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Wireless Protocols

Unison and DSPnano have been designed to support a broad set of wireless protocols. These protocols include the following:

The RoweBots Bluetooth stack comes in two flavours: an AT command set or spi interface module and an HCI interface module. The advantage of the AT or SPI interface is that the entire protocol stack can run on the wireless module. Typically this is done for SPP or serial profiles. In contrast the HCI interface approach runs the balance of the protocol stack on the MCU or MPU and then the developer has a much broader set of choices for the profile that is used, including audio, health data, handsfree and much more. These wireless protocols offer complete end to end protocol solutions with full interoperability and POSIX device interfaces.

WiFi wireless protocols provide local area networking using a TCP/IP protocol stack with either IPV4 or IPV6. As a result, WiFi support is transformed into a network driver for these stacks with extra interfaces to choose a wireless network or terminate a wireless network and select another network for communication.

Zigbee and 802.15.4 low cost wireless protocols are very similar. The radio module used is identical and the zigbee stack is provided by the module developer along with the various low cost wireless options. These protocols are ideally suitable for a UDP or data gram sockets based interface. This plays to the strength of these wireless networks which are subject to interference and signal dropout. Demonstration programs provide seamless integration and operation in 10 minutes out of the box.

GPRS and LTE radios are supported in modules accessing the cell network to provide very wide area networking. Typically these connections are setup using an AT command set or SPI interface to establish a call and then TCP/IP and PPP are used to provide a full networking service over the GPRS radio.

Support for GPS and RFID / Near Field Communications wireless protocols using standard radio modules are easily intergrated into the system. Using standard modules interfaces range from SPI to AT command sets. Standard POSIX file interfaces are provided to read data from these devices.

6loWPAN isa new wireless protocol. It provides TCP and UDP services over 802.15.4 mesh radio networks. It integrates ideas associated with low power and intermittent node up times to minimize power consumption using two other new protocols called ROLL and RPL. Interesting the idea of routing at the mesh level has been rejected in favour of dynamic routing at the IP level.

Contact us for further information on our wireless protocols and our partner's modules.

Bluetooth v4

Bluetooth v4 is the latest version of bluetooth and it is used in a wide variety of applications. It has essentially the same structure and services as previous bluetooth versions with the exception of support for low power sensor applications with fast startup.

Unison Bluetooth v2.1

Unison Bluetooth has support for Bluetooth version 2.1 with a comprehensive set of profiles. It is fast and easy to use and configure for specific applications. It comes with assymetric profile support as illustrated in the video above. For example, both ends of the headset profile are supported so headset devices may be supported or devices which require headsets may be supported.

Unison Bluetooth can be setup to work in three ways:

  • ● It can run inside a module and provide bluetooth support to users typically accepting commands through an AT command set.. The module developer has to implement this solution and it is not intended for anyone but module developers.
  • ● Unison Bluetooth can provide the high level support on an MPU, MCU or FPGA to use a module with a complete Bluetooth stack on board.
  • ● Unison Bluetooth can run on the MCU, MPU or FPGA and provide the complete stack from the HCI interface upwards. This is the most common way to run Unison Bluetooth because it can then have any profile that the user wants or even combined profiles.

Typically modules put SPP or serial port profile in the module. Sometimes more functionality is added but often it is not the right profile, or not the exact profile that is required and the small MCU that it runs on is insufficient for good performance. For this reason, and the fact that HCI based modules and chips are far less expensive, the third option is preferred.

The current architecture of the second and third elements in this list are shown in the following diagram:

The profiles offered today off the shelf for Bluetooth are:

  • ● Serial port profile (SPP)
  • ● Hands free profile (HFP)
  • ● Health data profile (HDP)

Please contact the factory for a current list.

