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So I'm hopelessly lost right now. I found an attractive bluetooth chip from Nordic Semiconductor (the NRF52840) that I want to use for a couple project ideas I have. Now I have an HC-05 module for my arduino, so I'm not entirely lost on programming a bluetooth module perse, but I really need advice on how I can make my own. I want to make a bluetooth module that works exactly like the HC-05 but on a much smaller scale. I'm talking fitbit small. I'm not making a smartwatch or fitbit, but that's relatively the size I would need it to be.
So bottom line to whoever got lost in that mumbling explanation of my hopelessness, I need some advice on how to develop my own Bluetooth module PCB. The onboard chip will be the aforementioned NRF52480. Thank you to anybody who helps!!
Given that you are endeavoring in a very complex task, I would recommend you to start from the reference designs provided by the chip manufacturer. They are very valuable, especially when dealing with RF.
See here and here, for example. About RF design, this talk may be interesting for you as well.
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For example, how would a washing machine play a specific sound (MP3 or WAV or whatever) when finished? Which external components are needed?
I know this is a really vague question but I could not find any real solutions except some kind of MP3 player module which seems to be more "end-user friendly" instead of being used programmatically (skip and pause buttons).
Various beeps can be made simply by toggling a pin, but I assume your are looking for something more melodious, and without using a sound synthesiser.
For short sound bites: you can store them in (external) memory and play them through a DAC, if your MCU has one. I put a basic implementation of this for SAMD21G-based Arduinos here; the idea is the same for all MCUs that have a DAC. If your MCU doesn't have a DAC, you can use an external one, or make a "poor man's DAC" by using PWM and low-pass filtering the output.
Another option is creating an I2S stream from stored samples and send them to an external amplifier (module) that accepts I2S. It helps when your MCU has an I2S peripheral.
For longer sounds, your best bet is probably playing them from a MCU-controlled MP3-player, because you need the SD-card storage or a similarly large storage anyway for large sound files.
In all cases, you'll need an external amplifier and speaker.
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I'd like to write some library/app to interact with Galaxy Buds.
I assume that this would require me to somehow sniff packages it sends to my mobile telephone and get which corresponds to what command(volume/pause/play) and so on. And then write some wrapper for it? I'd like to make this app/library reusable between different Linux distros, and not-that-hard-portable to Mac OS.
Knowing all that I still in the place where I'm not sure where to start from.
I'd appreciate suggestions to any part of this process e.g (Programming language selection, software for BT sniffing ...)
I do have some experience with C#/Java/C++, but I'm willing to learn if these aren't most suitable for solving the issue.
I don't know that much about the libraries needed for such a solution, but as far as sniffing is concerned, I know that Wireshark (WireShark_Bluetooth_Sniffing) is a good starting place.Once you isolate the touch commands, I assume you can map them to media commands, as described here: D-Bus_Media_Commands
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I'm not quite sure where to post this question, but I think Stack Overflow has a lot of smart people who could help.
I'm wondering if there is a way I can combine programming and electrical circuits. Can I somehow turn my computer into a signal generator to create AC waveforms which I could apply to an external circuit that I've created? Could I then program my computer with say C++ code to change the amplitude/frequency of the waveform (hopefully this if possible doesn't require assembly language which I know nothing about expect that its code that operates more directly with the CPU or something). Basically, I'm looking for a way to combine coding with electrical circuits. Anything will do. I just want to get better at both because they both interest me.
Yes, you can use your audio channel.
You have to consider its frequency response: (theoretical Maximum of 20kHz?)
You also have to buffer the audio output. Use an opamp as a buffer for that. You do not want to overload your audio jack.
You will run into challenges of how "Fast" you can send data to your audio channel. But I think it is possible.
Another way is to use a good old parallel port, IF you have one :). Those are nice to command some electronics.
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I want to know about Linux audio, i spent a lot of time on reading but i didn't understand(clearly). Can anybody give a brief information on various Linux audio sub systems(Like OSS, ALSA, JACK, Gstreamer, Phonon, Xine)?.
Any help, Thanks in advance.
I once wrote a famous blog post about the jungle of Linux audio output formats. You can find it here.
Regrettably, the picture is no longer there, here's a copy:
It's a bit old (dating from 2007), but I hope it gives you the general idea. OSS and ALSA are the layers closest to the actual audio hardware. All the other libraries and frameworks simply talk to those lower layers. And as you can see, some of these libs and frameworks actually have wrappers around other libs and frameworks.
Which layer you want to call upon depends largely on what you wish to accomplish.
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I'm having a hard time finding a software that would emulates a Bluetooth keyboard (and/or mouse) that follows HID standard.
I've already found one, but I couldn't get it working: http://mulliner.org/bluetooth/xkbdbthid.php
I'm only interested in a solution that uses HID standard so that other machines can immediately recognize the soft as Bluetooth hid device, without the need of any pre-installed softwares. (Running under Windows or Linux if possible.)
Would it be possible to write a code in java to emulate Bluetooth hid devices?
Any help would be very appreciated, thanks!
It's been a while since you asked the question, but I'm going to add this answer anyway, it may help you or someone else.
I'm also interested in Bluetooth HID emulation, ideally from within some Java/Android code. However, I came across this Python-based script/project:
http://code.google.com/p/hidemulator
I've not tried this code myself, but from what I can see, the script is reasonably easy to follow. It currently only supports the PS3's six-axis controller, but maybe you (or I, if I ever get the time) could adapt the Nokia project's Keyboard and Mouse routines into the Python script (or convert it to Java/Groovy, which is my ultimate goal ;-) ).
Cheers
Rich
It's not you are searching for but for Android devices.
AndroHid
http://code.google.com/p/androhid/
You need rooted device.
Unfortunately it doesn't work on my Nexus S - Cyanogen 9
btkbdd does this for Linux with Bluez. See: https://github.com/lkundrak/virtkbd/blob/master/btkbdd.pod