Thanks for the initiative!

[blynkkk]

Just came across your work in progress. Let us know if we can help with something.

Looking forward to starting using this plugin and spreading the word about it

[ilcato]

I'm trying to build a first usable version. Just added read support for switch. I plan to have such a version in a few days. It could be useful to have an api on the server to look for changes in order to automatically update the homekit status. Currently the only option I have is to perform a periodic polling on all pins -> to heavy.

[doom369]

Do you mean webhook on pin change?

[ilcato]

Yes

[ilcato]

@blynkkk : how do I refer to a physical pin through the Rest API. I'm able to read and write to a virtual pin. But what is the syntax for physical one (digital and analog)? Is it D1, D2, ... and A1, A2, ... or GP1, GP2 as in the Blynk app?

[doom369]

Is it D1, D2, ... and A1, A2

yes.

[ilcato]

@doom369 : is it correct the following behavior?

• I have a button on pin D4
• I associated it to a Value Display widget on the Blynk app with a 1 sec parameter
• the Blynk app correctly visualize the value of the pin
• if I read the same pin through the rest API I'm able to see the correct value but only if the Blynk app is running in foreground (iOs app) If the app is not running or is in background the API doesn't reflect the current status of the button.

If this is correct I don't think we can use Homekit.

[doom369]

Do you mean physical button? If so you need to wrap digital pin with virtual pin. And when you press physical button you need to send Blynk.virtualWrite(); Have a look in sketches we provide.

[ilcato]

This way, right?

BLYNK_READ(V2) { int val = digitalRead(D2); Blynk.virtualWrite(V2, val); }

[doom369]

yes. you can also use button interrupt, so no need to have a timer on app.

[ilcato]

BLYNK_READ(V2) is called when the Blynk app is running and there's a Value Display widget associate to V2. If I only have the REST client calling the Blynk Server for reading V2 it receives the last value polled by the app. What I need in order to have, for example, an HomeKit accessory of type ContactSensor associated to a virtual (or physical) pin is a REST call that function without the Blynk app running.

[doom369]

https://github.com/blynkkk/blynk-library/blob/master/examples/More/ButtonInterrupt/ButtonInterrupt.ino https://github.com/blynkkk/blynk-library/blob/master/examples/More/ButtonPoll/ButtonPoll.ino

[ilcato]

Yes, this is what I'm trying to avoid. What I'd like to have is a mechanism similar to the one adopted for the Blynk App widget: the app calls "something on the server" and is able to retrieve the value of the pins (virtual, digital, ...).

[doom369]

This is not implemented for REST API. But you could use for this case websockets.

[ilcato]

Is there a socket entry point in Blynk server ?

[doom369]

Here is example https://github.com/blynkkk/blynk-server/tree/master/docs/websocket and here https://github.com/tzapu/node-red-contrib-blynk-websockets

[ilcato]

I completely missed the server repository. I just downloaded the server binaries.

I will look this further info.

Thank you

[doom369]

Have fun =)

[ilcato]

@doom369, in my understanding with the script that you indicated I'm able to perform an hardware role with respect to the Blynk server. Is it right? What I'm looking for is to have the ability to execute like the Blink App in order to control the Blynk devices.

[doom369]

Is it right?

Yes.

What I'm looking for is to have the ability to execute like the Blink App in order to control the Blynk devices.

Could you please describe exactly and detailed use case you want to achieve? I'm afraid I don't understand your goals.

[ilcato]

Ok, I want to be able to control Blynk hardware through HomeKit and Siri. So, for example, in order to have the ability to ask Siri something like "what's the temperature in the living room?" (provided there's a temperature sensor connected to a pin on an Arduino) I need an API on the Blynk server that allows to query the value of the pin. This is what the REST API is supposed to do I think, but in my experiment this is true only if there's the Blynk App running that polls (with the set frequency) the given pin.

[doom369]

Ok. Got it. So yes. This is true for polling and this is how polling suppose to work. Polling is application based, not server side. However it is possible to achieve what you want. All you need to do is

Blynk.virtualWrite(V5, value);

whenever you think it is required in your code. Here is a basic example of how to write value every second.

And you can call at any time HTTP GET request in order to get latest value for V5.

