Replicate Bluefruit Connect Text Input

MIT App Inventor Help
#1

Hi, thank you for checking this out. someone put together an Arduino Due with a “Adafruit Bluefruit LE UART Friend” for me to control the temperature of something.
I can use the Bluefruit Connect app to send UART commands to accomplish what I want to do, but was trying to make an app with buttons that would send the text instead.
To start, I have been able to create an app that scans for bluetooth devices, connects to the Bluefruit LE, and shows the buttons to enable/disable the heat… I installed the app successfully on my phone, and connected to the device, but when I try to enable it, the app just crashes. I assume that is because I am sending the command the wrong way. I have found some sources that talk about sending numerical values and strings, but none of them seem to exactly apply to what I am doing.
To start, I just want to have a button send the text “enable” like Bluefruit connect would, but at the push of a button instead of manually typing it out.
The complete set of commands is “enable” “disable” and “[desired temperature]”

References here:
This seems really useful, but I don’t know if it directly translates to what I want to do.
This seems to be the closest to what I am working on, but did not get me there.
I also found a blog post that said all example projects now have BLE build into them, but I’m not sure where to find the official example files. I cannot link to that article because I am a new user and am limited to two links per post. I did find a set of them from an old page on the site, and they did not have new BLE extensions in them.

My block layout:

2020-05-25 02_26_37-MIT App Inventor
2020-05-25 02_26_37-MIT App Inventor1305×933 277 KB

Bluefruit Connect Screenshot after connecting. It seems to report some active values:

Screenshot_20200525-022510_Bluefruit Connect
Screenshot_20200525-022510_Bluefruit Connect632×1335 76.6 KB

#2

Hi Brandizzle

Replace the BLE Block WriteBytes with WriteStrings.

BLE Write String

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#3

Thank you for the reply. That was the first thing I tried. It does the same thing. The app just closes.

#4

Stick with the Strings Block.

Other things:

  1. Is “Location” switched on?
  2. Is Developer/Debug mode switched on?
  3. Is there an Anti-virus App in addition to the one that came with the phone?
  4. Do you know for sure that the Uuids are correct?
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#5

Thanks for taking another look. Location has been on, as well as developer/debug. Unless one is baked-in, I don’t think I am running anti-virus. I very well might be missing something about the UUID. Following an example from a different project, I found something from the manufacturer and just put it in both fields. I did however find other examples in the forums where the characteristicUuid was different than the serviceUuid, but did not find any explanations as to why.

2020-05-25 16_02_38-UART Service _ Introducing the Adafruit Bluefruit LE UART Friend _ Adafruit Lear
2020-05-25 16_02_38-UART Service _ Introducing the Adafruit Bluefruit LE UART Friend _ Adafruit Lear1028×565 248 KB

#6

I found the DeviceCharacteristics and temporarily added to my app and ran it. Perhaps, I could use something from here:

Screenshot_20200525-233944
Screenshot_20200525-233944609×1286 172 KB

#7

And “Device Services”:

Screenshot_20200526-010510
Screenshot_20200526-010510632×1335 53.3 KB

#8

Try the BLE App from Google Play to get the “master” Uuids. They will be almost the same but not identical strings in most cases (this is not a rule but has become the norm).

The difference between the purpose of the Service Uuid and the Characteristic Uuid: The Service Uuid determines the type and number of Characteristics available - The Characteristic Uuid defines the types/values that are available. It’s easier to understand when you see the official list of both Uuid categories:


Many development devices simply use generic Uuids that do not hold any specific values.

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#9

It does look like you are actually already using Bluefruit’s generic Uuids. My only doubt is that your board might be a variant and have different Uuids. I have seen issues with these boards before - essentially, they are an Arduino template with built-in bluetooth and clearly the intention is to make things easier, but there seem to be quirks that actually make things more difficult. :upside_down_face:

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#10

… by the way, baked-in anti-virus is fine, the troubles with AV manifest when people add a third party AV App.

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#11

What is happening on the board side - perhaps there is an issue in your script/sketch?

Edit: I think it should be this one - I’d like to see it:

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#12

It’s probably a good idea to ask about Bluefruit BLE + App Inventor in the Adafruit forum - it’s possible an Adafruit enthusiast can help.
https://forums.adafruit.com/

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#13

Thanks for your continued help. Using the BLE app gave a bunch of numbers (one set for each of Device Name, Appearance, Peripheral Preferred Connection Parameters, Service Changed, and three other random unlabeled things). None of them matched what I was using before. I plugged in one and the app didn’t crash when running it. Nothing happened, but that’s still an improvement! I will ask for the sketch from the person who put this together for the sketch, and will also post in the other forums and report back later. You’re awesome. Thanks!

#14

Fingers crossed!

#15

It does not seem super active on the adafruit forums. On the off chance that someone who is in real deep, this is the source for App that I am trying to replace:


I’m going to dig through and look for clues… but I literally have no idea what I am doing. :}

#16

There is something of interest in the Manifest, requiring ACCESS_FINE_LOCATION. We have usually used ACCESS_COURSE_LOCATION, I don’t know if the latest BLE extension has changed this - it is also dependant on the version of Android, favouring the latest versions.

So, assuming the extension is already requesting Fine Location, the blocks below will be nothing but a red herring:

Start by trying the ACCESS_FINE_LOCATION permission only.

Permissions

You should have in your possession the Script/Sketch used to drive the microprocessor - the whole point being that you can reset the board with the manufacturer’s script and also use that script as an example/template for your own code.

#17

Thank you for the additional information. I think it was already getting those permissions, because these blocks seem to execute correctly:
blocks
I assume that if it did not connect, this would not execute. But I may be misunderstanding the suggestion, so I gave it a try and was given an error.
In any case, I think it is time for me to give up. This is probably too far over my head. Thank you so much for all you have done @ChrisWard
I checked out your site, and did not find anything that I could do. If you would like me to buy you a cold one, you can DM me your paypal. :]

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#18

I have not used this device.

In your code I notice that ServiceUUID is 6E400001-XXXXX
and CharacteristicUUID is also 6E400001-XXXXX

Change CharacteristicUUID to
6E400002-XXXXX

or

6E400003-XXXXX

1 Like
#19

Thanks for the suggestion, but this did not make a difference.

#20

Our colleague Gerrikoio has got a BlueFruit Board working with App Inventor: