Puck stops working/broadcasting once it's disconnected from IDE… is it my code?

[espruino-discuss]

Posted at 2025-01-25 by remy

I've been trying to make a simple moisture sensor broadcasting using bthome. Moisture isn't a valid type for the BTHome library, so I'm sending the bytes directly.

Upon the update function being called (every 2 seconds), the LED flashes. Whilst the puck is connected (over BT) to the Espruino IDE the puck appears to work - flashing the LED.

As soon as I disconnect the browser, the LED stops flashing, and I can no longer connect to the puck. Only a full reset (re-insert battery with BTN1 held for 10 seconds) allows me to reconnect.

This is the output from process.env:

{
  VERSION: "2v25",
  GIT_COMMIT: "1dccab89f" ,
  BOARD: "PUCKJS",
  RAM: 65536, FLASH: 524288, HWVERSION: 1, STORAGE: 98304,
  SERIAL: "b84bfae7-0dfc27f4" ,
  CONSOLE: "Bluetooth",
  MODULES: "Storage, heatshrink, neopixel",
  EXPTR: 3785205h, 
}

I've got my moisture sensor wired to GND, 3V and AOUT (from moisture) to D28 on the Puck.

This is my code, but I can't see anything that might cause any issue:

function onInit() {
  NRF.setTxPower(4);
}

function getMoistureValue() {
  return analogRead(D28);
}

function update() {
  NRF.setAdvertising(
    [
      0x02,
      0x01,
      0x06, // Flags
      0x11,
      0x16, // Length and Service Data
      0x18,
      0x1e, // UUID for BTHome
      0x40, // BTHome device type (generic)
      0x2f,
      0x01, // Moisture sensor type (0x2F), length (1 byte)
      Math.round(getMoistureValue() * 100), // Moisture value (scaled to 0-100%)
      0x02,
      0x01, // Battery sensor type (0x02), length (1 byte)
      E.getBattery(), // Battery percentage
      0x01,
      0x02, // Temperature sensor type (0x01), length (2 bytes)
      (E.getTemperature() * 100) & 0xff, // Temperature low byte
      ((E.getTemperature() * 100) >> 8) & 0xff, // Temperature high byte
    ],
    {
      name: 'Moisture',
      // interval: buttonState != 'none' ? 20 : 2000, // fast when we have a button press, slow otherwise
      // not being connectable/scannable saves power (but you'll need to reboot to connect again with the IDE!)
      //connectable : false, scannable : false,
    }
  );

  digitalPulse(LED1, 1, 1); // show activity
}

// When a button is pressed, update advertising with the event
setWatch(
  function () {
    update();
  },
  BTN,
  { edge: 'falling', repeat: true }
);

// Update advertising now
update();

setInterval(() => {
  update();
}, 2000);

Any ideas what this might be - or equally is there any way I can debug the device in any other way?

[espruino-discuss]

Posted at 2025-01-26 by @allObjects

@remy

I suggest that you put this part of the code

// Update advertising now
update();
setInterval(() => {
  update();
}, 2000);

into the onInit() function at the bottom.

Then when save() the code with this command in the console of the Espruino IDE, the IDE will save to code into the flash and run the onInit();. Puck will also run onInit(); on every power off-on cycle. Take a look at simple explanation how to save code that espruino run on start? - mainly Post #8.

Doing so gives a different grieve when connected and uploading code. The uploaded code will not start... because nobody calls it or there is no power cycle. For that reason, I put in all my code during development time this as the last line of code:

setTimeout(onInit,999); // during dev only - comment line BEFORE save()

---

Posted at 2025-01-27 by @gfwilliams

I think it's probably complaining about the data not being valid (since the nRF52 checks the data looks ok before transmitting - I think maybe the length is wrong in array index 5?), but you can't see because you're disconnected. Maybe try adding whenConnected:true after name which will allow it to advertise while you're connected and which might then allow you to see the error.

Personally, I think this is probably not a good idea - you want to save E.getTemperature()*100 to a variable, because it could change between the two readings:

(E.getTemperature() * 100) & 0xff, // Temperature low byte
      ((E.getTemperature() * 100) >> 8) & 0xff, // Temperature high byte

The easiest option would be just to add moisture to BTHome though? If you just put exports={} at the top of your code, paste in this: https://github.com/espruino/EspruinoDocs/blob/master/modules/BTHome.js

... and then do NRF.setAdvertising(exports.getAdvertisement([... you could make the changes you need very easily.

Or at the very least use Espruino to package up the BTHome data for you so you don't have to worry about getting the lengths right:

NRF.setAdvertising({
    0xFCD2 : [
      0x40, // BTHome device type (generic)
      0x2f,
      0x01, // Moisture sensor type (0x2F), length (1 byte)
      Math.round(getMoistureValue() * 100), // Moisture value (scaled to 0-100%)
     ....
  ]
}, {
      name: 'Moisture'
});

---

Posted at 2025-01-27 by remy

Cheers, I had suspected it was my packet, because I had it working when I using the require('BTHome'). I only just found the source for the BTHome module (and didn't even think to find it on github!), so I figured the same, inlining the module and adding moisture (and probably removing the unused types) would be the sensible approach.

I temporarily got around the BTHome issue by using the module, and sending the moisture under humidity, then renaming the entity at my HA instance.

Long story short - yep, Gordon is right, for anyone thinking of doing this here's the updated code attached (there was also a fairly big bug in my code that chews through the battery since the moisture probe sensor is always on).

---

Attachments:

• moisture.js

---

Posted at 2025-01-28 by @gfwilliams

Thanks! I believe I have just added moisture to the BTHome library - please can you try now and see if it works? I made some changes to reduce code size too.

I also added the ability to supply custom data as an array (https://www.espruino.com/BTHome#custom-data) so hopefully this won't happen again if someone needs to add something that the default library doesn't support.