Can you recommend a Nordic device for me which supports BLE and sub-1 GHz RF?

[Nordicfan123]

Hi, basically I want to use the sub-1 GHz RF to implement time sync, does Nordic have such a product that supports concurrent BLE and sub-1 GHz RF?(maybe an SoC)

[AmbystomaLabs]

No they don’t. I don’t believe anyone has an SoC that does that. There are plenty of bits to RF style solutions (eg, Analog Devices Inc.) that can easily accommodate this but they will use a lot of power and consume a lot of board space. Plus it will be difficult to get a BLE software stack that you can use.

There are examples for time sync using BLE, perhaps you should consider that. Or, are you trying to sync with one of the low frequency broadcast time services?

[Nordicfan123]

Thank you for your help, but I don't think BLE can achieve micro-sec level time sync. I prefer to use RF frequency lower than 1GHz to do time sync.

[AmbystomaLabs]

The BLE data rate can accommodate usec sync but you are correct that with the random 10msec backoff in the standard this would be hard to achieve. Assuming the backoff has a uniform distribution then averaging sync times should get you quickly to a 1 msec time sync.

Not sure what you are going to do with usec accuracy though. The RTC on the nRF has only 1/32768 sec resolution and normally one would be loathe to run the 32MHz clock all the time due to the power consumption. Also at 10 ppm you will need to time sync frequently just to stay close to your goal of usec accuracy. 

[AmbystomaLabs]

Here is the link to Nordic's time sync solution.  They show 200nsec sync capability in code that can coexist with BLE.

devzone.nordicsemi.com/.../wireless-timer-synchronization-among-nrf5-devices

[lmouelo]

hello ambystomalabs do you know a way to synchronize mutliple peripheral device just with ble, without RADIO ? 

[AmbystomaLabs]

Not sure I understand your question.  BLE uses the 2.4GHz transceiver (ie, radio, modem, etc.) on the nRF.

If you are just using BLE to do time sync follow the Nordic method. There is normally one master in a time sync scenario. So just repeat the process to sync all your devices.