Simultaneous Stereo and Commander

The most versatile and user friendly E-Stim control unit available today. If you want More Power, More Control, and more fun, then the 2B is the one you want.
mills
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Re: Simultaneous Stereo and Commander

Post by mills » Tue Aug 22, 2017 11:47 am

Hello!

Wow... the possibility to connect via serial-BT would be great for my raspberry pi project. :-)
By the way... the HC-05 has another problem. I think, this module has 3.3V level, and as far as I know, the
serial interface of the 2b is 5V.

Ciao
Andi



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LondonSubNigel
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Re: Simultaneous Stereo and Commander

Post by LondonSubNigel » Tue Aug 22, 2017 1:22 pm

Yes, it is, but you can fudge this (with caveats about warranty etc).

The 2B is sending 5v serial signals, but in practise as far as receiving a signal goes, 3.3v is above the level at which is considers the signal to be high, so you can send from an HC05 into the 2B. For the data in the opposite direction, you need to drop the voltage from the 2B to around 3 and a bit volts.

Simplest solution is to put a 2k2 and a 3k3 resistor in series. The transmitted data FROM the 2B is connected to the 2k2 resistor; the connection between the two is connected to the Rx pin on the Bluetooth module, and the bottom of the ladder to ground. This will give a signal level of around 3.2v into the module, which is near enough to register correctly.

Of course, the proper way to do this is with a level shifting chip, but in practice I've found this suffices. Details of how to make a BT adaptor are on my web site. As ever, plug home made things into your 2B at your own risk, etc etc.

mills
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Re: Simultaneous Stereo and Commander

Post by mills » Fri Aug 25, 2017 10:54 am

Hi!

I found a solution for the level problem...
https://www.amazon.de/gp/product/B00V07 ... UTF8&psc=1

This BT-module is a little more expensive, but there is a level shifter already onboard, so it is capable
for using in 3,3 and in 5V environments.

Ciao
Andi

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Re: Simultaneous Stereo and Commander

Post by LondonSubNigel » Fri Aug 25, 2017 1:37 pm

That is an interesting module, but I can't see in the data sheet where it says it has a level convertor.

Also, note that it's a BLE (Bluetooth Low Energy module) with a transparent UART mode, which is actually quite a different beast to the HC modules. In particular, although once the module is connected to a remote device, it will pass data transparently as if it was a plain cable replacement, the device on the other end of the connection has to handle the BLE connection, which means searching for the device with a specific service, and writing data to the characteristics of that service.

In programming terms, it's not a massive deal - just a bit fiddlier - but in practical terms it means that while a device with Bluetooth 2 has a well defined "serial port" or "cable replacement" option - you can plug a BT adaptor into a 2B and connect to it easily from a Mac or Windows PC with Bluetooth - the same is not going to be true of this. The device you're connecting from will need BLE (Bluetooth 4), and a way to make the connection to this specific type of module.

I see on the wiki page there are some apps that you can use to demo the functionality, but in terms of making this module work with existing apps, then I think it's almost certainly the case that you'll have to re-compile the apps, specifically to look for a device of this type, and write to its own specific BLE characteristics.

I've been doing some tinkering with BLE modules lately, and because of the way the protocol's designed, there isn't a standard UART mode included in the spec. Lots of manufacturers offer one, as in the case of this chip, but they're all different, in terms of the UUID and the characteristic, and the fine details of how they indicate (or not) when a connection has been made. So, you can't write a generic app like (say) my estim4android that will work with all BLE modules in the same way that you can for traditional bluetooth, with its Serial Port Profile (SPP).

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Re: Simultaneous Stereo and Commander

Post by mills » Thu Aug 31, 2017 7:15 am

Oh, my god...

I overlooked the fact, that this is an BLE module... :-D
But, thanks to Amazon, it was no problem to send the module back for full refund.

Now I found another module with a HC-05 chipset, and they say, that it is 5v tolerant.
Yesterday I applied this module to the 2B, and it works like a charm. In the worst case, the HC-05
will blow up, but this would no drama... the module only costs a few euros. ;-)

Here's the link to this module, I'm recently testing:
https://www.amazon.de/gp/product/B00PL7 ... UTF8&psc=1

I posted some videos in another post here to demonstrate the functionality.

Cu all
Andi

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