[ilcato]

Understood. And what about the "-mode app" in the Java Blync client ? What is it suppose to do? Isn't it possible to go that way in order to be able to query the server the same way the Blynk app do?

[doom369]

Yes, you can do that with Blynk client, but it was designed only for integration tests in order to simulate Blynk apps. So it has no documentation, guides, etc.

[ilcato]

Ok. I will check this path. It has minor impact on the way in which you build Things.

[doom369]

Have in mind. Client will work only for local server as we use mutual SSL on Blynk Cloud.

[ilcato]

Ok. A side question, why didn't you adopt existing IoT protocol like MQTT ?

[doom369]

Few reasons :

• For application side it is absolutely unnecessary. Own protocol or websockets are much better and simpler.
• For hardware side it is a bit over engineered. It was designed for low bandwidth and for many different use cases. Blynk protocol also lightweight but much more simpler, as we don't need to cover all use cases.

We will add MQTT support for hardware side soon. But at the moment we have only few users who care about that.

[ilcato]

@doom369: it seems that the following https://github.com/blynkkk/blynk-library/blob/master/scripts/blynk_ctrl.py may be the right answer to my need.

[doom369]

Nice. Looking forward to see working prototype.

[ilcato]

@doom369: I dismiss the "bridge" approach of the blynk_ctrl.py because it present the same problem of the other approaches I test. I switched back to the idea of implementing a client app approach on the TCP SSL entry point (the same of the Blynk app). I was able to write a node.js module that implement the capability. Now I have all the building blocks for completing the homebridge plugin for the HomeKit/Siri access to Blynk.

In the mean time I just published the node.js module on npm: blynk-app-client. It is a very first draft that I will update with the lesson learned in writing the homebridge plugin.

[doom369]

@ilcato cool. You are awesome. Thanks for sharing!

[ilcato]

@doom369: blynk-app-client module is now pretty complete for my scope.

[ilcato]

@blynkkk, @doom369 : for the homekit/Siri integration I have reached a road block. Situation:

• homekit/Siri needs: an API that allows read/write access to the device pins without the Blynk mobile app running
• Option 1: the Blynk rest API (the first I tried). This approach fails because it requires the Blynk mobile app running
• Option 2: the TCP Hardware Socket API with a virtual Bridge component (like the blynk_ctrl.py available in blynk-library project). This approach fails too because it requires the Blynk mobile app running. The WebSocket API is similar
• Option 3: the TCP App Socket API (the same used by the Blynk mobile app). I wrote a node module in order to be able to access the server this way, see blynk-app-client With this approach there's no need to have the Blynk mobile app running. But there's a problem with the read operation on pins that are bounded to a control widget

For example: if I have digital pin 5 connected to a Button and I try to read its value through the hardware command, like

blynk.hardware(101, "d", "r", 5);

it fails because it is looking for a FrequencyWidget connected to the same pin, that is impossible because it is already connected to the Button Widget that is not a FrequencyWidget.

In HardwareAppLogic.java row 69 there's:

        case 'r' :
            FrequencyWidget frequencyWidget = dash.findReadingWidget(split[1].split(StringUtils.BODY_SEPARATOR_STRING), message.id);
            if (frequencyWidget.isTicked(split[1])) {
                session.sendMessageToHardware(ctx, dashId, new HardwareMessage(message.id, split[1]));
            }
            break;

If I modify the logic in:

        case 'r' :
            FrequencyWidget frequencyWidget = dash.findReadingWidget(split[1].split(StringUtils.BODY_SEPARATOR_STRING), message.id);
            if (frequencyWidget) frequencyWidget.isTicked(split[1]);
            session.sendMessageToHardware(ctx, dashId, new HardwareMessage(message.id, split[1]));
            break;

and in DashBoard.java row 104 I modify it in the following way:

from

    throw new IllegalCommandBodyException("No frequency widget for read command.", msgId);

to

    return null;

it works and it also update the LastRequestTS if necessary.

Are you able to check if this (or a similar change) is possible to introduce in the Blynk server?

Thanks.

[doom369]

Option 1: the Blynk rest API (the first I tried). This approach fails because it requires the Blynk mobile app running

It doesn't. Code.

