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nRF24AP2-USB Product Specification

Figure 8. Channel communication showing forward and reverse directions. Not to scale

At each time slot an ANT channel can transfer user data (8 bytes) both ways as simple broadcasts,

broadcast with acknowledgement from the receiver, or transfer data as bursts (this will extend the time slot

used) to accommodate transfer of larger blocks of user data. The total available payload bandwidth (20

kbps) in an ANT node is shared between active ANT channels through a Time Division Multiple Access

(TDMA) scheme. If a channel time slot comes up, but there is no new data from the master, the master will

still send the last packet to keep the timing of the channel and enable the slave to send data back if

needed.

Each ANT channel available in the nRF24AP2 can for example be configured as a simple unidirectional

(broadcast), or bi-directional independent channel; or as a more complex, shared channel where a master

interfaces to multiple slaves (1:N topologies). Please see the ANT Message Protocol and Usage document

for further details on shared ANT channels.

4.2.3

ANT channel configuration

Unique to ANT is that the setup of each ANT channel is independent from all the other ANT channels in the

network, including other channels in the same node. This means that one ANT node can act as master on

one ANT channel while being a slave to another. Since there is no overall ‘network master’ present in ANT

networks, ANT allows you to configure and run each ANT channel solely based on the needs of the nodes

on that channel. Search- and pairing algorithms in ANT let you easily set up and shut down ANT channels

in an ad-hoc fashion. This gives you ultimate flexibility in adjusting ANT channel parameters like data rate

and latency versus power consumption. Moreover, you only make the network as complex as it needs to

be at any given time. In order for two ANT nodes to set up an ANT channel, they must share a common

channel configuration and channel ID. The necessary configuration parameters are summarized in Table

3. on page 16.

Master

Slave

Tch

Tch

Tch

time

time

Forward

direction

Reverse

direction

Channel time slot

(Always)

(Optional)