and PC are active, but will

switch to low power mode when the PC is inactive and the USB-dongle enters SUSPEND mode.

DEVICE state

In DEVICE state, the protocol sends data. Gazell enters DEVICE state with the function call

gzll_tx_data(). Gazell handles re-transmission of lost packets and channel changes to avoid

interference. This is transparent to the application.

页码，5/64nRFGo SDK: RF protocol

2011-12-23file://C:\Documents and Settings\Administrator\Local Settings\Temp\...

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评论收藏

内容反馈

zzytyy1023

2012-11-16

很好的资料，谢谢，看得比较吃力
zoudejile

2012-10-30

有助了解而已，实际项目用处不大
老班-智勤

2019-06-03

不确定怎么样，研究研究看了，反正很贵
zhylun

2013-06-24

学习中，希望能有所帮助！
Daveee

2012-08-21

不是很清晰，学习一下

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