FAQ's

Please note - the answers to most questions can be found in the manuals

Further information and questions concerning Ember and ZigBee, please see www.ember.com and www.zigbee.org

Choosing ZigBee

•  What is the ZigBee Alliance?
•  Why do we need ZigBee?
•  What is the EmberZNet Stack?
•  How does the ETRX2 implement ZigBee?
•  Where would my application sit?
•  What do I need to start my development?
•  What about FCC, EN and CE compliance?

Telegesis General Questions

• Do Telegesis make other products apart from ZigBee devices?

• Do Telegesis make 868MHz and 915MHz ZigBee devices?

Programming ETRX Modules

• Does the ETRX2 support JTAG?
• Does the ETRX2 support an SPI or I2C interface?
• How can I upload firmware to the ETRX2?
• I need customisation of the firmware for my application!
• I want to write my own firmware.
• Can I run other applications than Ember based ZigBee?

 

Using  ETRXn Modules

• What range can be expected?
• Is a version available with higher RF power?
• Can I mix ETRX1s and ETRX2s in the same network?
• Can I mix R1xx and R2xx firmware in the same network?
• My ETRXn won't communicate with other manufacturers' ZigBee devices
• Do we have Linux drivers for ETRX2CF and ETRX2USB?
• Can the PAN extend over a greater number of hops?
• What power mode should a unit to be in, in order to be detected by the network?
• The over the air data rate is 250kbps but the serial link speed is recommended not to exceed 19200bps. What is the maximum throughput of the ETRX1 module?
• I'm using R1xx firmware. One of the modules no longer connects to any other module!
• I'm using R2xx firmware. One of the modules no longer connects to any other module!
• I can't talk to a module serially.
• Where can I get 2.4GHz external antennas from?

 

Choosing ZigBee

• What is the ZigBee Alliance?

The ZigBee Alliance is an association of companies working together to enable reliable, cost-effective, low-power, wirelessly networked, monitoring and control products based on an open global standard.

The goal of the ZigBee Alliance is to provide the consumer with ultimate flexibility, mobility, and ease of use by building wireless intelligence and capabilities into every day devices. ZigBee technology will be embedded in a wide range of products and applications across consumer, commercial, industrial and government markets worldwide. For the first time, companies will have a standards-based wireless platform optimised for the unique needs of remote monitoring and control applications, including simplicity, reliability, low-cost and low-power. http://www.zigbee.org/

• Why do we need ZigBee?

Until The ZigBee Standard was ratified in December of 2004 there was no standard approach that addressed the unique needs of most remote monitoring and control applications. The ZigBee Standard enables the broad-based deployment of reliable wireless networks with low complexity, low cost solutions and provides the ability for a product to run for years on inexpensive primary batteries (for a typical monitoring application). It is also, of course, capable of inexpensively supporting robust mesh networking technologies.

• What is the EmberZNet Stack?

The Telegesis ETRX2 utilises the EmberNet/EmberZNet protocol stacks and can form a self-organizing, self-healing wireless networking platform based on the ZigBee specifications. The EmberZNet supports a variety of network topologies for wireless monitoring and control applications, including mesh, star, and cluster tree. Applications running the EmberZNet stack can be interoperable with other ZigBee nodes. EmberZNet provides all of the standard benefits that come with ZigBee including: flexible topologies, high security, broad interoperability, low cost, long battery life, and integrated network management. In addition, EmberZNet applications can take advantage of the industrial strength reliability and unprecedented ease of use of the Ember Transport Layer capabilities.

Until now, much of the cost of deploying sensing and control devices was in installing the network to connect them. With EmberZNet, the value, like the network, is embedded in the devices themselves. EmberZNet's self-organizing, self-healing mesh algorithms produce networks that are reliable, flexible, secure, and easy to use. Adding devices only makes EmberZNet sensing and control networks stronger and more efficient. Designed from the ground up for developers of sensing and control products, the EmberZNet product suite enables rapid development and deployment of embedded wireless networks that virtually "see around corners," and that have no single point of failure.

The EmberZNet Protocol Stack is a compact, scalable implementation of the ZigBee specifications which translates into lower cost MCU options for device manufacturers. The stack is available in different configurations optimized for the various ZigBee node types; PAN coordinators, full function devices, and reduced function devices. The stack is already available for several microprocessor platforms supported by Ember.

• How do the ETRX2 and ETRX3 modules implement ZigBee?