Other profiles are available on short notice including:

  • ● Head set profile (HSP)
  • ● BNEP or TCP over Bluetooth
  • ● Advanced Audio Distribution profile (A2DP)
  • ● Personal area network (PAN)
  • ● Synchronization (Sync)
  • ● Human interface device(HID)
  • ● File transfer profile (FTP)
  • ● Dial up networking (DUN)
  • ● Hard copy cable replacement or printer (HCRP)
  • ● Intercom (ICP)
  • ● Object Push (OPP)
  • ● Video distribution profile (VDP)

Note that Unison Bluetooth is priced with various profiles in a consistent manner with all Unison modules. This makes the Unison Bluetooth 2.1 offering one of the most cost effective solutions on the market.

Unison Bluetooth v2.1 Modules

Typical modules provide SPP or serial port profile in the module. Sometimes other profiles are provided but often lack flexibility and features when used like this. In addition performance is often poor because the tiny MCU in the module is doing too much work. The list below is a set of modules that are supported using SPP and HCI. Note that any HCI module will work off the shelf in a few minutes.

  • ● Panasonic 1315
  • ● ST Ericson (consult factory)
  • ● TI WL1271 HCI
  • ● RoweBots CSR HCI module (pending release)

Unison Bluetooh Smart v4


WiFi In Use With Unison

WiFi is the most commonly used wireless protocol used today for short distance communications. This first video shows WiFI used with USB mass storage class on a microcontroller to provide access to a web server via a smart phone.

WiFi is also expected to be widely using in the Internet of Things or if you prefer, Machine to Machine communications. The next video explains how it is more generally used for a variety of purposes.

WiFi is generally the wireless network of choice where high bandwidth is required, coverage needs to be localized and power is not a concern. Today we all use WiFi to access files in a variety of home and business settings with little attention paid to setup and configuration. It is a slmple tool in our society today.

WiFi Design and Implementation

When talking about WiFi, we are actually talking about a range of protocols and communications specifications which span the last 1.5 decades. Today we have 802.11a, b, g, to 802.11n with a maximum of 600Mbits/second. New standards like 11ac and 11ad. The differences between these from a user point of view are not relevant with the exception of the security standards (more below).

The various data rates and improvements are achieved through larger QAM constellations (8X8 or 256 or a 1 byte qbit) , Orthogonal Frequency Division Multiplexing (ODFM) which uses multiple frequencies and sends multiple bits this way, Direct Sequence Spread Spectrum (DSSS) and combinations of these strategies. Date rates are expected to be pushed over 1Gbit/sec for 11ac and up to 7Gbits/sec for 11ad.

WiFi runs in the 2.4GHz ISM band, and 5GHz bands. Channels are spaced 5MHz apart in the 2.4GHz band. The 5GHz band is considerably more complex.

Security in the WiFi domain is quite important and the initial WEP security was easily broken. Newer versions such as WPA and WPA2 are much stronger and these security enhancements offer good protection today. In enterprise WiFi environments, typically a Radius client server model is used along with EAP-TLS support.

WiFi Integration With TCP/IPv4/IPv6

At the bottom of the diagram you can see two possible collections of network interfaces. One set of interfaces uses PPP and a serial data stream to send packets over either a wireline or wireless network. This is shown on the right. The second interface on the left is for WiFi.

On the lower left of the diagram you can see there is a network interface consisting of both wireline and wireless connections like the right hand side. One of the wireless connections is WiFi. What this means is that as IP packets arrive or get sent out, they can be routed to/from this interface to the correct part of the system for processor or output as required. This selection of the WiFi interfaces takes care of the routing of packets out onto the WiFi radio and brings return packets into the protocol stack for processing.

Above this interface you can see a WiFiSupplicant. This piece of software handles the setup and processing of the WiFi with respect to security. As discussed above, it would make sure that the correct WPA and WPA2 security codes were used and the packet should be allowed to proceed into the stack.

As you can see from this diagram, the WiFi packets get processed and become part of the IPv6 and then the TCP packets as they proceed through the system layers. They also go through a TLS/SSL layer and on to higher level protocols. From this it should be clear that the WiFi implementation is tied direclty to the TCP/IPv4/IPv6 stack and that all higher level protocols run over this service.

