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I always think it's ME, not this time ;-)

Update : working now!

Reading the code from @Zakaton and @Gordon's response I added a characteristic.handle_cccd = 0x0038; statement.

      c.handle_cccd = 0x0038;
      return c.startNotifications();

Now the Notifications are coming through.

Device connected: A4:C1:38:4E:75:A0 public
Service: ebe0ccb0-7a0a-4b0c-8a1a-6ff2997da3a6
Characteristic: ebe0ccc1-7a0a-4b0c-8a1a-6ff2997da3a6
C: BluetoothRemoteGATTCharacteristic: {
  "uuid": "ebe0ccc1-7a0a-4b0c-8a1a-6ff2997da3a6",
  "handle_value": 54, "handle_decl": 53,
  "properties": { "broadcast": false, "read": true, "writeWithoutResponse": false, "write": false,
    "notify": true, "indicate": false, "authenticatedSignedWrites": false }
 }
Done!
temp: 2484  Hum: 53
temp: 2487  Hum: 53
temp: 2486  Hum: 53

Thanks for the inspiration.

BTW : My device is a Xiaomi BLE Thermometer type LYWSD03MMC

Hi,

I have the same error as the topic starter, not sure if my problem is related, I'm rather new to Espruino/BLE so it may be a "user error".

Here's my code, and the output it produces. It seems to run OK until the point when Notifications are enabled:

var d;
var out="";

function getData(){
  print("Getting data now");
  g.drawString("Getting data now",0,60);
    NRF.connect("A4:C1:38:4E:75:A0 public").then(function(device) {
      print("Device connected:",device.device.id);
      out=device.device.id;
      g.drawString(out,0,80);
      d=device;
      return d.getPrimaryService("EBE0CCB0-7A0A-4B0C-8A1A-6FF2997DA3A6");
    }).then(function(s) {
      out=s.uuid;
      g.drawString(out,0,105);
      if(s) { print("Service:",s.uuid); }
      else { print("S-error"); }
      return s.getCharacteristic("EBE0CCC1-7A0A-4B0C-8A1A-6FF2997DA3A6");
    }).then(function(c) {
      print("Characteristic:",c.uuid);
      print("C:",c);
      out=c.uuid;
      g.drawString(out,0,130);
      c.on('characteristicvaluechanged', function(event) {
        buf =E.toString(event.target.value.buffer);
        g.drawString(buf,0,155);
        print(buf);
        print(event.target.value.buffer);
        // For 26.0 degrees and 54% is like : new Uint8Array([47, 10, 54, 98, 10]).buffer
        b=event.target.value.buffer;
        temp=b[1]*256+b[0];
        hum=b[2];
        print("temp:",temp, " Hum:",hum);
      }); // c.on
      return c.startNotifications();
    }).then(function() {
    console.log("Done!");

  });
} // end getData function



setWatch(function(){
  print("Bangle setwatch on TOP button activated");
  g.clear();
  g.setFont("Vector",15);
  getData();
},BTN ,{ repeat:true,debounce:25 }
);

/*
WEBIDE OUTPUT

                 _
|  __|___ ___ ___ _ _|_|___ ___
|  __|_ -| . |  _| | | |   | . |
|____|___|  _|_| |___|_|_|_|___|
         |_| espruino.com
 2v06 (c) 2019 G.Williams
>
Bangle setwatch on TOP button activated
Getting data now
Device connected: A4:C1:38:4E:75:A0 public
Service: ebe0ccb0-7a0a-4b0c-8a1a-6ff2997da3a6
Characteristic: ebe0ccc1-7a0a-4b0c-8a1a-6ff2997da3a6
C: BluetoothRemoteGATTCharacteristic: {
  "uuid": "ebe0ccc1-7a0a-4b0c-8a1a-6ff2997da3a6",
  "handle_value": 54, "handle_decl": 53,
  "properties": { "broadcast": false, "read": true, "writeWithoutResponse": false, "write": false,
    "notify": true, "indicate": false, "authenticatedSignedWrites": false }
 }
Uncaught Error: Unhandled promise rejection: CCCD Handle not found
> 

*/

The NrfConnect output for the Notification is below.

I know the handle for the notification is 0x0038. When I connect to the device using RPI-gatttool using this handle it starts Notifications immediately.:

pi@raspberrypi3:~/Mydata/python/Xiaomi $ gatttool -b a4:c1:38:4e:75:a0 --char-write-req --handle='0x0038' --value="0100" --listen
Characteristic value was written successfully
Notification handle = 0x0036 value: c5 09 3a 4e 0a 
Notification handle = 0x0036 value: c4 09 39 4e 0a 

Do I need to specify this handle specifically before using startNotifcations, and if so, how do I do that?

Any help is welcome.