The ETRX2 and the ETRX357 are supplied with firmware that runs EmberZNet to form a meshing network. Tree, star and cluster tree are not implemented as the mesh topology is the most useful. On top of the Ember firmware we have put our AT command-like user interface, so that the user does not have learn all the details of controlling a PAN.

• Where would my application sit?

There are a number of options. When using the Telegesis AT Style command interface the application sits on a host microcontroller which is external to the ETRX1 and ETRX2 module. Additionally the ETRX2 can be used stand-alone using the pre-defined functionality defined in the non-volatile S-Registers, which hold the configuration data of the ETRX2 wireless meshing module. If you decide to develop your own firmware instead of using the Telegesis "AT style" command interface then it can run on the XAP2b processor on the ETRX2 module.

• What do I need to start my development?

The quickest and easiest way to begin your development is to use a ETRX2DVK+ development kits but if you wish, you could integrate the ETRX2 on to your own carrier boards. To connect the ETRX2 to a PC you will need to use an RS232 level converter or alternatively connect the ETRX2 straight to a host microcontroller.

• What about FCC, EN and CE compliance?

The ETRX2 wireless meshing module with the on-board antenna complies with EN, CE and FCC regulations and carries an FCC ID which allows it to be integrated into products which don't need to be re-tested for radio compliance - subject to the following.

The ETRX2 has been tested and approved by a certified laboratory for RF Transmission, EMC and for general product safety.

Using the integrated Antenna it conforms with EN300 440, EN 300 328 (Europe) and FCC CFR 47 Part 15 (USA).

This device complies with Part 15 of the FCC rules. Operation is subject to the following two conditions: (1) this device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation.

ETRX1 FCC ID: S4GETRX1

ETRX2 FCC ID: T7VEM250A

Please Note:

The ETRXn device carries FCC authorization and is marked with the FCC ID Number. Whilst any device into which this authorized module is installed will not normally be required to obtain FCC authorization, this does not preclude the possibility that some other form of authorization or testing may be required for the finished device.

When the ETRXn module is integrated inside another device/product, then the outside surface of that device/product must display a label referring to the enclosed module. This exterior label can use wording such as "Contains Transmitter Module FCC ID: S4GETRX1" or "Contains FCC ID: S4GETRX1" although any similar wording that expresses the same meaning may be used. If in doubt, please check with a certified laboratory of the FCC.

See Certification for details of the current certification.

 

Programming the ETRXn

• Does the ETRXn module support JTAG?

With the ETRX1, yes, but by default the JTAG functionality is disabled. It can be enabled by programming the respective fuse of the ATmega128. Enabling JTAG sacrifices A/D1, A/D2 as well as I/O7 and I/O6. If you require a high quantity of modules with JTAG enabled the respective fuse can be programmed in factory for you.

The ETRX2 does not support JTAG.

• Does the ETRX2 support an SPI or I2C interface?

Not with the default AT command firmware. The physical peripheral connections are present to utilize this with custom firmware.

• How can I upload firmware to the ETRX2?

On pre-programmed modules the Ember bootloader is installed which can be used to download new firmware over the air or via the serial port. This bootloader can be accessed using the Telegesis Terminal software. Note that after downloading your own firmware you may not be able to access this bootloader any longer unless you include it in your own program.

Alternatively the 10 Way ISP connector on the devkit can be used to download new firmware using an AVR programmer. If enabled JTAG can be used to program the ATmega.

• How can I upload firmware to the ETRX2?

The Ember bootloader can be used as with the ETRX1, or the ISP connector of certain devices can be attached to an Ember Insight Adaptor.

• I am an existing Ember customer and have Ember Studio on my PC. Do the ETRX1 modules interact with Ember Studio?

Yes, they do. Use the gateway node supplied by Ember and the ETRX1 modules will be detected happily.

• I need customisation of the firmware for my application!

Please contact us about an extension of the AT-command dictionary.

• I want to write my own firmware.

Feel free to develop your own firmware, however we can only support you on the hardware side. Please contact Ember directly for support on their software stack. The ETRXn modules are not write-protected.

• Can I run other applications than Ember based ZigBee?

You can develop and use any firmware based on the ATmega128 and EM2420 and run it on the ETRX1 modules. Firmware for the EM250 in the ETRX2 must be written using an Ember developer kit - see Ember Tools

Using the ETRXn

• What range can be expected?

The range depends on a lot of factors like the surroundings in which the devices are used and the product they are integrated into. With the on board antenna in urban environment a range between 30-60 metres can be expected but free space ranges of over 200 meters have been experienced. If you require a greater range the use of a suitable external antenna can improve the performance of the module.

