ANT Forum

Greetings my name is Samuel Escobar, I´m a biomedical engineer, working on a sensor network using ANT. I´m using two(2) NRF52 development kits with SDK 12 and the S212 (2.0) Softdevice. I need to transmit heart rate variability data from 30 different nodes to a central station, these nodes are configured as slaves ant the central hub acts as the master for the network. Every five seconds the master needs to cycle through all the different nodes and have them transfer the available data that each of them have gather over this period of time. I am new to the ANT protocol and with the reading I´ve done I figured that a appropriate approach to solve this problem is to have the master ask for data every five seconds and the slaves would then return a constant payload with the values that they gathered in that time, the unused payload would be set to zeros.I think the best way to do this is either using acknowledge or burst over the reverse channel every time the master asks for data. Sadly I cant find any examples that use two NRF52 DK boards, the ones i've found in the SDK and on the ANT webpage all use the ANT DK and one board for testing.

Can someone please point me in the right direction?, since embedded programming is not my main field of expertise I need to reference my codes with examples to fully understand what I have to do and how to do it, I understand how ANT works I just struggle with the implementation.

I'am open to any suggestions from you guys if you think there is a better way of implementing the network PLEASE let me know! I'll be thrilled to hear your opinions.

Best Regards and Thank you beforehand!

Samuel Escobar G      

Hi Samuel,

How many bytes do you need to push from each device every 5 seconds? This dictates whether we can handle this with just broadcast messages or if we need to get burst (or advanced burst) messaging involved.

If you're looking for examples, SDK12's Auto Shared Channel, Continuous Scan Mode, or the Advanced Burst messaging reference designs would be a good place to start.

Cheers,
Harrison      

Assuming a 150 bpm heart rate in five seconds there are 12.5 beats aprox 13, assuming the variable to sent is an uint8_t type then every five seconds I need to transfer 13bytes or two ANT payloads. So every five seconds the master device should receive 390bytes (13bytes per node * 30 nodes) do you think burst messaging is necessary for this low amount of data?

Thanks for answering my question btw!

     

Hi Samuel,

It might be simpler to use master channels at each node and broadcast at a quicker rate to a receiver running in continuous scan mode, rather than use a shared channel. So each node could broadcast at say 1 Hz, and then the scanning node would receive all of the data.

All of the examples also contain PCA10040 (the Nordic nRF52 DK board).