WiFi Modules

Unison's WiFi support is fast and easy to use and works quickly and easily with a wide set of WiFi modules. It does not work with non-embedded systems modules simply because insufficient support is provided by the silicon and module vendors for these implementations. (This means that you are unlikely able to purchase a USB WiFi dongle and make it work in this environment.)

Supported WiFi modules:

  • ● RedPine
  • ● Microchip

Please consult the factory for a complete list of current modules.


Zigbee offers low data rate, low power mesh networking protocols. Over 300 companies support Zigbee today.

Zigbee really comes in three different flavors today. The first is standard Zigbee based on the second standard. The next one is Zigbee Pro which is based on the second standard and is backward compatible with Zigbee. The third flavor is Zigbee IP which utilizes 6loWPAN, TCP/IPv6 and RPL to extend Zigbee Pro ino the IPv6 networking domain.

ZigBee has a defined rate of 20-250 kbit/s, best suited for periodic or intermittent data or a single signal transmission from a sensor or input device. Applications include wireless light switches, electrical meters with in-home-displays, traffic management systems, and other consumer and industrial equipment that requires short-range wireless transfer of data at relatively low rates. The technology defined by the ZigBee specification is intended to be simpler and less expensive than other wireless networking technologies albeit with less performance and less power.

ZigBee operates in the industrial, scientific and medical ISM band bands ( 868 MHz in Europe, 915 MHz in the USA and Australia and 2.4 GHz worldwide). Data transmission rates vary from 20 kilobits/second at 868 MHz to 250 kilobits/second at 2.4 GHz . The network topologies can be either star, tree or mesh networks. The radio standard from 802.15.4 is used to support both the MAC and physical layers of the network.

Zigbee networks are secured by 128 bit encryption keys. This is typical for other wireless networks today. It offers good security at the present time but will need upgrades in the future as the keys are static.

Four main components are used to build up the Zigbee capabilities as shown in the diagram in a top down fashion. These components are:

  • ● Application objects which are manufacturer specific;
  • ● Zigbee device objects which record: device roles, management of requests to join a network, device discovery and security.
  • ● Applications networking layers
  • ● Networking layer

One of the main advantages of Zigbee has been the ability to go from standby to full operation in 30msec. This is substantially better than Bluetooth 2.1 or WiFi; however with Bluetooth 4.0 the new sensor standard creates a significant advantage for Bluetooth Smart (4.0).

The basic components of Zigbee are shown in the following diagram.

RoweBots Unison RTOS offers three flavors of Zigbee. The first is an AT command or SPI version which interfaces with existing Zigbee modules. The recommended modules for this purpose are:

  • ● Anaran (AIR) modules

The second type of solution is a standard Zigbee Pro solution using an off the shelf 802.15.4 radio. This version operates under direct programmatic control and runs on the microcontroller. This version is factory special order at the current time. The modules used for this include:

  • ● Microchip 802.15.4 radio module
  • ● Texas Instruments 802.15.4 radio module
  • ● Anaren AIR modules

The third type of Zigbee support available is Zigbee IP. This solution can be based on either an Anaren AIR module running Zigbee or the Zigbee PRO solution running on the microcontroller. This is currently a factory special order solution and includes the following components:

  • ● Unison RTOS core
  • ● Unison TCP/IPv6
  • ● Unison 6loWPAN driver with RPL support
  • ● Zigbee PRO or Anaren AIR Zigbee on module

The modules which can be used include:

  • ● Microchip 802.15.4 radio module
  • ● Texas Instruments 802.15.4 radio module
  • ● Anaren AIR modules

Contact RoweBots now to discuss the Zigbee solution you need.


