Proximity detection

[dfbdfb]

Hi Nordic team,

I am working on a project with one central and several peripheral BLE devices. The peripherals are moving randomly, is it possible to detect the event when certain two/multiple devices get close (like <10 cm)?

I have searched around and saw the Nordic Distance Toolbox, it seems to be in larger scale. I don't know if it can work at centimeter level. I also checked NFC but I feel it is also not suitable. 

Thanks in advance

[Kenneth]

Yes and no. If your requirement is an accurate 10cm range, the answer is no. If you mean that is need to be close by (e.g. 0-50cm range), then you can use the RSSI value, monitor the RSSI value over some time to estimate with a high degree of certainty that the peer is very close (e.g. 0-50cm range). Something like this should work quite reliably, but it's not possible to state exactly 10cm no.

Kenneth

[dfbdfb]

Thanks for your reply. 

If I don't need to know the accurate distance, I only want to know if two objects have touched each other, is it possible to be done by BLE? I feel it is similar to NFC or RFID card reading.

[Kenneth]

Sorry, but I don't see we have a solution for this. Though you can attach any kind of sensor to the I2C or SPI serial interface, so if you find any sensor that does this for you then likely you can use it. I notice you are mentioning NFC, but that will only work with an NFC reader (while the nRF52 is an NFC tag).

Best regards,
Kenneth