Wireless digital audio transmission.

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#31 8268183 06 Jul 2010 22:38

PO. PO.

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Post #31
8268183 06 Jul 2010 22:38

Well, that's exactly what I'm aiming for, I just wanted to play with this cube, only with the availability and price so-so ... It's nice to know that he is at Kogitech's - somewhere else, in some easy-to-use modules?
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#32 8268207 06 Jul 2010 22:42

piotr_go piotr_go

DIY electronics designer

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Post #32
8268207 06 Jul 2010 22:42

I know where it is not , there is no A4TECH in similar micro receivers. They put something in there that I couldn't identify.
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#33 8268238 06 Jul 2010 22:49

PO. PO.

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Post #33
8268238 06 Jul 2010 22:49

piotr_go wrote:
I know where it is not , there is no A4TECH in similar micro receivers. They put something in there that I couldn't identify.

There are no old logitechs either, mx1000 etc. and in various older receivers for their mice and keyboards, I know because I was looking there some time ago both in the smaller and bookshelf mounts. In general, it is rather new equipment.
#34 8269033 07 Jul 2010 08:32

wilkolaski wilkolaski

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Post #34
8269033 07 Jul 2010 08:32

Okay, but how many of them do you need, i.e. you can not connect one or two capacitors?
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#35 8269582 07 Jul 2010 11:55

piotr_go piotr_go

DIY electronics designer

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Post #35
8269582 07 Jul 2010 11:55

What are all those thrifty?
I would make a single-sided PCB, 2 capacitors and then what? Something will not work and I will have to do it again, probably throwing out some of the elements.
I have a rule of how many power pins (not counting the mass) I try to give to the capacitors. So far, there have been no problems with the devices.
Besides, it's an audio device, what if I could hear "beats flying" in the speakers ?!
There must be decent filtration.
#36 8270817 07 Jul 2010 17:23

wilkolaski wilkolaski

Level 18

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Post #36
8270817 07 Jul 2010 17:23

Man, we got it wrong.
In no case do I blame you for the amount of them, I'm just curious why you gave them so many, i.e. what it gives.
In short, my question is out of pure curiosity.
#37 8270829 07 Jul 2010 17:25

piotr_go piotr_go

DIY electronics designer

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Post #37
8270829 07 Jul 2010 17:25

Less power disturbance.
#38 8272462 08 Jul 2010 01:01

piotr_go piotr_go

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Post #38
8272462 08 Jul 2010 01:01

I was able to get the nRF24LU1 + to run at full speed
I figured it out by accident.
Instead of sending data to it with usb_bulk_write (), I loaded the usbserial driver and sent the data as if to a serial port.
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#39 8279817 10 Jul 2010 14:13

wojtii77 wojtii77

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Post #39
8279817 10 Jul 2010 14:13

piotr_go wrote:
9m, I still did not check.
I also checked whether it would break through 2 floors. When I set the antennas properly, it worked.

From what I remember, an ordinary FM transmitter connected to a 12V car socket had a range of 50 m + 2 walls behind which the radio was set to the appropriate frequency.
#40 8279866 10 Jul 2010 14:31

Mat_91 Mat_91

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Post #40
8279866 10 Jul 2010 14:31

wojtii77 wrote:
From what I remember, an ordinary FM transmitter connected to a 12V car socket had a range of 50 m + 2 walls behind which the radio was set to the appropriate frequency.
But an ordinary FM transmitter works at a completely different frequency and with a different power.
piotr_go wrote:

I was able to get the nRF24LU1 + to run at full speed Smile
I figured it out by accident.
Instead of sending data to it with usb_bulk_write (), I loaded the usbserial driver and sent the data as if to a serial port.
So full performance from a micro transmitter?;> How about the range of this small contraption?
#41 8281663 11 Jul 2010 10:17

piotr_go piotr_go

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Post #41
8281663 11 Jul 2010 10:17

Full performance. Range - poorly, when you walk between it and the receiver, it cuts, you would have to give another antenna or somehow turn it by 90 degrees because then it cuts much less often.
#42 8282459 11 Jul 2010 19:35

nusch nusch

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Post #42
8282459 11 Jul 2010 19:35

What about logitech unifying can be done so as not to lose basic functions, i.e. to have a mouse, keyboard and sound, or has your program completely replaced the standard logitech?
#43 8282476 11 Jul 2010 19:44

piotr_go piotr_go

DIY electronics designer

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Post #43
8282476 11 Jul 2010 19:44

