add a microbit scrolling text example

[danjenkins]

Let me know if you don't want this in this repo and rather it be a separate repo on the nimbleape org

Basic demo that allows you to write to a micro:bit's led service and have text scroll across the LED matrix on the micro:bit - its a standard service on the micro:bit runtime (microbit-dal)

It also adds support for disconnecting from the micro:bit which isn't in any of the other demos yet I think.

Let me know your thoughts - follows the same patterns as other demos - uses polymer but not the polymer web bluetooth components which hides things away....

I have submitted a CLA, waiting to hear back

[beaufortfrancois]

Thank you @danjenkins! 447 files is too big for GitHub to review this patch. Could you split your PR into 2 commits? One without bower_components and another one with bower_components.

Here's one nit I've noticed:
You could use gattserverdisconnected (featured in https://googlechrome.github.io/samples/web-bluetooth/device-disconnect.html) to know when device is actually disconnected.

[danjenkins]

Thanks @beaufortfrancois ! I'll do that! Sure, I forgot there was an event - why is a promise not returned from disconnect? Seems like it should be (talking spec now)

[beaufortfrancois]

disconnect() doesn't return a promise. See https://webbluetoothcg.github.io/web-bluetooth/#dom-bluetoothremotegattserver-disconnect and WebBluetoothCG/web-bluetooth#194

[jyasskin]

@danjenkins disconnect() doesn't return a promise because we can make it appear to happen instantaneously from the point of view of the page, and because a call to disconnect() from one page may not physically disconnect the device if other pages are still connected. If you want to be sure there's a physical disconnection, you have to ask the device to do it, which will then be reported by gattserverdisconnected. Does that cover what you wanted to use the Promise for?

[danjenkins]

Yeah that makes sense; it's just that when I was writing the code; I wrote it expecting a promise to be there - as it made sense for it to be there - your explanation makes sense but from a developer point of view; Calling disconnect and then having to listen for an event too is a shame - it would be cool if the it did return a promise that got resolved when the event is fired in that specific scenario

[jyasskin]

I guess I don't follow what you want to use the gattserverdisconnected event for. Calling disconnect() and then listening for it doesn't give you any extra information because it's fired by the call.

[beaufortfrancois]

@danjenkins Keep in mind that you would probably always want to use the gattserverdisconnected event because it would also be triggered if the device would go out of range / run out of battery / etc.
Moreover as soon as you call disconnect(), your BluetoothDevice is not connected anymore from a JS point of view and you can't do anything but reconnecting before interacting with services/characteristics.

[danjenkins]

I guess up until now I never listened for disconnect because it didn't exist... all sample apps should now encourage listening for disconnect as part of server connect sequence

[beaufortfrancois]

http://beaufortfrancois.github.io/sandbox/web-bluetooth/generator/ does ;)

[danjenkins]

SO MANY SITES!! @beaufortfrancois ! I'll try and tackle this PR in the coming days (currently away from home)

[beaufortfrancois]

:) For info, all URLs are gathered in https://developers.google.com/web/updates/2015/07/interact-with-ble-devices-on-the-web

[beaufortfrancois]

I've just received my BBC micro:bit device and it works smoothly on Android. Sadly, pairing process is not triggered on Chrome OS. I've filed a bug at https://bugs.chromium.org/p/chromium/issues/detail?id=629773 for this.

[danjenkins]

Did you turn off bluetooth pairing? https://github.com/nimbleape/microbit-led-service ?

By default the microbit wants proper pairing but thats not very BLE (think bb8) so you can turn it off - the BBC wanted protection etc for kids.

https://github.com/nimbleape/microbit-led-service/blob/master/config.json#L5

[beaufortfrancois]

I didn't notice the README file. Thanks!
My BBC micro:bit device hasn't been modified yet for this sample.

[danjenkins]

Ah! :) Yes; still good to know about the pairing issue on ChromeOS

[beaufortfrancois]

After changing my micro:bit device to more "opened" (not requiring pairing), I'm still having some issues. It looks like the LED service does contain only one characteristic - the led matrix state, not the led text one.

I can reproduce it with https://googlechrome.github.io/samples/web-bluetooth/discover-services-and-characteristics.html?optionalServices=e95dd91d-251d-470a-a062-fa1922dfa9a8,00001801-0000-1000-8000-00805f9b34fb,e95d93b0-251d-470a-a062-fa1922dfa9a8,0000180a-0000-1000-8000-00805f9b34fb,e95d93af-251d-470a-a062-fa1922dfa9a8