Thanks for the extensive explanation, sounds like a perfect addition for the reference. It's clear for me now.

Coming from other languages it feels "natural" to start with an "open" command, so that's the reason why I chose Storagefile in the 1st place.

This says it all!

Normal Storage functions are what I'd recommend you use for basically everything unless you intend to append textual data (eg a log file). They're much more efficient to write and read.

When I started using Espruino a few weeks ago, I was "fresh" re. Espruino. I found the extensive description really confusing. So I just picked one.

Now being a somewhat "less fresh" user I still wonder why there are 2 different file types. I read and reread the documentation, and still have no idea why the differences. It's probably me .....

Just making sure, my posts were not meant as a gripe, but an attempt to add to the discusion that @MaBe kicked of.

Tested my code once more to verify that both news.txt and news.txt\1 are recognised.
IT DOES NOT :O

var Storage = require("Storage");
l=Storage.list();
print(l);
function exists(name){
  return Boolean(Storage.open(name,"r").addr);
}
print(exists("news.txt"));
print(exists("news.txt\1"));
print(exists("nonews.txt"));
print(exists("ABC.txt"));

Output is:

[
"news.txt\1",
"weath0.txt\1",
"weath1.txt\1",
"stocks.txt\1",
"messages.txt\1",
"ABC.txt"
]
true
false
false
false

The mix of the 2 storage versions does not feel like a blessing anymore :)

When I check for files without an added chunk number (f.i. file ABC.txt) it is recognised perfectly with your code, output is:

[
"news.txt\1",
"weath0.txt\1",
"weath1.txt\1",
"stocks.txt\1",
"messages.txt\1",
"ABC.txt"
]
exists

As @fanoush explained there are 2 methods to store a file, I happened to use the files with the added chunk number.

Fair enough @MaBe but news.txt\1 is not recognised either.

s = require('Storage');
print(s.list());
filename = 'news.txt\1';
if (s.read(filename)!==undefined) {
  print("exists");
} else {
  print("does not exists");
}

Output is:

[
"news.txt\1",
"weath0.txt\1",
"weath1.txt\1",
"stocks.txt\1",
"messages.txt\1"
]
does not exists

OK, thanks, but all of my files have a .txt extension, and those are not recognised by your code :(

s = require('Storage');

print(s.list());

filename = 'news.txt';
if (s.read(filename)!==undefined) {
  print("exists");
} else {
  print("does not exists");
}

Output is:

[
"news.txt\1",
"weath0.txt\1",
"weath1.txt\1",
"stocks.txt\1",
"messages.txt\1"
]
does not exists

This works for me. It's based on the fact that addr is zero when a file does not exist. When a file exists addr is not zero but points to an address in Storage.

var Storage = require("Storage");

l=Storage.list();
print(l);

function exists(name){
  return Boolean(Storage.open(name,"r").addr);
}

print(exists("news.txt"));
print(exists("nonews.txt"));

The output is:

[
"news.txt\1",
"weath0.txt\1",
"weath1.txt\1",
"stocks.txt\1",
"messages.txt\1"
]
true
false

Great, I was just looking for some "file exists" code ;-)

The suggestions work OK for filenames without extension like "ABC". But I want to check for file "news.txt" and all variants report "false/missing".

This is my code

s = require('Storage');
file = { name : 'news.txt', exist : 0};

print(s.list());

// variant I
if (s.list().find(e => (e == file.name))) {
      file.exist = 1;
      console.log("I",file.name,"exists");
} else {
      file.exist = 1;
      console.log("I",file.name,"is missing ");
}
// variant II
if (s.read(file.name)) {
      file.exist = 1;
      console.log("II",file.name,"exists");
} else {
      file.exist = 1;
      console.log("II",file.name,"is missing ");
}

// variant III
print("III",s.list(/^file.name/));

// variant IV
print("IV",s.read(file.name)!==undefined);

// variant V
print("V",s.read(file.name));

Output is
`

[
"news.txt\1",
"weath0.txt\1",
"weath1.txt\1",
"stocks.txt\1",
"messages.txt\1",
"ABC",
"news"
]
I news.txt is missing
II news.txt is missing
III [ ]
IV false
V undefined

`

This is a working example I have come up with with your help, maybe it's of any use to others.

/*

Example of an Espruino Object that fires an event when the button on pin D17 is pressed.

*/

var P8 = {
  init : function(){
    setWatch(function(){
      P8.emit("button","D17");
    },D17 ,{ repeat:true,debounce:25 }
    );
  }
}; // end of P8 Object

// ============================= test of P8 object  ===============

P8.init();


P8.on('button', function(btn){ print("Button",btn, "press detected");});

Output of the script when the button is pressed:
Button D17 press detected

In this example the init function needs to be called at start of the main script. Not sure if there is a way to move this init into the Object, but this works for me.