Completely, I think the logitech people were intelligent enough to protect their soft from being read. (I did not have the opportunity to check very much because I tested the programmer and I could delete something first)
#44 8286579 13 Jul 2010 07:58

irekr irekr

VIP Meritorious for electroda.pl

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Post #44
8286579 13 Jul 2010 07:58

Another question.
Would you undertake a similar set but:
1. In the 5 GHz band
2. With signal input / output in AES EBU standard in layer 1 and 2 (448 kbs DSR5.1), and / or optional Spdif in classic stereo.
3. In another licensed band.
greetings
irek
#45 8287168 13 Jul 2010 12:04

piotr_go piotr_go

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Post #45
8287168 13 Jul 2010 12:04

Getting nRF in our beautiful country is almost a miracle, let alone something faster on a less popular band
nRF was the fastest I found (370kbps checked by me).
#46 8291213 14 Jul 2010 14:33

stgw stgw

Level 2

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Post #46
8291213 14 Jul 2010 14:33

Hello, is there any software that supports the transmitter under Windows, or only under Linux?
#47 8291351 14 Jul 2010 15:10

piotr_go piotr_go

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Post #47
8291351 14 Jul 2010 15:10

So far I have only written the output module for PulseAudio. I have no plans for Windows drivers.
At first, I was thinking about emulating some standard audio device in the transmitter so that it could be used with any system. Unfortunately, the processor is a bit weak to encode MP3
#48 8309115 19 Jul 2010 19:43

nairamk nairamk

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Post #48
8309115 19 Jul 2010 19:43

And what is the time shift in audio reception?

I won't believe he's gone.
- sampling, compression to mpeg, transmission, decompression and playback.

It must take a while ...

Is it suitable for more than music?

Why is he asking such a question?

Because I once bought a Motorola A2DP set. The set consists of a small soap dish with audio inputs and a bluetooth module, and of course headphones.

... what was my disappointment when it turned out that the time shift of the audio signal completely EXCLUDES such a solution for watching movies. It's just annoying to see sooner that they are talking than the sound reaches your ears.

As a result, the set is completely unused :(

How is it with you?
#49 8310001 19 Jul 2010 22:51

piotr_go piotr_go

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Post #49
8310001 19 Jul 2010 22:51

The transmission delay is, of course, but the latency in the PulseAudio output module is adjusted so that the image matches the sound. If anyone wanted, it can even be set so that the sound is ahead of the picture.
#50 8369847 06 Aug 2010 02:46

uzi18 uzi18

Level 24

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Post #50
8369847 06 Aug 2010 02:46

How Much Can I Pull Without Compression?
Maybe some simple compression algorithm should be used.
#51 8370536 06 Aug 2010 11:52

piotr_go piotr_go

DIY electronics designer

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Post #51
8370536 06 Aug 2010 11:52

And MPEG is what if not lossy compression?
#52 8460708 31 Aug 2010 16:57

piotr_go piotr_go

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Post #52
8460708 31 Aug 2010 16:57

New version added at the end of the first post.
#53 8492900 09 Sep 2010 17:33

Anonymous Anonymous

Anonymous

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Post #53
8492900 09 Sep 2010 17:33

It's great after the picture itself, I can see that I would like to have something like that

Added after 15 [minutes]:

What if he would like to transfer audio only from the audio back channel in AC3 format or other dolby codec or Direct X surround sound from the sound card
#54 8495332 10 Sep 2010 10:20

piotr_go piotr_go

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Post #54
8495332 10 Sep 2010 10:20

2 channels from 5.1 to play on another device? Although I have never tried it, I think PulseAudio does. You would have to look in the manual.
For a full 5.1 transmission, the receiver is too weak (and obviously - stereo DAC).
#55 8875159 16 Dec 2010 11:59

NDorian NDorian

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Post #55
8875159 16 Dec 2010 11:59

to: piotr_go

Hello. Saw your project is really cool!
Can I ask you for a little help?
I'm trying to do something similar, or even just run the radio transmission. There I have SAM7-EX256 with a module MOD-NRF24L which connects via UEXT to SPI0 (CS0). I am suffering for about a week, I can not configure the SPI to work with nRF24. Taken as a basis for several projects including "STM32-103STK" and "LPC-P2148 demo code. " I can not understand or I'm such a fool, and my hands are curves or something on the board.
Could you show how to make the setting for SPI nRF24 on SAM7?