• Is a version available with higher RF power?

Yes- see ETRX2-PA

• Can I mix ETRX1s and ETRX2s in the same network?

Yes, providing they have the same firmware version

• Can I mix R1xx and R2xx firmware in the same network?

Definitely not, they will not mesh together. In fact, it is better not to mix firmware versions at all.

• My ETRXn won't communicate with other manufacturers' ZigBee devices

For nodes to form a network, they must all be using the same protocol stack profile and stack parameters. Furthermore, for communication between nodes in a network they must be running the same application profile. Ours, using our AT command set, is a private profile not a public one, Please see the notes in our documents (eg the AT Command Manual) regarding ZigBee compliance, for example 'an end product containing an ETRX1 or ETRX2 based on firmware revisions R2xx cannot yet be certified to be "ZigBee^TM network capable" or "ZigBee^TM compliant"' and 'the ETRX1 and ETRX2 run a private application profile'. Our devices incorporate the EmberZNet2.3 or 2.5 protocol stack and a meshing network rather than a tree topology.

• Do we have Linux drivers for ETRX2CF and ETRX2USB?

The drivers are all supplied by the manufacturers of the CF and USB bridge chips. Try the following:-

Elan Digital Systems for the CF card
Silicon Labs for the USB stick

• Can the PAN extend over a greater number of hops?

Unicasts will travel up to 6 hops and broadcasts can travel 10 hops. These cannot be increased without compromising the performance, and the user cannot alter these limits.

• What power mode should a unit to be in, in order to be detected by the network?

The unit needs to be in power mode 0 i.e. fully awake in order to interact with the network. If you need to save power you should use the leaf node approach. A leaf node has no routing responsibilities and therefore can be put to sleep at any time. When woken up a leaf node can transmit its data to the coordinator either in predefined intervals or event triggered.

• The over the air data rate is 250kbps but the serial link speed is recommended not to exceed 19200bps. What is the maximum throughput of the ETRXn module?

250kb/s is the raw bit rate within a radio packet and is not a guide to data throughput. The ETRXn has been designed to allow stable wireless meshing connectivity for remote control, metering and automation purposes. Due to its nature it isn't suitable for time-critical control or high-speed data like audio/video or file transfer (unless you have a lot of time). If you intend to do any of this you should look for a different technology.

• I'm using R1xx firmware. One of the modules no longer connects to any other module!

In order to talk to one another, all modules need to have the same channel and PAN ID. These values are stored in registers S0 and S1. Make sure those Registers are set identical on all modules. If you are unsure, use the AT&F command to reset each module to its factory defaults.

• I'm using R2xx firmware. One of the modules no longer connects to any other module!

You have more than one PAN in operation. A coordinator will maintain its PAN forever even if it is the only member. Disassociate your local device from its PAN and use AT+N to find all the PANs in its vicinity.

• I can't talk to a module serially.

1. Make sure power is plugged in and the module is correctly connected to the socket (if using the Development Kit).
2. Make sure your computer is communicating via the correct COM port.
3. If the register that sets up the UART has been modified, the data rate, parity or number of bits of the serial link will have changed. When this is the case you quite often will receive garbage or nothing at all. Try adjusting the Terminal program to match the settings of the ETRXn module, or correct the register over-the-air.
4. The module may have been powered down by putting it into a low-power mode. Try causing an external interrupt as described in the Development Kit manual or simply reset the module.
5. The module may have been set to low power mode by putting it into power mode 2. Try to adjust the data rate to 4800bps which is the only supported data rate in power mode 2 (ETRX1 only).
6. The module may have been set to have a pre-defined functionality which may cause the module to go to sleep even after a reset. Refer to the descriptions of the built-in functionality and the Application Note on how to wake the unit up permanently.
7. If the device has been powered up with pad 10 (for the ETRX2 - A/D2) or pad 8 (for the ETRX1 - I/O5) held low, it will be running its bootloader. Reset it, or see the Development Kit Technical Manual for details of the bootloader.

• Where can I get 2.4GHz external antennas from?

Telegesis can supply a limited selection of antennas - see Telegesis Web Shop There are a number of companies worldwide that do specialise in this area. We can recommend Embedded Antenna Design, Milton Keynes, UK who stock a wide selection of antennas as well as offering a bespoke antenna design capability. www.ead-ltd.com

Do Telegesis make other products apart from ZigBee devices?

No, we specialise in ZigBee modules based around the Ember EM250 and EM357 chips.

Do Telegesis make 868MHz and 915MHz ZigBee devices?

No, only 2.4GHz.