ANT Forum

Hello everyone I started studying ANT for a new application in low power wireless. As always at the beginning I got confused and I need some advice:
I have to realize a system composed of small groups formed from a master that controls 6/7 slave. In the same space must coexist about 5/6 groups for a total of 36slave and 6 master. I Thought to assign each group a given radio frequency.
The transmission between the various devices in a group occurs at a low frequency (2/4Hz). Occasionally, however, I have to communicate with only one of the slave devices at relatively high speed (25/30Hz) for 20/30 seconds. I could use burstmode but I read that using burstmode message for long time may cause loss of synchronization for the other channels. I also thought to use an hub with 8 channels for master and dedicate one channel to each slave, but doing so I use all available frequencies ....
Any ANT expert can help me to find the right solution      

Hi,

In your topology of around 5-6 slaves to each master, you could use a shared channel where 1 master controls the communication to many slaves if you need to conserve individual ANT channels, but typical ANT channel topologies work significantly differently from other comparable protocols, in ANT typically the master is the device which needs to broadcast and the slave is the device which needs to collect data.

So in your case it would likely be easier to reverse the topology and have your slaves become masters and vice versa. This way your peripheral nodes can decide the rate at which they would like to transmit, and there are 8 individual channels on each device, so your central nodes could easily just use those to receive from the 5-6 peripheral nodes.

If you wished to have only 1 central node you could use use an ANT Scanning Mode to be able to communicate with all of the peripheral nodes simultaneously, at the cost of power consumption for the scanning node.

Up to 300 Hz of ANT transmissions can coexist on the same RF channel in the same area so you don't necessarily need to have each group transmit on a different RF channel or even use bursting. (30*2Hz + 6*25Hz = 210Hz)

Recommended reading would be:
ANT Basics
Starting your project
ANT Message Protocol and Usage
AN02 Device Pairing
AN07 Auto Shared Channel Master Example
...

Cheers      

Thanks Harrison for the very clear answer
Unfortunately I can not use a single central node, because slaves are distributed in an area with a radius of about 40/50mt.
Good idea to swap the roles of master and slave.
Thanks I read appnotes.