my e-mail address:
night.dorian @ gmail.com

Thanks in advance!
#56 8875213 16 Dec 2010 12:22

piotr_go piotr_go

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Post #56
8875213 16 Dec 2010 12:22

spi.c:
[code:1:1f07950116]//SPI_MR bits
#define PCS3 0x80000
#define PCS2 0x40000
#define PCS1 0x20000
#define PCS0 0x10000
#define LLB 0x00080
#define MODFDIS 0x00010
#define FDIV 0x00008
#define PCSDEC 0x00004
#define PS 0x00002
#define MSTR 0x00001

//SPI_CR bits
#define LASTXFER 0x1000000
#define SWRST 0x0000080
#define SPIDIS 0x0000002
#define SPIEN 0x0000001

//SPI_CSRx bits
#define DLYBCT 24
#define DLYBS 16
#define SCBR 8
#define BITS 0x10
#define CSAAT 0x8
#define NCPHA 0x2
#define CPOL 0x1

//PIOA peripheral pins
#define MISO 1
#57 10007637 09 Oct 2011 05:47

mpx-fm mpx-fm

Level 19
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Post #57
10007637 09 Oct 2011 05:47

stgw wrote:
Hello, is there any software that supports the transmitter under Windows, or only under Linux?

is pulseaudio-0.9.6-1.win32.zip
(911 KiB) but you have to ask the author to let the author test - I don't have the equipment
http://www.cendio.com/pulseaudio/

you can also yes (I did not check) Link-Google Translate Link

and so on: via http://sourceforge.net/projects/portableubuntu/
Code: text Expand Select all Copy to clipboard
Portable Ubuntu for Windows Przenośne Ubuntu dla Windows jest sytemem Ubuntu działającym jak aplikacja Windows. System ten został zbudowany przy użyciu jądra Colinux, X serwera Xming, i serwera Pulseaudio dla Windows. Przenośne Ubuntu dla Windows jest przydatnym narzędziem, jeśli musisz przenieść się na stanowisko z komputerem na którym jest zainstalowany system Windows.
Link
#58 10008786 09 Oct 2011 14:33

piotr_go piotr_go

DIY electronics designer

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Post #58
10008786 09 Oct 2011 14:33

Wish it were that simple...
Unfortunately, PulseAudio has to be compiled with modifications yourself. For this you need to add the LAME library and probably some USB driver.
This driver can be the biggest problem. Under Linux, you can bypass it and communicate directly with the endpoints of the device.
#59 10014750 11 Oct 2011 04:51

mpx-fm mpx-fm

Level 19

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Post #59
10014750 11 Oct 2011 04:51

and it's not better to think about something cheaper than nrf2401 + AT91SAM, for example on STM32W108
it would be cheaper several times
I also saw prefabs from Chinoli. and from some Italian company Link Link

or let me remember- hmmm ...
I do not remember at the moment, but there is no new integrated scalak - 2.4GHz transceiver for audio transmission
I will look for it in my free time, I only remember that its cost was close to nrf2401, as far as I remember, it was spdif and the analog could be sent with it
#60 10015508 11 Oct 2011 13:05

piotr_go piotr_go

DIY electronics designer

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Post #60
10015508 11 Oct 2011 13:05

STM32W108 is not suitable because it has:
- too low transmission speed
- too low core speed
- not enough frame
- no i2s
and the transmitter is not suitable because there is no USB.

A ready scalak (also from the Nordic company) is of course and was even at the time when I was designing this circuit, but I can't buy it.
The NRF24L01 is quite popular for that. Even if you can not buy it, there are a lot of devices from which it can be disassembled.

The project was to be an introduction to the construction of stereo headphones with a microphone.
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Topic summary

The discussion revolves around a wireless digital audio transmission system utilizing Nordic Semiconductor's NRF24L01 module operating in the 2.4GHz band. The transmitter is based on the AT91SAM7S64 microcontroller, employing the LAME MP3 Encoder for audio compression at a bitrate of 320kbps. The system allows for audio redirection to wireless speakers via PulseAudio, with adjustable buffering delay. The receiver uses the AT91SAM7S512 microcontroller and the Helix decoder, with TDA1543 as the DAC. Users inquire about range, costs, potential production, and compatibility with existing devices, while the author shares insights on component sourcing, programming challenges, and latency management. The conversation also touches on alternatives like Bluetooth A2DP and the feasibility of using different microcontrollers for similar applications.
Summary generated by the language model.

FAQ

TL;DR: DIY 2.4 GHz audio link streams 320 kbps MP3 up to 9 m indoors; “The latency can be set freely” [Elektroda, piotr_go, post #8264643] Range and delay are user-tuneable via PulseAudio on Linux [Elektroda, piotr_go, post #8262996]

Why it matters: Makers can build low-cost wireless speakers that beat unstable Bluetooth A2DP in sound quality and control.

