We are contemplating an application of the DA14695 device as a WiRa ranging device to supplement the Google/Apple Exposure Notification (GAEN) service. Currently the GAEN service attempts to measure distance between two smartphone users based on Bluetooth LE signal attenuation (Tx Pwr - RSSI) of Advertising Packets. The errors inherent in this approach are well known. Small WiRa-capable devices, attached to test phones, should be useful in characterizing these errors with the current installed base of smartphones, and to guide research for future phone technology. Also, the WiRa-capable devices could be useful by themselves without phones even now in many group settings such as workplaces, schools and nursing facilities. (The Bluetooth SIG has just announced a Working Group on the use of embedded devices for contact tracing and exposure notification.)
All of this depends on inexpensive (both in cost and power budget) devices that can be widely distributed, both as wearable and fixed devices. So several questions arise:
- Using the DA14695, your SDK and sample code for WiRa, what's the minimal HW configuration for such a device (ignoring power input and antenna issues for the moment)? Mainly the DA14695 and some external Flash memory? What size?
- What are the memory requirements of your sample WiRa app.
- Can the DA14695-00HQDEVKT-U USB dev board (without the J-Link HW) be considered to be a suitable "reference design"?
- What info can you provide for the additional power consumption to support WiRa (radio transmission, plus computations). Is this amount tunable to balance ranging vs. energy consumed?
- Based on an earlier question in this forum, I'm assuming a DA14695 is either an Initiator or Responder in a WiRa ranging interaction, but that it can switch roles between interactions. Correct? What's the latency for such a switch? Energy cost?
- I'm also assuming that the WiRa functionality piggybacks/interleaves with normal Bluetooth LE traffic. Does it require a Connection, or are Advertising and Response packets sufficient.
- A way to harvest data from the device is necessary. I assume normal Central/Peripheral Bluetooth LE connections can be used simultaneously with the WiRa funtionality (between the device in question and some third device). Does the HW and your SDK support Bluetooth Mesh at the same time as WiRa?
Thanks in advance for any and all anwers to the above questions,
(participating in a number of COVID-19 efforts, e.g., Covid-Watch.org and LFPH (Linux Foundation Public Health working group)