EM260-RTR datasheet(17/50 Pages) SILICONIMAGE

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EM260

Page 17

120-0260-000M Rev 1.1

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Automatic acknowledgement transmission

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Automatic transmission of packets from memory

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Automatic transmission after backoff time if channel is clear (CCA)

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Automatic acknowledgement checking

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Time stamping of received and transmitted messages

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Attaching packet information to received packets (LQI, RSSI, gain, time stamp, and packet status)

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IEEE 802.15.4-2003 timing and slotted/unslotted timing

4.4

Packet Trace Interface (PTI)

The EM260 integrates a true PHY-level PTI for effective network-level debugging. This two-signal interface

monitors all the PHY TX and RX packets (in a non-intrusive manner) between the MAC and baseband modules.

It is an asynchronous 500kbps interface and cannot be used to inject packets into the PHY/MAC interface. The

two signals from the EM260 are the frame signal (PTI_EN) and the data signal (PTI_DATA). The PTI is supported

by Ember Desktop.

4.5

XAP2b Microprocessor

The EM260 integrates the XAP2b microprocessor developed by Cambridge Consultants Ltd., making it a true

network processor solution. The XAP2b is a 16-bit Harvard architecture processor with separate program and

data address spaces. The word width is 16 bits for both the program and data sides.

The standard XAP2 microprocessor and accompanying software tools have been enhanced to create the XAP2b

microprocessor used in the EM260. The XAP2b adds data-side byte addressing support to the XAP2 allowing for

more productive usage of RAM and optimized code.

The XAP2b clock speed is 12MHz. When used with the EmberZNet PRO stack, firmware may be loaded into

Flash memory using the SIF mechanism (described in section 7) or over the air or by a serial link using a built-

in bootloader1 in a reserved area of the Flash. Alternatively, firmware may be loaded via the SIF interface

with the assistance of RAM-based utility routines also loaded via SIF.

4.6

Embedded Memory

The EM260 contains embedded Flash and RAM memory for firmware storage and execution. In addition it

partitions a portion of the Flash for Simulated EEPROM and token storage.

4.6.1

Simulated EEPROM

The EmberZNet PRO stack reserves a section of Flash memory to provide Simulated EEPROM storage area for

stack and customer tokens. The Flash cell has been qualified for a data retention time of >100 years at room

temperature and is rated to have a guaranteed 1,000 write/erase cycles. Because the Flash cells are qualified

for up to 1,000 write cycles, the Simulated EEPROM implements an effective wear-leveling algorithm which

effectively extends the number of write cycles for individual tokens.

The number of set-token operations is finite due to the write cycle limitation of the Flash. It is not possible to

guarantee an exact number of set-token operations because the life of the Simulated EEPROM depends on

which tokens are written and how often.

The EM260 stores non-volatile information necessary for network operation as well as 8 tokens available to the

Host (see document UG100, EZSP Reference Guide). The majority of internal tokens is only written when the

EM260 performs a network join or leave operation. As a simple ballpark estimate of possible set-token

1 See document UG103.6, Ember Application Development Fundamentals: Bootloading, for more information

on the bootloader.

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