Proximity Spotter

Demonstrates how to scan for nearby beacons and get information about spotted devices

Overview

The proximity spotter example scans for surrounding Bluetooth LE beacons. If any are detected, the application controlls the brightness of an LED on the device based on the RSSI of the received advertising packet.

Since scanning operations and the LED can consume significant amounts of power, the application uses the device's on-board accelerometer to detect when it is in motion. Scanning only occurs during a window of time after movement is detected. At other times, the device enters a low-power idle mode.

The proximity spotter application

Source Code

The source code for this app is provided in the proximity-spotter directory of the blecon-oem-device-firmware repository: https://github.com/blecon/blecon-oem-device-firmware/tree/main/apps/proximity-spotter

Supported Devices

This code supports the following Zephyr board types:

• mkbnl02sn/nrf54l15/cpuapp- MOKO SMART L02S-BCN Smart Beacon

Configuration Options

Configurations for each board type is found in the configuration sub-directory.

Proximity Thresholds

• PROXIMITY_RSSI_THRESHOLD - Sets the minimum RSSI value for a device to register as a scan result. This setting allows the device to ignore weak signals from distant devices.

• PROXIMITY_RSSI_MIN_BRIGHTNESS , PROXIMITY_RSSI_MAX_BRIGHTNESS - Sets the mapping of RSSI value to minimum (off) and maximum LED brightness levels. RSSI values that lie outside of this range map to the minimum and maximum brightness levels. RSSI levels between these values are interpolated using an exponential function so that small changes in RSSI when the devices are nearby produce perceivable changes in brightness.

Motion Sensitivity

The MOTION_ACC_THRESHOLD constant in src/main.c can be adjusted to set the threshold for the device to detect motion (and activate scanning). Units are in m/s^2.

LED mapping

LED mappings are configured in the app.overlay file for the selected board under the chosen node. The blecon-led-proximity property must point to a PWM-capable LED node to display proximity to a nearby beacon.

The blecon-led-status property can be assigned to an LED device to configure the LED used to show Blecon status like whether the device is announcing its ID and connected to Blecon.

Blecon LED Status Library

To display Blecon connection status on LEDs, the BLECON_LED_LIB option must be enabled. For devices with limited memory, this library can be disabled to reduce the application's memory footprint.