Bluetooth module?


#1

And the Bluetooth module? For which application you plan to use with this module


#2

The bluetooth module is to allow people to send messages back-and-forth with the Tympan without needing to keep the Tympan connected via USB.

The bluetooth module is Bluetooth Classic, not Bluetooth Low Energy (BLE). So, it’s easy to use with both a PC or a phone. Future versions of Tympan will probably switch to BLE, which will make it easier to use with a phone, but harder to use with a PC.

There is currently one example sketch in the Tympan library that uses the bluetooth module. It is under the “Full Systems” menu. The example sketch is named “WDRC_8BandComp_wExp_wBT” (github here). Note the “wBT” at the end of its name, which stands for “with Bluetooth”.

In this sketch, the Bluetooth link is simply a copy of the USB link. With either Bluetooth or USB, you can adjust the audio processing settings of the Tympan via a text-based menu system. I think that it’s fun…but I’m biased…because I wrote it. :slight_smile:

When writing software for the Teensy to use the Bluetooth module, the link to the Bluetooth module is simply a serial connection, just like serial communication over USB. So, you can send or receive anything over that bluetooth link that you’d like. I recommend only sending text, because then you can use a Terminal program on your PC (or phone) to easily read and write messages to the Tympan.

One interesting use for the Bluetooth link would be to program the Tympan to be a sound level meter. It could continuously measure the ambient sound level and transmit the values over Bluetooth to your phone or PC. You could use it to monitor the loudness of your daily life. Yes, you can already do that with the microphone in your phone. But with Tympan, you have total control over how the data is processed and presented. Personally, I like having that much control.

Chip


#3

Interesting! Good idea with this sound level meter! One could create an application to materialize a bargraph on the screen of a telephone. :slight_smile:
I understand better with your explanation. Thank you!

By the way I already tried the communications between the Tympan and my phone well recognizes the bluetooth of the Tympan.
I wanted to use this bluetooth so that the eardrum can receive audio data and then the sound will be amplified after its conversion DAC.
Of course this will not be possible for this type of Bluetooth module


#4

I’m so pleased that you’ve used the Bluetooth connection! Yay!

You are exactly correct in how in can and cannot be used. It can connect to a phone or computer for sending messages. The data rate is limited to (I think) 115200 bps, so you can stream some data, but not audio.

To handle audio data, there is a specific protocol for Bluetooth audio, but the RN-41 module that we use does not support this protocol. The audio-enabled Bluetooth modules back when the board was first designed (e.g. RN-52) were even more expensive than this one.

Moving forward with future versions of Tympan, we are likely to revise the Bluetooth module. I want one that’s smaller and cheaper, but maybe we can also find one that does audio! Do you know of a module that does BLE and that does audio and that is smaller and cheaper than the RN-41?

Chip


#5

The Bluetooth Help Docs are now available in the Tympan docs wiki: Setting up a Bluetooth Terminal

This section will continue to grow, as product develops and/or more questioned are asked.

Thanks for your contribution to the Tympan!

Alison