Elmod Bluetooth DIY module

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Rad_Schuhart
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Re: Elmod Bluetooth DIY module

Post by Rad_Schuhart »

Hi Rochesb, there is a typo mistake in your post. You wrote two times HC 05.
But yeah, HC 05 can be master and slave, and HC 06 only slave.

I have seen videos of people connecting the modules to arduino boards. I have no clue what are they doing and I barely dont understand anything, but as you point, I think thats what we need... A guy with propper knowledge conecting the Elmod module to arduino, and to copy the code.

According to the bluetooth manual, the device should be recognized as "ElmodBT" (or something similar, I am talking from memory) and now with my module plugged to the board, I find it with the name "HC 05". So maybe this is something to consider.

Again, I need the help of more skilled people here.
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Re: Elmod Bluetooth DIY module

Post by rochesb »

Thanks for pointing out my typo.....corrected now. I must point out I have only dabbled with Bluetooth so I cannot provide a solution....

A quick Google suggests it is possible to 'extract' the firmware from one bluetooth module & write it to another, so it should be possible (but maybe illegal?) to 'clone' the Elmod Bluetooth module firmware & settings. Obtaining the hardware to do this would probably outweigh the cost of buying an original Elmod Bluetooth module so it is probably not worth the effort.

However, you might find this link helpful in interrogating (& possibly changing?) these modules. I haven't tried it myself but it might let you change the identity of the module from 'HC 05' to 'ElmodBT' ?

https://www.hobbyist.co.nz/?q=bluetooth ... igurations

It looks like it uses a program designed for Arduino communications to talk to the Bluetooth module via a USB/RS232 Serial adapter
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Re: Elmod Bluetooth DIY module

Post by Rad_Schuhart »

rochesb, thats extreme invaluable info, thanks for the link.

As wibbly said, I dont think Elmod reinvented the wheel, so maybe if we change the bluetooth board´s name, and try all the different baudrates, we might be able to set up a connection.

After reading the tutorial, I think that we might not need expensive equipment to investigate what is inside the elmod bluetooth module. Maybe just with that FTDI board we could check what´s inside...

But for that purpose we need somebody with the module...
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Re: Elmod Bluetooth DIY module

Post by Rad_Schuhart »

Well, I am back. I got another bluetooth module from aliexpress today, so is time to resume the fighting with it.

The link Herr Rochest gave us proved very interesting, and opened new windows to me. I´ve found this video tutorial which is almost the same but with a video:
http://arduino-er.blogspot.com/2016/04/ ... hc-05.html

And I managed to connect the module to the computer with just a FTDI adaptor. No extra arduino boards needed.
Once connected I changed the module's name to ElModBT like the original module, and the password to 0000.

I will try to plug it in the elmod board tonight, and we will see if it works. Fingers crossed...


If somebody with more ideas is reading this thread, please, throw some light to us!
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Re: Elmod Bluetooth DIY module

Post by wibblywobbly »

After having my Bluetooth module sat in my parts bin for months I pulled it out today and took a look.

The apk was downloaded and installed.
The Bluetooth module was hooked up to a 5 pin plug.

I used:

RXD
GND
VCC
EN

I ran the app.
Powered on the tank and the Bluetooth light was flashing.
I pressed the pairing icon on the phone and held down the button on the Bluetooth.
I typed in the password 1234 and the pairing was successful and appeared as HC05 on the phone.

All I can get on the phone is the Elmod logo screen. Swiping the screen should display the Fusion configuration menu's but it has no effect.

Something is stopping the app from working but I don't have a clue what it is? Maybe the app needs to see the device name as Elmod, but with no means of changing that...?

The Elmod app is displayed as available to copy, so I am assuming that it can be edited. I am also wondering whether the app can be edited to accept HC05, rather than the Elmod name?

Any suggestions anyone? I have Arduino boards here, but this is all new territory for me. 8O
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Rad_Schuhart
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Re: Elmod Bluetooth DIY module

Post by Rad_Schuhart »

Hi, long time I dont mess with it, but I managed to change the name of the HC05 bluetooth module, among other things, and it did not work.
After a lot of trial and error I ended buying an original module, and works well. I think I will open it at some point to try to see what is it about.
I might do it tonight. Also the name was longer than "elmod" but I have to check it later.

I must say it is a great add for the board, being able to modify everything on the fly, and also seeing the battery voltage, is a nice add for the hobby.
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Re: Elmod Bluetooth DIY module

Post by wibblywobbly »

There is a certificate file attached to the apk file. It shows the name Elmod1 in there. The problem with certificates is that if the apk is changed then the certificate has to be edited so that the name, checksum etc all match. This may be where the problem is?
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Re: Elmod Bluetooth DIY module

Post by Rad_Schuhart »

Ok, I removed the heat shrink tube from the bluetooth module, and unlike the USB connector it is indeed a self made bluetooth module. It has written "elmod" and so on in the pcb.

Anyway not everything is lost, I am sure we can end making our own modules.
I will upload some pics tomorrow.
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Re: Elmod Bluetooth DIY module

Post by wibblywobbly »

The guys at Elmod are very clever, though they may have had them specially made in Germany rather than in China. Better quality control that way. There is an app editor on Google Play, but it's not free. I would buy it but if there is something else stopping a DIY version from working it would not be a wise investment. :/

I found this Bluetooth manual.

https://developer.android.com/guide/top ... /bluetooth

Pairing and Connection are two different functions.
Two devices can be paired but they won't connect unless the server/client keys match.
So the device name has to match, and so does the UUID.
The certificates and digital signature will also need to match.
As to whether this info is held anywhere else within the app files, it's difficult to tell as they are binary, without a hex reader/writer.
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Re: Elmod Bluetooth DIY module

Post by Rad_Schuhart »

This is the module + the pcb with the antenna

https://www.electrodragon.com/product/3 ... rs232-ttl/
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