ANT Forum

Hello,

is the 32.768kHz clock mandatory for ANT+ chips?
For the CC2571 8 channels?
For the nRF24AP2 8 channels?

Not very clear on datasheets...

Thanks in advance!      

It is mandatory in the C7, and optional (but recommended for lowest power consumption) in the AP2.      

Thanks a lot!

In our application, we would have the host microcontroller that wake up every period or event to turn on the RF transceiver (C7 or AP2) and transmit data, than set transceiver to the lowest power down mode (SLEEP or DEEP SLEEP).

Is it a viable architecture?

In this case, is the 32.768kHz crystal still mandatory for C7 (I guess it is needed only for accessory internal ANT timing, such as timeouts)?

Anyway, the AP2 chip seems very viable for our design: we can have just the 16MHz host crystal, fed to AP2 as well. No 32.768kHz. If we choose the CC2571, we need 3 crystals: 32MHz and 32.768kHz for C7, 16MHz for host microcontroller.

Any other hint?

Thanks in advance!      

The C7 does require the 32KHz crystal - the crystal is required for the ANT protocol to work.

ANT automatically wakes up every channel period and turns on the RF transceiver - the host microcontroller does not need to manage this. Your microcontroller does not need to wake up ANT; power state management is already a feature of the protocol. For more details on this, please refer to AN13 ANT Power States
http://www.thisisant.com/developer/resources/downloads/

     

Thanks for your reply.

Actually, we would like to have the host to be the.. "host", to have the complete control of RF operation. I know ANT transceivers can handle all timeouts and wake-ups, but for us is better to assign this duty to the host MCU, because it have to make a lot of other work (analog sampling, calculations, ...).

So, are there any issues to have the host to power on the ANT transceiver, program it (channels ID, ...), to send RF data and to power off?

Thanks!

     

What are you intending to use as the receiver? Is the receiver side also a power constrained device?
It is not possible to have your host MCU have full control over the RF operation with ANT - the ANT stack handles the RF activity. However, ANT was designed with ultra low power operation in mind (specially if both sides of the link are power constrained, i.e., coin cell batteries), and the control of the RF activity done in the ANT protocol stack is fully optimized for that. You do not need to worry about managing the power states of the radio as ANT already does that for you. And you do not need to worry about how to handle coexistence, how to get the receiver to synchronize with the transmitter, how to handle outages, etc, as ANT already implements that for you.