BLE scan and advertising parallel?

[espruino-discuss]

Posted at 2021-11-17 by kreativmonkey

Is it possible to scan and advertise at the same time? I would like to do a setup with 3 beacon. Each beacon should scan for the other two beacons and save the current rssi. In the next Advertising package the beacon should send the last received rssi from the other two beacons. I'm new on programming with JavaScript. My current Codebase shows this:

const be = {
      name: "BLE-Beacon B", // The name of the device
      showName: true, // include full name, or nothing
      discoverable: true, // general discoverable, or limited - default is limited
      connectable: true, // whether device is connectable - default is true      
      scannable : false, // whether device can be scanned for scan response packets - default is true
      interval: 300, // Advertising interval in msec, between 20 and 10000 (default is 375ms)
      manufacturer: 0x0590, // IF sending manufacturer data, this is the manufacturer ID
    };

var deviceA = 0;
var deviceB = 0;
var deviceC = 0;

// Start scanning
started = true;
logging = true;

// scanning for the devices
function scanDevice(d) {  
  let modified = false;
    
  // witch device is scanned
  // change the value
  switch (d.name) {
      case "BLE-Beacon A":
          modified = (deviceA !== d.rssi);
          deviceA = d.rssi;
          break;
      case "BLE-Beacon B":
          modified = (deviceB !== d.rssi);
          deviceB = d.rssi;
          break;
      case "BLE-Beacon C":
          modified = (deviceC !== d.rssi);
          deviceC = d.rssi;
          break;
  }
  
  // if value was modified setAdvertising to new Value
  if(modified){
    NRF.setAdvertising({
      0x180F: [deviceA]
      }, {
            name: be.name,
            manufacturer: be.manufacturer,
            interval: be.interval,
            manufacturerData: ["A", deviceA, "B", deviceB, "C", deviceC]
        });
  } else {
    console.log("nothing modified");
  }
  
}

// Initiales Scanning
NRF.setScan(scanDevice, {filters: [{namePrefix:"BLE-Locate"}] });

// Initiales Advertising
NRF.setAdvertising({}, {
            name: be.name,
            manufacturer: be.manufacturer,
            interval: be.interval,
            manufacturerData: ["A", deviceA, "B", deviceB, "C", deviceC]
        });

// Watch if BTN was pressed
setWatch(function(){
 console. log("Device: " + be.name);
  
  if (started) {
    NRF.setScan();
    started = false;
    console.log("Stop Scanning");
  } else {
    NRF.setScan(scanDevice, {filters: [{namePrefix:"BLE-Locate"}] });
    started = true;
    console.log("Start Scanning");
  }
}, BTN, {edge:"rising", repeat:1, debounce:20});

[espruino-discuss]

Posted at 2021-11-17 by @gfwilliams

Hi - yes, BLE broadcast while scanning should 'just work' - however Espruino will only broadcast via BLE when you're disconnected from it, so that might be the issue you're hitting?

---

Posted at 2021-11-17 by kreativmonkey

@gfwilliams yes that off course fixed the issue i have ;-). I've changed my code over the day it works like aspactad.

let started = false;  // if scanning is startet
var intervalLed;
var selfid = NRF.getAddress().substr(12,5).replace(':',''); // get the last 5 digits of ble mac as id
var scanIds = [ "5c5b", "69f0", "6d31" ];  // list of devices to scan for
var data = new Uint8Array(scanIds.length); // define data as zero

// Default ble settings
const be = {
      name: "BLE "+ selfid, // The name of the device
      showName: true, // include full name, or nothing
      discoverable: true, // general discoverable, or limited - default is limited
      connectable: true, // whether device is connectable - default is true      
      scannable : true, // whether device can be scanned for scan response packets - default is true
      interval: 375, // Advertising interval in msec, between 20 and 10000 (default is 375ms)
      manufacturer: 0x0590, // IF sending manufacturer data, this is the manufacturer ID
    };

// update Advertising by the current received rssi
function updateAdvertising(device) {
  // our data - all 0 for nothing, 
  // or RSSI + 6 bytes address
  var id = device.id.substr(12, 5).replace(':','');

  if (!scanIds.includes(id)) return;

  data[scanIds.indexOf(id)] = device.rssi * -1; // converte to positive integer

  NRF.setAdvertising({}, {
    showName: false,
    connectable: false,
    scannable: false,
    interval: 100,
    manufacturer: be.manufacturer,
    manufacturerData: data
  });
  
  console.log("Found Device: " + id);
}

function setDefault() {
  // Initiale Advertising
  NRF.setAdvertising({}, {
    name: be.name,
    showName: be.showName,
    discoverable: be.discoverable,
    connactable: be.connectable,
    scannable: be.scannable,
    interval: be.interval,
    manufacturer: be.manufacturer,
    manufacturerData: data
  });
}

Pin.prototype.flash = function(period) { 
  var pin = this;
  digitalWrite(pin, true);
  setTimeout(function() {
    digitalWrite(pin, false);
  }, 100);
};

// Setting up defaults
setDefault();

// Watch if BTN was pressed
setWatch(function(){
  console.log("Device: " + be.name);
  
  if (started) {
    console.log("Stop Scanning");
    NRF.setScan();  // Stop scanning on BLE devices
    clearInterval(intervalLed); // Stop Led from blinking
    started = false; // switch device status
    LED1.flash(); // Show stop with red LED
    setDefault();
  } else {
    console.log("Start Scanning");
    started = true;
    LED2.flash();  // Show start with green LED
    NRF.setScan(updateAdvertising); // Start scanning for BLE devices
    intervalLed = setInterval('LED2.flash();', 10000); // Flash the green led to visualise scanning mode
  }
}, BTN, {edge:"rising", repeat:1, debounce:20});

Now i have two new problems. First of all, after starting and stopping, i can't connect to the Puck-js scince i'm pull out the battery and plug it in again.

~~The second problem is the advertising interval. If i change the interval to somthing under 100ms i don't reseive any packages from the device. ~~

[Edit] Answere for the second Question:
NOTE: Non-connectable advertising can't have an advertising interval less than 100ms according to the BLE spec.

---

Posted at 2021-11-18 by @gfwilliams

, i can't connect to the Puck-js

Looks like you set connectable: false, but then there's a typo when you try and set it to true again connactable: be.connectable,