EM357-RTR datasheet(22/241 Pages) SILABS

22 / 241 page

Rev 1.3

3. Functional Description

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



The technical data sheet details the EM35x features available to customers using it with Ember software.

EM357-RTR 数据表(PDF) 22 Page - Silicon Laboratories

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