Suggested change is not correct from point of view of server. Button is not supposed to send reading command. The only way at the moment would be to use HTTP API.

Do you use Blynk cloud? Could you please explain why you think HTTP API doesn't work without running app?

[ilcato]

@doom369, I'm using local Blynk server. I access digital pin number 4 with a GET request on:

https://10.0.0.102:9443/f8fc77e07d6b415984f683ccd9bd2e4a/pin/D4

It respond with the last value presented on widget display on the Dashboard on the mobile app when the dashboard was running.

If it is running the previous GET always respond correctly but as soon as I stop the Dashboard, put the app in the background or kill it the GET request respond with the last value read by the widget while the app was running.

I think that the reason is because in the REST API you simply return the value stored in the Widget in the Dashboard while in the App API you "sendMessageToHardware" in order to retrieve the value directly from the board. If the App is running it periodically read the value from the board and stores it in the widget.

[doom369]

You are right. I'll think what we can do here.

[ilcato]

@doom369: any news?

[doom369]

Not yet. Busy with next release.

[doom369]

https://github.com/blynkkk/blynk-server/issues/118 will try to resolve it today

[ilcato]

great!

[doom369]

@ilcato I spent few hours in order to find best solution, but I'm afraid implementation of such HTTP API may cause performance issues due to async nature of Blynk server. Your polling solution is only possible at the moment. I hope we will introduce WebHooks very soon so your solution may be simplified.

[ilcato]

@doom369: let me try to recap.

In order to finalize the homebridge-blynk plugin I need to have the possibility to read and write a pin. Consider this scenario:

• an Arduino board controls a lightbulb through a relay connected on digital pin 5
• in the homebridge plugin an HomeKit Switch is associated to the relay in order to allow a Siri command like "turn on the lamp" to be sent and transformed in to a digital write 1 to pin 5. This is currently possible.
• the plugin needs also to be able to manage Siri queries like "Is the lamp turned on ?". For this query I need to read the value of pin 5. This is not possible if I already associated the pin to a Blynk controller widget.

Please try to reconsider the change that I proposed two weeks ago that I propose as a pull request on the Blynk server. In this way all works as I expected.

[doom369]

the plugin needs also to be able to manage Siri queries like "Is the lamp turned on ?". For this query I need to read the value of pin 5. This is not possible if I already associated the pin to a Blynk controller widget.

This is possible if you will send Blynk.virtualWrite on pin change to server, so server will always have latest state.

[ilcato]

But this limits the scope to the virtual pins and needs to implement logic on the device side.

[doom369]

Indeed virtual pins where designed exactly for such cases.

and needs to implement logic on the device side.

yeah =).

I'll accept your proposal in PR and will release update soon.

[doom369]

@ilcato released 0.13.2

[ilcato]

@doom369, @blynkkk I'm glad to announce the first usable version of the homebridge-blynk plugin. Please have a try and ask Siri to "turn on the computer" !

[doom369]

Nice!

[blynkkk]

super cool! thanks! :pray: Will test it out on a weekend.

@ilcato Do you have a "getting started" somewhere?

[ilcato]

@blynkkk, basically:

• select a platform on which to install the plugin (I'm using a Raspberry, but any platform that support node.js may be adopted)
• install homebridge (follow instruction) on https://www.npmjs.com/package/homebridge
• install the blynk homebridge plugin: sudo npm install -g homebridge-blynk
• create a config.json file in the .homebridge directory of the user that run homebridge (see example in https://github.com/ilcato/homebridge-blynk/blob/master/config.json)
• run homebridge (and create an autostart file on the hosted platform)

For the config file:

• specify credentials and dashboard name of an existing dashboard on the referred local Blynk server
• assuming a switch within the dashboard specify in the accessories parameter of the config.json file:

{ "name": "SwitchD5", "widget": "Switch", "mode": "SWITCH", "caption": "Lamp 1", "pin": "D5" }

where:

• name will be the accessory name from the HomeKit point of view
• widget must be "Switch"
• mode can be "SWITCH" or "PUSH"
• caption will be the name you should refer to from Siri
• pin is the board pin connected to the switch

Use an HomeKit app to add the accessory to the iPhone/iPad, e.g.: MyHome

After that you can say to Siri:

turn on lamp 1