GSM/GPRS, 3G, LTE, GPS, M2M are all the telecommunications main protocols to implement their view of M2M or machine to machine communications. A broader view of M2M would include wireline Internet, WiFi, Bluetooth and Zigbee with networks of wireless sensors. Others see this later implementation as the "Internet of things" or IoT. In this context we will use the telecommunications firms definition for M2M and the telecommunications wireless solutions.

Using standard wireless modems for GSM/GPRS, 3G, LTE and GPS full Internet connetivity with secure access can be added to any application. The basic approach is to run PPP to serialize TCP/IPv4/IPv6 data streams and to use TLS or IPSec to secure the end to end channel. Generally these modems have either an SDIO, SPI or UART interface and this basic operation requires command modes to make the initial connection followed by enabling PPP data communication. Often stay alive packets are required as well to ensure that the link stays up over time.

These modules are relatively easy to use and connect. SDIO offers better performance, UART offers the best ease of use and SPI is a mid-point compromise. The Unison RTOS software requires some trivial customization for control for specfic modules but 99% of this technology is off the shelf.

For a list of theGSM/GPRS, 3G, LTE, GPS modules which have been integrated into the Unison RTOS and used for M2M, please consult the factory.


802.15.4 is an IEEE specification for low power and low data rate radios. ZigBee operates in the industrial, scientific and medical ISM band bands ( 868 MHz in Europe, 915 MHz in the USA and Australia and 2.4 GHz worldwide). Data transmission rates vary from 20 kilobits/second at 868 MHz to 250 kilobits/second at 2.4 GHz .

The network topologies can be either star, tree or mesh networks in Zigbee and proprietary systems that use 802.15.4. The radio standard from 802.15.4 supports both the MAC and physical layers of the network but does not define the topology. The overlay software defines the topology. The radio itself defines point to point connections and star structures.

Typical proprietary protocols which have been ported to the Unison RTOS include:

  • ● TI SimpliciTI
  • ● Microchip MiWi

The standards based protocols which would use the 802.15.4 radios include the following:

  • ● Zigbee
  • ● Zigbee PRO
  • ● Zigbee IP
  • ● 6loWPAN without Zigbee

The frequency ranges supported by various modules are:

  • ● 868.0-868.6 MHz: Europe, allows one communication channel (2003), extended to three (2006)
  • ● 902-928 MHz: North America, up to ten channels (2003), extended to thirty (2006)
  • ● 2400-2483.5 MHz: worldwide use, up to sixteen channels (2003, 2006)

The actual modules that the Unison RTOS works with are:

  • ● Anaren AIR
  • ● Microchip PICtail
  • ● Texas Instruments


6loWPAN is a wireless protocol which provides an IPv6 address and TCP/IPv6 to all nodes in a network using a low data rate 802.15.4 radio. The technologies involved are:

  • ● TCP/IPv6 header compression and decompression
  • ● IPv6 address creation
  • ● Dynamic routing between network nodes
  • ● Ad hoc networking between network nodes
  • ● Static routing between network nodes

The version of 6loWPAN in the video uses static routing at the ipv6 level Because there is no dynamic routing then nodes cannot be automatically added in an adhoc mesh network fashion as you might expect. The reason for this is related to the standardization efforts associated with RPL. Now RPL is agreed and approved, standardization can proceed in a more timely fashion

One of the key things that changed in the standardizaion was the introduction of Zigbee IP which uilizes IPv6 and 6loWPAN and RPL integrated with the lower levels of Zigbee to produce an integrated TCP/IPv6 - Zigbee solution. This will be available from RoweBots in the future.

The modules used for the implementation of 6loWPAN solutions either with raw use of the 802.15.4 radio or as part of a more comprehensive Zigbee IP solution include:

  • ● Anaren AIR modules
  • ● TI 802.15.4 radios
  • ● Microchip 802.15.4 radios

Please contact us immediately for more information on 6loWPAN.

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Rowebots Limited

RoweBots was founded in May 1987 by a group of Univer­sity researchers. From the outset, RoweBots had its roots in real-time multiprocessor software and has broadened into an embedded signal processing systems company today.

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