How can i send a byte array with BluetoothLE extension?

[George Loungos]

Hello, i successfully connected to a BLE device and i found that i must send a byte array to control it. It turns on if i send "5510010D0A" and off if i send "5510000D0A". That's a 5 byte array. So my question is if it's possible to send it with the Bluetooth BLE extension and if it is then how?

I really appreciate any help you can provide.

[Abraham Getzler]

You can generate hex characters using a trick of one of the Web component blocks, then join them together into a text string.

See attached example.

ABG

[George Loungos]

Hello Abraham and thanks for your reply but i don't exactly understand how your answer helps me with my problem. With BluetoothLE extension i can send only 1 byte and i must send 5.

[Abraham Getzler]

Does the BLE extension allow you to send arbitrary text strings?

That's what I was shooting for with my text encoding techniques.

ABG

[George Loungos]

It has a WriteStringValue block so i thing it can send a string.

(Oct 2017 edit:  These blocks and the .aia are obsolete.

See the AI2 FAQ for the current BLE blocks - ABG)

[Abraham Getzler]

So the string value you would send would be a five-way text JOIN of

hexify("55"), hexify("10"), hexify("00"), hexify("0D"), hexify("0A")

Use the blue box to add sockets to the JOIN block as needed.

The hexify Web trick only works 1 byte at a time, unfortunately.

ABG

[George Loungos]

It works like a charm. Thank you for your help i really appreciate it...!!!

[Abraham Getzler]

Feel free to post the completed project here, so I can point to it from my FAQ's BLE section.

https://groups.google.com/forum/?utm_medium=email&utm_source=footer#!msg/mitappinventortest/2cd6Uz__xA0/cPQSiZpcDAAJ

We could use good samples of long hex strings for device control.

ABG

[Ghica]

@ABG: pointing to this thread in the BLE section of the FAQ would already be very helpful!
Cheers, Ghica.

[Abraham Getzler]

Link to the hexify post in this thread added to the FAQ's BlueTooth/BLE section.

https://groups.google.com/forum/?utm_medium=email&utm_source=footer#!msg/mitappinventortest/2cd6Uz__xA0/cPQSiZpcDAAJ

Feel free to add a complete project to this thread.

ABG

[George Loungos]

My project so far is this one attached to the post. The device that i control is a Beewi smart led color bulb. It has many other futures like change the RGB color, warm and cold light but all these are a diffirent 5 byte value that works the same way as on and off. 

[Abraham Getzler]

Nice and simple!

Do you have a link to the API you can add?

ABG

[George Loungos]

Which API do you mean?

[Abraham Getzler]

The place where you got the list of hex codes to send to turn the bulb on and off?

ABG

[George Loungos]

I didn't found exactly a site that provides me the hex codes. I used Bluetooth HCI and Wireshark to look at the log file. This is how i found the UUID and the hex codes.

https://medium.com/@urish/reverse-engineering-a-bluetooth-lightbulb-56580fcb7546#.6wdbt6xa6

[Abraham Getzler]

That should serve nicely.

Thanks for the links and the sample!

ABG

[Andrew Mckinney]

We are investigating this and adding this to our next version coming soon.

Andrew McKinney

MIT App Inventor 

Technical Lead.