Requesting any Bluetooth Device...
> Name:             BBC micro:bit [vagap]
> Allowed Services: 00001801-0000-1000-8000-00805f9b34fb
                    0000180a-0000-1000-8000-00805f9b34fb
                    e95d93af-251d-470a-a062-fa1922dfa9a8
                    e95d93b0-251d-470a-a062-fa1922dfa9a8
                    e95dd91d-251d-470a-a062-fa1922dfa9a8
Connecting to GATT Server...
Getting Services...
Getting Characteristics...
> Service: e95dd91d-251d-470a-a062-fa1922dfa9a8
>> Characteristic: e95d7b77-251d-470a-a062-fa1922dfa9a8 [READ, WRITE]
> Service: e95d93af-251d-470a-a062-fa1922dfa9a8
>> Characteristic: e95d9775-251d-470a-a062-fa1922dfa9a8 [READ, NOTIFY]
>> Characteristic: e95d5404-251d-470a-a062-fa1922dfa9a8 [WRITE]
>> Characteristic: e95d23c4-251d-470a-a062-fa1922dfa9a8 [WRITE]
>> Characteristic: e95db84c-251d-470a-a062-fa1922dfa9a8 [READ, NOTIFY]
> Service: 0000180a-0000-1000-8000-00805f9b34fb
>> Characteristic: 00002a24-0000-1000-8000-00805f9b34fb [READ]
>> Characteristic: 00002a26-0000-1000-8000-00805f9b34fb [READ]
> Service: e95d93b0-251d-470a-a062-fa1922dfa9a8
>> Characteristic: e95d93b1-251d-470a-a062-fa1922dfa9a8 [READ, WRITE]
> Service: 00001801-0000-1000-8000-00805f9b34fb
>> Characteristic: 00002a05-0000-1000-8000-00805f9b34fb [INDICATE]

@danjenkins Is that something you've seen before?

[beaufortfrancois]

Wooo... I'm not sure why but disabling DFU service, Event service & standard BLE device information service makes the trick. I can now see all LED service characteristics:

Requesting any Bluetooth Device...
> Name:             BBC micro:bit [vagap]
> Allowed Services: 00001801-0000-1000-8000-00805f9b34fb
                    e95dd91d-251d-470a-a062-fa1922dfa9a8
Connecting to GATT Server...
Getting Services...
Getting Characteristics...
> Service: e95dd91d-251d-470a-a062-fa1922dfa9a8
>> Characteristic: e95d7b77-251d-470a-a062-fa1922dfa9a8 [READ, WRITE]
>> Characteristic: e95d93ee-251d-470a-a062-fa1922dfa9a8 [WRITE]
>> Characteristic: e95d0d2d-251d-470a-a062-fa1922dfa9a8 [READ, WRITE]
> Service: 00001801-0000-1000-8000-00805f9b34fb
>> Characteristic: 00002a05-0000-1000-8000-00805f9b34fb [INDICATE]

[beaufortfrancois]

Here's what I would recommend for this patch then:

• Document memory issue in README
• Emphasize your your micro:bit led service in README. Could it be part of this demo folder?
• Error should be more helpful than just Could not connect to bluetooth device!. Add Web Bluetooth error message in dialog.

[beaufortfrancois]

For info, here's my micro:bit program I've used to make it work: https://developer.mbed.org/users/fbeaufort/code/microbit-ble-open/

And specifically the diff for inc/core/MicroBitConfig.h

diff -r 2fc7d7c2fffc -r 04376b21995b inc/core/MicroBitConfig.h
--- a/inc/core/MicroBitConfig.h Wed Jul 13 12:18:46 2016 +0100
+++ b/inc/core/MicroBitConfig.h Thu Jul 21 07:19:19 2016 +0000
@@ -101,7 +101,7 @@
 // For standard S110 builds, this should be word aligned and in the range 0x300 - 0x700.
 // Any unused memory will be automatically reclaimed as HEAP memory if both MICROBIT_HEAP_REUSE_SD and MICROBIT_HEAP_ALLOCATOR are enabled.
 #ifndef MICROBIT_SD_GATT_TABLE_SIZE
-#define MICROBIT_SD_GATT_TABLE_SIZE             0x300
+#define MICROBIT_SD_GATT_TABLE_SIZE             0x700
 #endif

 //
@@ -173,7 +173,7 @@
 // Enable/Disable BLE pairing mode mode at power up.
 // Set '1' to enable.
 #ifndef MICROBIT_BLE_PAIRING_MODE
-#define MICROBIT_BLE_PAIRING_MODE               1
+#define MICROBIT_BLE_PAIRING_MODE               0
 #endif

 // Enable/Disable the use of private resolvable addresses.
@@ -187,7 +187,7 @@
 // Open BLE links are not secure, but commonly used during the development of BLE services
 // Set '1' to disable all secuity
 #ifndef MICROBIT_BLE_OPEN
-#define MICROBIT_BLE_OPEN                       0
+#define MICROBIT_BLE_OPEN                       1
 #endif

 // Configure for open BLE operation if so configured
@@ -234,21 +234,21 @@
 // This allows over the air programming during normal operation.
 // Set '1' to enable.
 #ifndef MICROBIT_BLE_DFU_SERVICE
-#define MICROBIT_BLE_DFU_SERVICE                1
+#define MICROBIT_BLE_DFU_SERVICE                0
 #endif

 // Enable/Disable BLE Service: MicroBitEventService
 // This allows routing of events from the micro:bit message bus over BLE.
 // Set '1' to enable.
 #ifndef MICROBIT_BLE_EVENT_SERVICE
-#define MICROBIT_BLE_EVENT_SERVICE              1
+#define MICROBIT_BLE_EVENT_SERVICE              0
 #endif

 // Enable/Disable BLE Service: MicroBitDeviceInformationService
 // This enables the standard BLE device information service.
 // Set '1' to enable.
 #ifndef MICROBIT_BLE_DEVICE_INFORMATION_SERVICE
-#define MICROBIT_BLE_DEVICE_INFORMATION_SERVICE 1
+#define MICROBIT_BLE_DEVICE_INFORMATION_SERVICE 0
 #endif

 //