bluetooth problem

[nicola...@googlemail.com]

Hi ia am currently programming with the MIT App Inventor 2 an app which is supposed to send the Lego EV3 a Message. currently i can connect to the EV3 but somehow my masseage dosen't work. if found thees informations :

"number" message is a float (4 bytes), LITTLE ENDIAN - this is important
"text" message is a US_ASCII encoded null-terminated string.
all lengths in formatted messages are little endian two-byte words (shorts) except for the "Mailbox name" field, which is a single byte
lengths for mailbox name and text message must include terminating zero.

and

https://wiki.qut.edu.au/display/cyphy/Mailbox+and+Messages

on the picture you can see what I sennd to the EV3. It would be creat if anyone could tell me what i am dooing wrong and how i can fix this.
greatings Nicola

ps. i hope you can understand my english it's not my native.

[Liz Looney]

Hi Nicola,

I don't have an EV3 yet, but thanks for posting the link to the EV3 bluetooth messaging protocol!

I'll respond sometime today with an answer.

-Liz Looney

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[Liz Looney]

Hi Nicola,

I found the problem. In your Button1.Click blocks, after sending the list (which includes the mailbox name), you send 4 (which should be the length of the message), then you send 97 (which is "a"), then you send the zero terminator character. The length of your message ("a") is actually 2. You need to change the message length from 4 to 2.

Please see the attached screen shot of blocks. I've put in lots of comments. I hope it helps.

Here are some other tips:

To send a 2 byte number, you don't need to create your own procedure (sentAB); just use the BluetoothClient1.Send2ByteNumber block.

You don't need to change HighByteFirst in your blocks. Just make sure the HighByteFirst checkbox is not checked in the Designer. (Also, the HighByteFirst setting does not have any affect when you use Send1ByteNumber. It only affects when you use the blocks that sends or receives 2 or 4 byte numbers.)

-Liz Looney

PS - I don't have an EV3 yet (it should arrive on Monday), so I haven't tried running this project yet.

[michael...@googlemail.com]

Hi Nicola, Hi Liz
I also tried to control my EV3-robots (simple move-forward-command) with an AI2-App.
I can connect via Bloototh, but my robot doesn't show any reaction too.

Before I search for faults in my (really very simple) APP:
Does anybody in the Forum know, if the NXT-Commands of AI2 generally works with the new EV3-Bricks at all ??

Greetings,
Michael

[Liz Looney]

Hi Michael,

From what I've read, the NXT components in AI2 will NOT work with the new EV3 bricks because the EV3 bluetooth commands are different than the NXT bluetooth commands.

-Liz

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[ralph.p....@gmail.com]

Has anyone talked to Lego about this?  My MAI2 programs work great with the NXT, but I'm also finding issues communicating with the EV3.  Lego's Commander Application is written for both IPad and Android and works with the Bluetooth of the EV3, so Lego seems to have no issues communicating with the Bluetooth of EV3. Perhaps Lego tech support can help with getting the Bluetooth driver to work. 

My MAi2 application hangs when trying to connect to the EV3.  I tried with the EV3 Ipad-Iphone setting both on, and off (not knowing exactly what it does), but it hung both ways. I know the EV3 has an additional output port compared to the NXT, so at least that would need to be taken into account/modified in the MAI2 NXT drivers for it to work. This issue will increase over time as more EV3 installs get out there. Hopefully someone will put it on the "nice to have" list of future development opptys for MAI2.

thanks for any updates Liz!

Ralph

[Neider Xavier Vergara Humanez]

Hi everybody, i´m also trying to communicate my EV3 whit an AI2 app by Bluetooth, i've been watchinig this code and i have some questions about, i understand that i need to program my EV3 to make the communication, is that right? if positive, how do i know what mailbox am i using? when i program my EV3 i LabView i just see MAILBOX1,2,3,4... Can somebody help me? i'm trying send a number or text to my robot and move motors depending on that received number, excuse my english, i'm not native.

Thanks.