Quick Facts

• Link speed: ~400 kbps raw, 320 kbps payload using NRF24L01+ with ACK enabled [Elektroda, piotr_go, post #8262444]
• Verified range: 9 m LOS; penetrates two floors with antenna alignment [Elektroda, piotr_go, post #8262996]
• Receiver draw: ≈60 mA playing, 14 mA idle [Elektroda, piotr_go, post #8262444]
• BOM cost: PLN 150–200 per Tx/Rx pair (≈€35–45) in small runs [Elektroda, piotr_go, post #8263100]
• Tuneable channels: any 2 MHz slot between 2.400–2.5 GHz to dodge Wi-Fi [Elektroda, piotr_go, post #8263220]

What hardware makes this 2.4 GHz audio link work?

The transmitter uses an AT91SAM7S64 MCU driving an NRF24L01+ transceiver; audio is pre-encoded to 320 kbps MP3 on the PC. The receiver runs an AT91SAM7S512, decodes via the Helix MP3 library, and outputs through a TDA1543 or CS4344 DAC [Elektroda, piotr_go, post #8262444]

How far can the signal travel in real homes?

Open-space reach is about 9 m; with antennas aligned it played through two concrete floors. Mis-alignment or walking between devices can cause dropouts, especially with the micro-sized transmitter [Elektroda, piotr_go, #8262996; #8281663].

Will it clash with my 2.4 GHz Wi-Fi router?

You can program any 2 MHz channel inside 2.400–2.500 GHz, so selecting an idle slot avoids Wi-Fi overlap [Elektroda, piotr_go, post #8263220]

Is latency noticeable when watching movies?

No. PulseAudio lets you set buffer delay so audio matches video; users can even advance sound ahead of picture if desired [Elektroda, piotr_go, #8264643; #8310001].

What power supply do I need for the receiver?

Expect roughly 60 mA during playback and 14 mA while waiting for packets, so a 3.3 V source with ≥100 mA headroom is safe [Elektroda, piotr_go, post #8262444]

How much will a DIY set cost to build?

Prototype parts sourced from multiple vendors cost PLN 150–200 per pair. Bulk buying or PCB panelisation lowers the figure [Elektroda, piotr_go, #8263100; #8263180].

Can I etch a single-sided PCB to save money?

Not advised. Nordic’s layout guide calls for a solid ground plane and plenty of vias; single-layer boards hurt RF performance [Elektroda, piotr_go, post #8263270]

How do I turn a Logitech Unifying dongle into a micro transmitter?

Solder an external antenna to the nRF24LU1+ inside the dongle.
Flash new firmware via SPI using an ATmega-based programmer [Elektroda, piotr_go, post #8265434]
Load a usbserial driver and stream audio as if to /dev/ttyUSBx [Elektroda, piotr_go, post #8272462]

Why skip Bluetooth A2DP modules that cost only PLN 70?

The author reports frequent audio dropouts and lower SBC codec quality, whereas LAME-encoded MP3 remains stable at 320 kbps [Elektroda, piotr_go, post #8265434]

Is there Windows software, or only Linux support?

Only a custom PulseAudio output module for Linux exists. Porting to Windows would need recompiling PulseAudio with LAME and writing a USB endpoint driver [Elektroda, piotr_go, #8291351; #10008786].

Can the system transmit 5.1 surround sound?

No. The receiver’s MCU and stereo DAC limit throughput; PulseAudio can down-mix 5.1 to two channels, but full 5.1 exceeds processing and bandwidth limits [Elektroda, piotr_go, post #8495332]

What’s an edge-case failure I should plan for?

The micro-transmitter stutters when a person blocks the path because its PCB antenna lacks gain. Mounting a quarter-wave whip or rotating 90° reduces the issue [Elektroda, piotr_go, post #8281663]

How many decoupling capacitors are really necessary?

Place a 100 nF ceramic at every Vcc pin; this lowers supply ripple and prevents audible “beats” in audio output [Elektroda, piotr_go, post #8269582] "Less disturbance equals cleaner sound," notes the designer.

Does the NRF24L01+ support lossless audio if I skip MP3?

Practical payload is ~370 kbps after overhead. CD-quality stereo PCM needs 1.4 Mbps, so compression (MP3, AAC, or ADPCM) is mandatory unless you drop sample rate or channels [Elektroda, piotr_go, post #8369847]