Puck Controlling Puck - Troubleshooting Help

[espruino-discuss]

Posted at 2021-05-18 by Kymvaris

I am trying to implement the code in the example in this link: https://www.espruino.com/Puck.js+Controlling+Other+Pucks

I have two Puck.js v1.0 running firmware 2v09. I flashed one with the "peripheral" code and saved it to flash before disconnecting from the Web IDE and power-cycling the Puck. I flashed the other with the "central" code with a few added debug statements in the catch blocks to print out the error.

When I press the button on the central puck, my the LED flashes red to indicate error and the error is printed to the console: BLE error 0x11 (BUSY). After that, any button presses just report the error "No device found matching filters" until I power-cycle the peripheral Puck. I assume my central puck is successfully connecting but not disconnecting when the error is caught (even though I call the disconnect()) function. This leaves the peripheral Puck in an odd state that can only be fixed with a power-cycle.

My question is twofold:

1. Where am I going wrong with the sample code (in the link above) because my peripheral Puck is always busy?
2. How can I disconnect cleanly on error so I don't have to power-cycle my peripheral Puck every time?

Since I modified the example code (to add debug statements in the catch() blocks), here is my code:

// Are we busy?
var busy = false;

// The device, if we're connected
var connected = false;

// The 'tx' characteristic, if connected
var txCharacteristic = false;

// Function to call 'toggle' on the other Puck
function sendToggle() {
  if (!busy) {
    busy = true;
    if (!connected) {
      NRF.requestDevice({ filters: [{ name: 'Puck.js ....' }] }).then(function(device) {
        return device.gatt.connect();
      }).then(function(d) {
        connected = d;
        return d.getPrimaryService("6e400001-b5a3-f393-e0a9-e50e24dcca9e");
      }).then(function(s) {
        return s.getCharacteristic("6e400002-b5a3-f393-e0a9-e50e24dcca9e");
      }).then(function(c) {
        txCharacteristic = c;
        busy = false;
        // Now actually send the toggle command
        sendToggle();
      }).catch(function(e) {  
        console.log("error: ", e);
        connected=false;
        digitalPulse(LED1, 1, 500); // light red if we had a problem
        busy = false;
        if (connected) connected.disconnect();
      });
    } else {
      txCharacteristic.writeValue("toggle()\n").then(function() {
        digitalPulse(LED2, 1, 500); // light green to show it worked
        busy = false;
      }).catch(function(e) {
        console.log("error: ", e);
        digitalPulse(LED1, 1, 500); // light red if we had a problem
        busy = false;
        if (connected) connected.disconnect();
      });
    }
  }
}

// Call sendToggle when the button is pressed
setWatch(sendToggle, BTN, { edge:"rising", debounce:50, repeat: true });

As additional information, the example code in the following documentation articles also fails with a BLE error 0x11 (BUSY) message.

1. https://www.espruino.com/Reference#l_NRF_requestDevice
2. https://www.espruino.com/Reference#t_l_NRF_connect

The sample code in the documentation here: https://www.espruino.com/Reference#t_BluetoothDevice does execute without error. This is leading me to believe that my two Pucks can connect to each other but when I try to use the UART service to send commands, the BLE error 0x11 (BUSY) error is thrown.

[gfwilliams]

Posted at 2021-05-19 by @gfwilliams

Hi - this is an odd one. I get this too. It seems like you're doing everything right on the code front.

Please could you try:

      NRF.requestDevice({ filters: [{ name: 'Puck.js ....' }] }).then(function(device) {
        return device.gatt.connect();
      }).then(function(d) {
        connected = d;
        return new Promise(r => setTimeout(r,500)); //< ---------- added this delay
      }).then(function() {
        return connected.getPrimaryService("6e400001-b5a3-f393-e0a9-e50e24dcca9e");
      }).then(function(s) {
        return s.getCharacteristic("6e400002-b5a3-f393-e0a9-e50e24dcca9e");
      }).then(function(c) {
     ...

That's what worked well for me...

I'm a bit busy today but I just filed an issue for this at espruino/Espruino#2008 and I'll try and get it fixed properly as soon as I can.

[espruino-discuss]

Posted at 2021-05-19 by Kymvaris

Gordon -

Works like a champ with the added delay. Here's the full code just for anybody looking to see it all together:

// Are we busy?
var busy = false;

// The device, if we're connected
var connected = false;

// The 'tx' characteristic, if connected
var txCharacteristic = false;

// Function to call 'toggle' on the other Puck
function sendToggle() {
  if (!busy) {
    busy = true;
    if (!connected) {
      NRF.requestDevice({ filters: [{ name: 'Puck.js ....' }] }).then(function(device) {
        return device.gatt.connect();
      }).then(function(d) {
        connected = d;
        console.log("Connected");
        return new Promise(r => setTimeout(r,500));
      }).then(function() {
        return connected.getPrimaryService("6e400001-b5a3-f393-e0a9-e50e24dcca9e");
      }).then(function(s) {
        return s.getCharacteristic("6e400002-b5a3-f393-e0a9-e50e24dcca9e");
      }).then(function(c) {
        txCharacteristic = c;
        busy = false;
        // Now actually send the toggle command
        sendToggle();
      }).catch(function(e) {
        console.log("error: ", e);
        connected=false;
        digitalPulse(LED1, 1, 500); // light red if we had a problem
        busy = false;
        if (connected) connected.disconnect();
      });
    } else {
      txCharacteristic.writeValue("toggle()\n").then(function() {
        digitalPulse(LED2, 1, 500); // light green to show it worked
        busy = false;
      }).catch(function(e) {
        console.log("error: ", e);
        digitalPulse(LED1, 1, 500); // light red if we had a problem
        busy = false;
        if (connected) connected.disconnect();
      });
    }
  }
}

// Call sendToggle when the button is pressed
setWatch(sendToggle, BTN, { edge:"rising", debounce:50, repeat: true });

Thanks for the help!

[gfwilliams]

Posted at 2021-05-19 by @gfwilliams

Great - thanks for letting me know! I'll try and get a fix in soon - I'm not sure how that crept into 2v09

[gfwilliams]

Posted at 2021-06-16 by @gfwilliams

I'm just looking into this, and with latest firmwares I can't reproduce it running your original code.

Any hints as to how I might reproduce it here?

[gfwilliams]

Posted at 2021-06-18 by @gfwilliams

Ok, I figured it out (I think). This is due to negotiation of a higher MTU since this was added in Espruino 2v09.

I think if you're connecting to a device with an older firmware you can connect just fine. It's when you connect between two devices with 2v09+ firmware that you have the issue. Follow this on the GitHub issue.