BTW I had to reboot the Bangle when I wanted to reconnect it to WebIDE. Without rebooting is did not show up in the WebBluetooth devices of the WebIde.

And I mad sure it was not still connected to NrfConnect :-)

I tried the script on my Bangle:

• uploaded the script to the Bangle using WebIDE
  
• disconnected the Bangle from the WebIDE
  
• Using NrfConnect on iPhone reveals the Bangle, connected to it, and it shows the advertised services. Writing to 78290002..... works OK.
  
• To make sure I disconnected the Bangle from NrfConnect, and reconnected. The data I had written was displayed as I sent it. I GUESS this means that the data is written to the Bangle succesfully.
  
  

Maybe this helps?

Thanks for the "nudge", DONE!

Thanks for the nice example, would have saved many hours of my life ;-)

My apologies for being thick, but the example on Github will automagically appear in the Espruino Reference, right?

@gordon. YES, a simple example like in my previous post would have helped me getting this working. And YES, adding such an example to the doc for on/emit is the perfect place.

Thanks.

Based on the tip from @d3nd3-o0 I changed the example in message #1 to:

var eventEmitter = new Object();

//Create an event handler:
var myEventHandler = function () {
  console.log('I hear a scream!');
};

//Assign the event handler to an event:
eventEmitter.on('scream', myEventHandler);

//Fire the 'scream' event:
eventEmitter.emit('scream');

The result:
I hear a scream!

So that works!

So, there is no need in Espruino to require an events module, instead you just create an object, and use that as event emitter.

Thanks to @d3nd3-o0 for guiding me in the right direction!

Hi Marck,

Yes, I saw the object class with emit and on in the dock, realised that this was what I needed, but had no idea how to setup the object. I'm an Arduino guy, so this object stuff is new to me. So for Espruino beginners an working example really helps.

Thanks for the tip, why didn’t I think of that.

Have been searching the doc and forum for some clues how to do, but found nothing. Would be great for others if a simple example is added to the doc, which is by the way excellent.

Will try to make a working example today and post it here.

Cheers.

Hi,

I would like to create my own event handlers similar like the Bangle event handlers, f.i. the "step" handler.

Bangle.on('step', function(up) {
  print("step was made");
});

Tried this example from https://www.w3schools.com/nodejs/nodejs_events.asp

var events = require('events');
var eventEmitter = new events.EventEmitter();

//Create an event handler:
var myEventHandler = function () {
  console.log('I hear a scream!');
};

//Assign the event handler to an event:
eventEmitter.on('scream', myEventHandler);

//Fire the 'scream' event:
eventEmitter.emit('scream');

But this results in the error:

I read in the Espruino documentation here http://www.espruino.com/Reference#l_Object_emit about Object.emit and Object.on but can not find any reference or example on how to setup an eventEmitter in Espruino.

I'm rather new to Espruino/Javascript so maybe there's an obvious answer. Can someone point me in the right direction?

Yes, in this case it seems it's coming from node coming from the Espruino Hub on Arduino.

But it's not PC-only, as my selfcoded BLE-peripheral on an ESP32 has the unhandled promise.... too :-(

And the Bangle code from post #4 has no "code" at all, it's just a httprequest, so thta's not it either.

BTW Espruino code on a bare NRF52832 (version 1V97) i.c.w. the Espruino Hub also has the same error.

Beats me!

As an intermezzo I tried the Bangle.js App Loader from https://github.com/espruino/BangleApps.

Wanted to use it as a "simple" file uploader, but so far I can see the current code does not support that.

As an experiment I copied the cmdInstallApp function, slashed it, and created:

function cmdUploadFile(fileName, deviceAddress) {
    bangleSend(fileName, deviceAddress).then(() => process.exit(0));
}

When I executed it I got the dreaded 'Unhandled Prmise Rejection`, there's no escaping it ;-)

iMac19-9:bin gerard$ node apploadergwr.js upload heartOnScreen.js f3-2c-dc-06-01-95
Initialising Notifications
<snip>
UART: Discovering...
UART: Found device:  f3-2c-dc-06-01-95 Bangle.js 0195
UART: Connecting to f3-2c-dc-06-01-95
UART: BT> Connecting
UART: BT> Connected
UART: Disconnected
(node:79575) UnhandledPromiseRejectionWarning: Disconnected but not complete
(node:79575) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)
(node:79575) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

Not sure if this error message is interesting for you, but here it is.

The Bluetooth.println("OK") looks like a good solution, provided the \x10 does not suppress it.

Added a try and except around the code for connection, so that connection errors are trapped in the code, that works OK. Is the basis for adding a retry mechanism.