概述

　　在智能物联网及先进的传感器迅速发展下，火情实时监测与报警系统也逐渐在楼宇、仓库及室外森林等地方应用。该方案由高精度红外热传感器检测环境的温度，并由低功耗MCU处理后，再由Sub-G或ZigBee传送给监控中心，实现远距离、高精度的火情报警系统。

　　优势

　　• 多达32 x 24点温度检测的非接触式红外热传感器(MLX90640)，数字直接输出温度值，无需再次校准，大大提高检测的准确性;

【MLX90640】

MLX90640红外(IR)传感器阵列结合了高分辨率和在恶劣环境中可靠工作的能力，为更昂贵的高端热像仪提供了高性价比的替代方案。这种32×24像素的器件适用于包括防火系统、智能建筑、智能照明、IP/监控摄像机、HVAC(暖通空调)设备和车辆座椅占用检测在内的安全和便利应用。它具有-40℃至85℃的工作温度范围，可测量-40℃至300℃之间的对象温度。这种高性价比的器件可在其整个测量范围内保持高精度水平，并提供±1℃的典型目标对象温度精度。它还具有出色的噪声性能，在1Hz刷新率下的噪声等效温差(NETD)仅为0.1K RMS。与微测辐射热计的情况不同，该传感器不需要频繁重新校准，从而可确保连续监测并降低系统成本。视场角(FoV)选项包括标准的55°×35°版本和110°×75°的广角版本。MLX90640采用紧凑的、包含必要光学元件的4引脚TO39封装供货。I2C兼容的数字接口可简化集成。

Features and Benefits

Small size, low cost 32x24 pixels IR array

Easy to integrate

Industry standard four lead TO39 package

Factory calibrated

I2C compatible digital interface

Programmable frame rate 0,5Hz…32Hz

3V supply voltage

2 FOV options – 55°x35° and 110°x75°

Operating temperature -40°C ÷ 85°C

Target temperature -40°C ÷ 300°C

Complies with RoHS regulations

2. Application Examples

Temperature sensing in residential,industrial and commercial air conditioning

Home appliances with temperature control

Thermal Comfort sensor in automotive Air Conditioning control systems

Passenger detection and classification

Microwave ovens

Industrial temperature control

Identifying thermal leaks in homes

Security / safety gates

Presence detection / Person localization

3. Description

The MLX90640 is a fully calibrated 32x24 pixels IR array in an industry standard 4-lead TO39 package with digital interface

The MLX90640 contains 768 FIR pixels. An ambient sensor is integrated to measure the ambient temperature of the chip and supply sensor to measure the VDD. The outputs of all

sensors IR, Ta and VDD are stored in internal RAM and are accessible through I2C.

　　• 集成了ARM Cortex-M4强大内核、输出功率高达19.5dBm的专有协议SoC(EFR32MG)，支持ZIGBEE/THREAD/蓝牙/SUB-G多钟不同无线协议，实现火情报警器强大的无线通信功能。

【EFR32MG】

EFR32MG 2.4 GHz 19.5 dBm Radio Board BRD4151A Reference Manual

The EFR32MG family of Wireless SoCs deliver a high performance, low energy wireless solution integrated into a small form factor package.

By combining a high performance 2.4 GHz RF transceiver with an energy efficient 32-bitMCU, the family provides designers the ultimate in flexibility with a family of pin-compatible devices that scale from 128/256 kB of flash and 16/32 kB of RAM. The ultra-low power operating modes and fast wake-up times of the Silicon Labs energy friendly 32- bit MCUs, combined with the low transmit and receive power consumption of the 2.4 GHz radio, result in a solution optimized for battery powered applications.

To develop and/or evaluate the EFR32 Mighty Gecko, the EFR32MG Radio Board can be connected to the Wireless Starter Kit Mainboard to get access to display, buttons and additional features from Expansion Boards.

RADIO BOARD FEATURES

• Wireless SoC:EFR32MG1P232F256GM48

• CPU core: ARM Cortex-M4 with FPU

• Flash memory: 256 kB

• RAM: 32 kB

• Operation frequency: 2.4 GHz

• Transmit power: 19.5 dBm

• Integrated PCB antenna, UFL connector(optional).

• Crystals for LFXO and HFXO: 32.768 kHzand 38.4 MHz.

1. Introduction

The EFR32 Mighty Gecko Radio Boards provide a development platform (together with the Wireless Starter Kit Mainboard) for theSilicon Labs EFR32 Mighty Gecko Wireless System on Chips and serve as reference designs for the matching network of the RF interface.

The BRD4151A Radio Board is designed to operate in the 2400-2483.5 MHz band with the RF matching network optimized to operatewith 19.5 dBm output power.

To develop and/or evaluate the EFR32 Mighty Gecko, the BRD4151A Radio Board can be connected to the Wireless Starter Kit Mainboardto get access to display, buttons and additional features from Expansion Boards and also to evaluate the performance of the RFinterface.

