• State Verified Answer
  • Replies 6 replies
  • Subscribers 71 subscribers
  • Views 3747 views
  • Users 0 members are here
Attachments (0)
Nordic Case Info
  • Case ID: 111340
Options
This post is older than 2 years and might not be relevant anymore
More Info: Consider searching for newer posts

Ranging of connectable device based on nRF51822

Keton

Hi,

I'm developing nRF51 proximity based device using nRF51822 that acts as BLE peripheral. It advertises continuously using connectable indirect mode. User has Android smartphone with dedicated application. When user comes closer to the device than some given distance (i.e. 2 meters) smartphone app should connect to it and exchange some data. Distance measurement is based on RSSI.

Problem is that in Android during BLE scan most phones report each device only once if it's using connectable advertisements. Only for beacons (non connectable, indirect slow advertisement) RSSI is reported for each advert. packet. I want to be able to measure RSSI of multiple advertising packets and be able to connect to the device.

What I've tried so far:

  1. searching Android documentation for a way to modify default behavior of BLE scanner. I've found it for iOS but not for Android.
  2. various modifications to Android scan process (i.e. starting BLE scan for 1s, aborting it and restarting after short delay) - this works for some devices but ranging data are very unreliable and I get very little advertising packets compared to beacon and continuous scan.
  3. change advertisement parameters of nRF51 to those used by SDK beacon example while keeping BLE services set up. Ranging works fine but during connection attempt board reboots.

Last idea I have is to set up nRF51 to advertise as 2 devices - beacon and connectable device at the same time. Is it possible and if yes could you point me to some example code / documentation of how to do it?

Alternatively - is there other way to achieve my goal - forcing Android to report given device multiple times in single BLE scan while retaining ability to connect to it?

Parents
  • 0

    Øyvind,

    Thanks for your answer.

    I've decided to try concurrent approach based on Github example. I've managed to compile the project under SDK10 and gcc 4.9.

    I'm afraid I don't understand exactly how it works. Could you provide barebones example of connectable service running along non-connectable time slot advertiser?

    My other questions are as follows:

    1. In order to compile this project I had to remove app_timer.c and softdevice_handler.c from my project because of duplicate declarations of SD_EVT_IRQHandler and SWI0_IRQ_Handler in advertiser code. My application uses app_timer a lot. Is there a way to use provided time slot advertiser library with app_timer? Also is it possible to use standard softdevice handler in order to use event handlers it generates (I have connectable service which has to receive ble events and for that I've used softdevice_ble_evt_handler_set())?

    2. Is there any way to pause time slot advertiser so it doesn't broadcast when user connects to the device via connectable advertising (non timeslot) part?

    3. Another issue is setting advertisement data for timeslot advertiser. Github readme mentions functions void btle_hci_adv_params_set(btle_cmd_param_le_write_advertising_parameters_t* adv_params) and void btle_hci_adv_data_set(btle_cmd_param_le_write_advertising_data_t* adv_data) but they are never used in the example code. Also time slot advertiser beacon doesn't advertise anything apart from appearance and name. Is this correct behavior?

    4. In order to compile the code I've had to define DEFAULT_DEVICE_ADDRESS in ts_controller.c. I reckon that modifying library code provided by Nordic isn't a recommended way of doing things. Is there any better solution? Specifically I'm thinking about deriving time slot advertiser address from BLE address hardcoded in each nRF51 chip but that would require further modifications to the library. Or maybe I'm missing something that should set DEFAULT_DEVICE_ADDRESS?

Reply
  • 0

    Øyvind,

    Thanks for your answer.

    I've decided to try concurrent approach based on Github example. I've managed to compile the project under SDK10 and gcc 4.9.

    I'm afraid I don't understand exactly how it works. Could you provide barebones example of connectable service running along non-connectable time slot advertiser?

    My other questions are as follows:

    1. In order to compile this project I had to remove app_timer.c and softdevice_handler.c from my project because of duplicate declarations of SD_EVT_IRQHandler and SWI0_IRQ_Handler in advertiser code. My application uses app_timer a lot. Is there a way to use provided time slot advertiser library with app_timer? Also is it possible to use standard softdevice handler in order to use event handlers it generates (I have connectable service which has to receive ble events and for that I've used softdevice_ble_evt_handler_set())?

    2. Is there any way to pause time slot advertiser so it doesn't broadcast when user connects to the device via connectable advertising (non timeslot) part?

    3. Another issue is setting advertisement data for timeslot advertiser. Github readme mentions functions void btle_hci_adv_params_set(btle_cmd_param_le_write_advertising_parameters_t* adv_params) and void btle_hci_adv_data_set(btle_cmd_param_le_write_advertising_data_t* adv_data) but they are never used in the example code. Also time slot advertiser beacon doesn't advertise anything apart from appearance and name. Is this correct behavior?

    4. In order to compile the code I've had to define DEFAULT_DEVICE_ADDRESS in ts_controller.c. I reckon that modifying library code provided by Nordic isn't a recommended way of doing things. Is there any better solution? Specifically I'm thinking about deriving time slot advertiser address from BLE address hardcoded in each nRF51 chip but that would require further modifications to the library. Or maybe I'm missing something that should set DEFAULT_DEVICE_ADDRESS?

Children
Related
Terms of service