Microchip公司的MRF24WB0MA和MRF24WB0MB是低功耗2.4 GHz, IEEE Std. 802.11兼容的表面安装的RF收发器模块,包括了所有的RF元件:晶振,旁路和偏压无源元件以及MAC,基带,RF和功率放大器,内置的硬件支持 AES和TKIP (WEP, WPA, WPA2 安全),数据速率为1和2 Mbps,通信范围达400米,主要用于智能电网,消费类电子,工业控制和遥控设备.本文介绍了MRF24WB0MA/B主要特性,方框图,应用电路图以及Wi-Fi演示板主要特性,电路图和主要元件布局图.
The MRF24WB0MA and MRF24WB0MB are low-power, 2.4 GHz, IEEE Std. 802.11-compliant, surface mount modules with all associated RF components – crystal oscillator, bypass and bias passives with integrated MAC, baseband, RF and power amplifier, and built-in hardware support for AES, and TKIP (WEP, WPA, WPA2 security).
The integrated module design frees the designer from RF and antenna design tasks and regulatory compliance testing, ultimately providing quicker time to market. The MRF24WB0MA module is approved for use with the integrated PCB meander antenna.
The MRF24WB0MB comes with an ultra miniature coaxial connector (U.FL) and is approved for use with a list of pre-certified antennas.
The MRF24WB0MA/MRF24WB0MB modules are designed to be used with Microchip’s TCP/IP software stack. The software stack has an integrated driver that implements the API that is used in the modules for command and control, and for management and data packet traffic.
The combination of the module and a PIC running the TCP/IP stack results in support for IEEE Standard 802.11 and IP services. This allows, the immediate implementation of a wireless web server.
The MRF24WB0MA/MRF24WB0MB modules have received regulatory approvals for modular devices in the United States (FCC), Canada (IC), and Europe (ETSI). The modular approval removes the need for expensive RF and antenna design, and allows the end user to place the modules inside a finished product and not require regulatory testing for an intentional radiator (RF transmitter).

MRF24WB0MA/B主要特性:
• IEEE Std. 802.11-compliant RF Transceiver
• Serialized unique MAC address
• Data Rate: 1 and 2 Mbps
• IEEE Std. 802.11b/g/n compatible
• Small size: 21mm x 31mm 36-pin Surface Mount Module
• Integrated PCB antenna (MRF24WB0MA)
• External antenna option (MRF24WB0MB) with ultra miniature coaxial (U.FL) connector
• Range: up to 400m (1300 ft.)
• Easy integration into final product – accelerates product development, provides quicker time to market
• Radio regulation certification for United States (FCC), Canada (IC), Europe (ETSI) and Japan (ARIB)
• Wi-Fi® certified (WFA ID: WFA7150)
• Designed for use with Microchip microcontroller families (PIC18, PIC24, dsPIC33, and PIC32) with downloadable Microchip TCP/IP Stack
Operational:
• Single operating voltage: 2.7V–3.6V (3.3V typical)
• Temperature Range: -20℃ to +85℃ extended commercial
• Simple, four-wire SPI interface with interrupt
• Low-current consumption:
- RX mode – 85 mA (typical)
- TX mode – 154 mA (+10 dBm typical)
- Sleep – 250 μA (typical)
- Hibernate – <0.1 μA (typical)
RF/Analog Features:
• ISM Band 2.400–2.484 GHz operation
• 14 Channels selectable individually or domainrestricted
• DSSS Modulation
• Data Rate – 1000 kbps
• -91 dBm Typical sensitivity at 1 Mbps
• +10 dBm Typical output power with control
• Integrated low phase noise VCO, RF frequency synthesizer, PLL loop filter and PA
• Digital VCO and filter calibration
• Integrated RSSI ADC and I/Q DACs, RSSI readings available to host
• Balanced receiver and transmitter characteristics for low power consumption MAC/Baseband Features:
• Hardware CSMA/CA access control, automatic ACK, and FCS creation and checking
• Automatic MAC packet retransmit
• Hardware Security Engine for AES and RC4-based ciphers
• Supports 802.1x, 802.1i security: WEP, WPA-PSK, and WPA-2-PSK.

MRF24WB0MA/B应用:
• Utility and Smart Energy
- Thermostats
- Smart Meters
- White Goods
- HVAC
• Consumer Electronics
- Remote Control
- Internet Radio
- Home Security
- Toys
• Industrial Controls
- Chemical Sensors
- HVAC
- Security Systems
- M2M Communication
• Remote Device Management
- Location and Asset Tracking
- Automotive
- Code Update
• Retail
- POS Terminals
- Wireless Price Tags
- Digital Remote
• Medical, Fitness, and Health care
- Glucose Meters
- Fitness Equipment
- Patient Asset Tracking

图1.MRF24WB0MA/MRF24WB0MB方框图

图2.MRF24WB0MA/MRF24WB0MB应用电路图

Wi-Fi演示板
The Wi-Fi Comm Demo Board provides a low-cost and portable development system for Microchip’s MRF24WB0MA 802.11b RF Transceiver module.
The Wi-Fi Comm Demo Board is preloaded with the demo software for the user to explore the features of the MRF24WB0MA Wi-Fi module. It is also expandable through an expansion interface, which allows the user to extend its functionality by adding various sensor expansion boards.
Wi-Fi Comm Demo board provides a compact development platform for customers to evaluate Microchip’s Wi-Fi product offering. The demo board comes with onboard MRF24WB0MA Wi-Fi module which is FCC/IC/ETSI certified along with a PIC32 MCU.

Wi-Fi演示板主要特性:

Wi-Fi演示板包括:
• Wi-Fi Comm Demo Board
• 2 AAA Lithium Batteries
• Wi-Fi Comm Demo Board Information Sheet

图3.Wi-Fi演示板外形图

图4.Wi-Fi演示板布局图

Wi-Fi演示板主要特性和元件:
1. MRF24WMB0MA RF Transceiver module
2. PIC32MX695F512H 32-bit microcontroller
3. MCP1642 +3.3V Boost regulator
4. Three status indicator LEDs
5. One push-button switch for user input
6. Power ON/OFF slider switch
7. 6-pin debug port
8. 8-pin sensor port

图4.Wi-Fi演示板电路图