2. Radio Board Connector

2.1 Introduction

The board-to-board connector scheme allows access to all EFR32MG1 GPIO pins as well as the RESETn signal. For more information on the functions of the available pin functions, see the EFR32MG1 data sheet.

2.2 Radio Board Connector Pin Associations

The figure below shows the pin mapping on the connector to the radio pins and their function on the Wireless Starter Kit Mainboard.

3. Radio Board Block Summary

3.1 Introduction

This section gives a short introduction to the blocks of the BRD4151A Radio Board.

3.2 Radio Board Block Diagram

The block diagram of the EFR32MG Radio Board is shown in the figure below.

3.3 Radio Board Block Description

3.3.1 Wireless MCU

The BRD4151A EFR32 Mighty Gecko Radio Board incorporates an EFR32MG1P232F256GM48 Wireless System on Chip featuring32-bit Cortex-M4 with FPU core, 256 kB of flash memory and 32 kB of RAM and a 2.4 GHz band transceiver with output power up to19.5 dBm. For additional information on the EFR32MG1P232F256GM48, refer to the EFR32MG1 Data Sheet.

3.3.2 LF Crystal Oscillator (LFXO)

The BRD4151A Radio Board has a 32.768 kHz crystal mounted.

3.3.3 HF Crystal Oscillator (HFXO)

The BRD4151A Radio Board has a 38.4 MHz crystal mounted.

3.3.4 Matching Network for 2.4 GHz

The BRD4151A Radio Board incorporates a 2.4 GHz matching network which connects the 2.4 GHz TRX pin of the EFR32MG1 to the one on-board printed Inverted-F antenna. The component values were optimized for the 2.4 GHz band RF performace and current consumptionwith 19.5 dBm output power.

For detailed description of the matching network, see Chapter 4.2.1 Description of the 2.4 GHz RF Matching.

3.3.5 Inverted-F Antenna

The BRD4151A Radio Board includes a printed Inverted-F antenna (IFA) tuned to have close to 50 Ohm impedance at the 2.4 GHzband.

For detailed description of the antenna see Chapter 4.5 Inverted-F Antenna.

3.3.6 UFL Connector

To be able to perform conducted measurements, Silicon Labs added an UFL connector to the Radio Board. The connector allows anexternal 50 Ohm cable or antenna to be connected during design verification or testing.Note: By default the output of the matching network is connected to the printed Inverted-F antenna by a series component. It can beconnected to the UFL connector as well through a series 0 Ohm resistor which is not mounted by default. For conducted measurementsthrough the UFL connector the series component to the antenna should be removed and the 0 Ohm resistor should be mounted (seeChapter 4.2 Schematic of the RF Matching Network for further details).

3.3.7 Radio Board Connectors

Two dual-row, 0.05” pitch polarized connectors make up the EFR32MG Radio Board interface to the Wireless Starter Kit Mainboard.

For more information on the pin mapping between the EFR32MG1P232F256GM48 and the Radio Board Connector, refer to Chapter 2.2 Radio Board Connector Pin Associations.

      【火情报警器】

　　在现代城市家庭里，许多人因不懂家庭安全常识引起火灾事故，使好端端的幸福家庭转眼间毁于一旦,有的导致家破人亡,而且一旦发生居民家庭火灾,处置不当、报警迟缓,是造成人员所以说,人们应该积极了解家庭火灾的主要起因,掌握防止发生火灾的知识和万一发生火灾时保护自己的方法,及时消除

　　英国每年发生50000起以上的严重家庭火灾，其中大部分火灾造成人员伤亡和重大的家庭财产损失，有的还连累左邻右舍，火灾损失更加惨重。在调查火灾起因的时候，绝大多数发生火灾家庭的当事人说，以前总觉得火灾是人家的事情，与自己离得很远，没有想到这一次竟然会发生在自己的头上。

　　家庭火灾的主要原因是麻痹大意，没有及时采取预防措施。

　　在我国的一些大中城市，几乎每天都发生家庭火灾，所以防火是每个家庭必须时刻注意的问题。假如能根据您家的实际情况预先采取简单的防火措施，一些悲剧是完全可以避免的。

　　消防部门的统计显示，在所有的火灾比例中，家庭火灾已经占到了全国火灾的30%左右。家庭起火的原因林林种种，可能在我们注意得到的地方，也可能就隐藏在我们根本就注意不到的地方。

　　随着现代家庭用火、用电量的增加，家庭火灾发生的频率越来越高。家庭火灾一旦发生，很容易出现扑救不及时、灭火器材缺乏及在场人惊慌失措、逃生迟缓等不利因素，最终导致重大生命财产损失。探讨家庭火灾的特点及防火对策，对于预防家庭火灾，减少火灾损失具有现实意义。