Limits and use of frequenzy hopping "on the fly"

[Seidel]

Hi, i am currently modifikat a working ANT-System (Master with multiple Slaves) with the NRF51422 and Softdevie 1.0 to be robust against in band disrupters. My idea is to change the Frequency every ANT-Block (TX and RX). I read in „ANT Message Protocol and Usage, Rev 5.0“ in chapter "5.2.2 RF Frequency" the Frequency can be changed on the fly. Ok thats good, but when schould i do this, theres no EVENT such as "beginning of ANT" or "finished".

My first test implementation with static "hopping-tabble" works obiously, butist not stable, the master and slaves lost synchronisation.

Thanks for every hint!

[Asbjørn]

You can't modify the frequency selection when the radio is active, but as long as the radio part is done, you can safely switch. I would say the static hopping table is the best way to go in such a case, but you should probably add ACK to your communication. That way you could after every time a package is ACKed, switch frequency. That way both sides would be a little more in synch the when the hopps will occur.

If ACKs are not an option, a timer on both sides that will reset every time a packages is sent/received might be a way to go.

What do you see when you say that it's not stable? Do you drop a few packages or many?

[Seidel]

my failure was, that i first use a frequency table with increment frequency. my implementation was wrong, so the master an the slave use frequencies which where neightbors. ANT itself could hear telegramms on the neightbor frequency so it worked a "little bit". Now i correkt this and all works so far.