ANT Forum

Hi,

I am working on a project which is using ANT communication and we have chosen the nRF24AP2-8CH chip. At the moment we having some problems and i hope some one on this forum can help us.

Case:
We are using 2 channels, 1 master and 1 slave.

Master channel:
â?¢ Channel 0
o PARAMETER_TX_NOT_RX,
o period time 8hz
o freq 60

Slave channel:
â?¢ Channel 1
o PARAMETER_RX_NOT_TX,
o period time 4hz
o freq 66
o low priority enabled 12,5 sec
o high priority search is disabled 0.

The high priority search is disable (search time 0) because we donâ??t want to interrupt other channels. But for some reason the master channel is affected by the search that is perform on the slave channel.

First I open the master channel 0 then the slave channel 1.
For this case there is no external master for channel 1 and there for the channel will be closed after 12.5 sec and reopend by the microcontroller.

After +/-10.5 sec I start receiving collision(ch0) messages from the ANT chip. In total 9 times.
The last message is compose of the following events:
EVENT_RXSEARCH_TIMEOUT (ch1), EVENT_CHANNEL_COLLISION (ch0) , EVENT_CHANNEL_CLOSED (ch1)

The collisions are visible on the receiving end of channel 0 as EVENT_RX_FAIL.
(PC with ANTware II , USB dongle AP1 chip.)

With a logic analyzer I have checked the communication between microcontroller and ANT chip.
I have confirmed that the commands to disabled the high priority search and set the low priority search time (5 =12,5sec) are acknowledged by the ANT chip.

Question:
â?¢ why do I get the collisions and how can I solve this?      

I tried re-creating your scenario using only ANTware (quite easy to do if you have not already), but I could not reproduce your issue. With high priority search disabled, I never saw channel collisions. When I turned on high priority search, I did see collisions immediately on search.

On possibility is that you are using an older AP2 module. On older AP2 modules, the way the search works is that after your low priority search times out, ANT would automatically do an extra 2.5 seconds of high priority search at the end, even if it was disabled. This is fixed since about AP2 version 1.02. Can you tell me what version you have? It should be on the modules you are using.      

i have checked the version of the AP2 chip we used to get these results and its an AP2 1.01 version chip so that explains the +/-9 collisions.

I have also check the AP2 chips we got a few weeks ago and the ones I have tested are all 1.06 version AP2 chips.

So I visited the Nordic website to find out what kind of problems are fixed in the different versions but I could not find this information on the website.

- Is this information of version changes available?      

Yes, there is information available on the differences between the different versions of the AP2 in the AP2 Errata document, located in the downloads section of the website.

ANT AP2 RF Transceiver Module Errata:
http://www.thisisant.com/images/Resources/PDF/ap2_rf_transceiver_module_errata.pdf