原标题：Silabs EM35x高性能ZigBee设计方案

　　Silabs公司的EM351和EM357是高度集成的系统级芯片(SoC),包括有2.4 GHz, IEEE 802.15.4-2003兼容的收发器,32位ARM® Cortex-M3 MCU,闪存和RAM存储器,以及用来ZigBee系统的外设.主要用在智能电网,建筑物自动化和控制,家庭自动化和控制,安全和监视以及通用的ZigBee无线传感器网络.本文介绍了EM351/EM357主要特性,框图,典型应用电路以及采用RFMD RF6525的EM35x参考设计电路图,材料清单和PCB设计文件图.

　　The EM351 and EM357 are fully integrated system-on-chips that integrate a 2.4 GHz, IEEE 802.15.4-2003-compliant transceiver, 32-bit ARM® Cortex-M3 microprocessor, flash and RAM memory, and peripherals of use to designers of ZigBee-based systems.

　　The transceiver uses an efficient architecture that exceeds the dynamic range requirements imposed by the IEEE 802.15.4-2003 standard by over 15 dB. The integrated receive channel filtering allows for robust co-existence with other communication standards in the 2.4 GHz spectrum, such as IEEE 802.11-2007 and Bluetooth. The integrated regulator, VCO, loop filter, and power amplifier keep the external component count low. An optional high performance radio mode (boost mode) is software-selectable to boost dynamic range.

　　The integrated 32-bit ARM® Cortex-M3 microprocessor is highly optimized for high performance, low power consumption, and efficient memory utilization. Including an integrated MPU, it supports two different modes of operation—privileged mode and user mode. This architecture could allow for separation of the networking stack from the application code, and prevents unwanted modification of restricted areas of memory and registers resulting in increased stability and reliability of deployed solutions.

　　The EM351 has 128 kB of embedded flash memory and the EM357 has 192 kB of embedded flash memory. Both chips have 12 kB of integrated RAM for data and program storage. The Ember software for the EM35x employs an effective wear-leveling algorithm that optimizes the lifetime of the embedded flash.

　　To maintain the strict timing requirements imposed by the ZigBee and IEEE 802.15.4-2003 standards, the EM35x integrates a number of MAC functions, AES128 encryption accelerator, and automatic CRC handling into the hardware. The MAC hardware handles automatic ACK transmission and reception, automatic backoff delay, and clear channel assessment for transmission, as well as automatic filtering of received packets. The Ember Packet Trace Interface is also integrated with the MAC, allowing complete, non-intrusive capture of all packets to and from the EM35x with Ember development tools.

　　The EM35x offers a number of advanced power management features that enable long battery life. A high-frequency internal RC oscillator allows the processor core to begin code execution quickly upon waking. Various deep sleep modes are available with less than 1 μA power consumption while retaining RAM contents. To support user-defined applications, on-chip peripherals include UART, SPI, TWI, ADC, and general-purpose timers, as well as up to 24 GPIOs. Additionally, an integrated voltage regulator, power-on-reset circuit, and sleep timer are available.

　　Finally, the EM35x utilizes standard Serial Wire and JTAG interfaces for powerful software debugging and programming of the ARM Cortex-M3 core. The EM35x integrates the standard ARM system debug components: Flash Patch and Breakpoint (FPB), Data Watchpoint and Trace (DWT), and Instrumentation Trace Macrocell (ITM).

　　Target applications for the EM35x include the following:

　　Smart Energy

　　Building automation and control

　　Home automation and control

　　Security and monitoring

　　General ZigBee wireless sensor networking

　　EM351/EM357主要特性:

　　-32-bit ARM® Cortex -M3 processor

　　-2.4 GHz IEEE 802.15.4-2003 transceiver & lower MAC

　　-128 or 192 kB flash, with optional read protection

　　-12 kB RAM memory

　　-AES128 encryption accelerator

　　-Flexible ADC, UART/SPI/TWI serial communications, and general purpose timers

　　-24 highly configurable GPIOs with Schmitt trigger inputs

　　Industry-leading ARM® Cortex -M3 processor

　　-Leading 32-bit processing performance

　　-Highly efficient Thumb-2 instruction set

　　-Operation at 6, 12, or 24 MHz

　　-Flexible Nested Vectored Interrupt Controller

　　Low power consumption, advanced management

　　-RX Current (w/ CPU): 26 mA

　　-TX Current (w/ CPU, +3 dBm TX): 31 mA

　　-Low deep sleep current, with retained RAM and GPIO: 400 nA without/800 nA with sleep timer

　　-Low-frequency internal RC oscillator for low-power sleep timing

　　-High-frequency internal RC oscillator for fast (110 μs) processor start-up from sleep

　　Exceptional RF Performance

　　-Normal mode link budget up to 103 dB; configurable up to 110 dB

　　-–100 dBm normal RX sensitivity; configurable to –102 dBm (1% PER, 20 byte packet)

　　-+3 dB normal mode output power; configurable up to +8 dBm

　　-Robust Wi-Fi and Bluetooth coexistence

　　Innovative network and processor debug

　　-Packet Trace Port for non-intrusive packet trace with Ember development tools

　　-Serial Wire/JTAG interface

　　-Standard ARM debug capabilities: Flash Patch & Break­point; Data Watchpoint& Trace; Instrumentation Trace Macrocell

　　Application Flexibility

　　-Single voltage operation: 2.1–3.6 V with internal 1.8 and 1.25 V regulators

　　-Optional 32.768 kHz crystal for higher timer accuracy

　　-Low external component count with single 24 MHz crystal

　　-Support for external power amplifier

　　-Small 7x7 mm 48-pin QFN package

　　图1.EM351/EM357框图

　　图2.EM351/EM357典型应用电路图

　　典型应用电路中材料清单(BOM):

　　EM35x开发套件

　　The EM35x Development Kit is used for application design and development. The Development Kit contains a variety of hardware for quickly creating a hardware prototype, links to Silicon Labs stack software such as EmberZNet or Silicon Labs Thread, and various tools that enable the development of your application software.

　　The Development Kit includes a development environment, such as Ember Desktop, which facilitates application development and debugging. A compiler, such as IAR-EWARM, is also one of the kit’s software components. Debug Adapters (ISA3s) incorporate Power-over-Ethernet (PoE) capability, which can simplify node deployment in the test environment. Breakout Boards provide a direct connection for debugging customer-designed hardware.

　　The EM35x Development Kit development board set has three major hardware components:

　　• EM35x Breakout Board

　　• EM35x Module

　　• Debug Adapter (ISA3)

　　EM35x开发套件包括:

　　The EM35x Development Kit also includes the following components:

　　• US-to-Multinational AC Plug Power Adapter Kit

　　• Power-Over-Ethernet (PoE) Switch

　　• USB Power Adapters

　　• Miscellaneous Cables (USB, DEI, Packet Trace Port, and RF Coax)

　　图3.EM35x开发套件外形图

　　图4.EM35x分线板外形图

　　图5.EM35x分线板外和EM35x模块安装图

　　采用RFMD RF6525的EM35x参考设计材料清单: