Sidedbar: Comparing ANT and ZigBee

• The out-of-box experience for the developer;
• The relative effort to develop the same application using standard modules;
• The quality, accuracy and comprehensiveness of the supplied documentation;
• The quality and performance of the supplied firmware drivers, API's and sample application code;
• The performance of the demo systems once implemented;
• The cost and size of the wireless sensor modules.

The development kits were used to set up a simple security system designed to display the use of low power wireless end devices for communication from various remote alarm sensors back to a central application running on a PC.

In addition, the low power devices were also used to demonstrate some home automation capabilities such as a light switch, fan motor switch and fan motor controller with variable speed. Finally, the network was designed to demonstrate a network node configured to extend the network range by using the device as a relay or router.

Two separate systems were implemented, one for the ANT SensRcore devices and another for a competitive ZigBee product. Both modules have a similar feature set including the capability to access external digital and analog I/O without the addition of another microcontroller or custom firmware development. In each case, a system utility or tool was supplied from the vendor to configure the modules for the intended I/O setup and operation.

Both implemented systems had an identical network design and similar PC application with only minor differences based on the product specific interface requirements. Each is capable of supporting 10 devices with a mix of alarm sensors, automation (fan motor and fan switch, light switch), siren and a relay. Both applications were configured as follows:

• 1 siren device.
• 1 relay device
• 1 light switch device that is behind the relay module.
• 1 fan switch complete with a rotary adjustment for a variable speed motor.
• 1 fan motor controller that connects directly to the fan motor.
• 5 alarm sensors (2 window sensors, 1 door switch, 1 break glass sensor, 1 motion sensor)

Each device in the network requires a separate ANT or ZigBee module. In addition, a USB stick with an ANT module is required at the PC and an additional ZigBee device is required at the PC on the serial port.

The message period on the ANT network is variable depending on the number of devices connected to the network. For this implementation, it was decided that it was desirable to have the devices communicate at a very high rate of approximately 3 per second.

This was required to have a reasonable response time for sensor devices that triggered and to get data to/from automation devices. Based on this, a 32Hz message period was chosen to get around 3 per second from each device. ANT network details:

• The main network was a shared address network with the PC as the master node. Slave addresses are configured manually;
• The main network used an RF freq of 2477 MHz;
• Each sensor device used a pre-programmed slave network address as defined in each of the configuration files for the device;
• The sensor device was "1" normally and "0" on alarm condition;
• The devices were set up with a message period of 32 Hz;
• The output devices (siren and light switch) were set up in a similar manner;
• The fan motor pot device was set up as an analog-to-digital input;
• The fan motor controller was setup to use four outputs to determine the fan motor speed.
• Output 0 was used to indicate on/off, while outputs 1 to 3 were used to indicate the speed of the fan;
• The second component of the network was a relay (router) device that was intended to demonstrate that the range of the network could be extended by forming a second network behind a relay device. This relay network operated as a separate shared address network behind the relay;
• The relay network used an RF freq of 2478 MHz;
• Each sensor device used a pre-programmed slave network address as defined in each of the configuration files for the device;
• The only device behind the network was a light switch.

The ZigBee network was set up in a star topology with the PC acting as the coordinator node. The end devices were attached to the coordinator. A relay (router) device was used to extend the range for any end device. Any device could connect to either the coordinator or the relay, and any device could act as a router and an end device. Unfortunately, routers were always on, and as such required mains power.

ZigBee network details:

The relay device was set up with a standard relay (router). Any device could connect to the relay (router) to extend its distance. The relay did not sleep and therefore used a lot of power.

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