Cheap wireless audio transmitter and receiver for conference

Document created by Oleksandr Neuimin on Mar 5, 2017Last modified by Oleksandr Neuimin on Mar 6, 2017
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About this project

Wireless audio transmitter and receiver for conference based on NRF24L01 transceiver modules.

Wireless audio transmitter and receiver

 

Project info

Type : description on how I built my application / description of component or application usage 

Progress : I still have work to do 

Difficulty :  Intermediate

License :

The Team :

Who made this ?

Oleksandr NeuiminProject Developer

Oleksandr Neuimin 

deVAleksandr (Blog)

Things used in this project

Hardware components :

STM32F405RGT6STM32F405RGT6 1STM32F405RGT6 STMicroelectronics | Integrated Circuits (ICs) | DigiKey used in transmitter for ADC, FIR filter(optional), transmit audio data to radio module via SPI, LEDs and buttons control  
NRF24L01nrf24l01 pa lna with antenna1NRF24L01 Antenna | eBay used in transmitter
MAX9814ETD-TMAX9814ETD+T2MAX9814ETD+T Maxim Integrated | Integrated Circuits (ICs) | DigiKey a high-quality Microphone Amplifier IC with automatic gain control (AGC) and low-noise microphone bias. used in transmitter
AMS1117-3.3AMS1117-3.31
1A 3.3V Low Dropout Linear Regulator used in transmitter
lcd_module_hd44780HD447801
16-character × 2-line display
STM32F051C8T6

STM32F051C8T6

1STM32F051C8T6 STMicroelectronics | Integrated Circuits (ICs) | DigiKey 
used in receiver for digital-to-analog conversion and management modes
nrf24l01nRF24L0115pcs NRF24L01 + 2.4 GHz Wireless Module Mini Power Improved Board SMD Version | eBay 
used in receiver
mc34119mc3411915 Pcs MC34119DR Sop-8 Mc34119 34119 Low Power Audio Amplifier | eBay 
low power audio amplifier used in receiver
resistors, capacitors, leds, buttons, switchesmany
other electronic components

Hand tools and fabrication machines :

utility knife, pliers, cutters, soldering iron, drill.

Software Tools :

Keil uVision5, STM32CubeMX, Timer Calculator,  Altium Designer

 

Story

Hi. My name is Oleksandr. Currently I’m employed at National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”. I want to present you some project in which I used STM microcontrollers.

I decided show you this project which is not completed but is showing signs of life because I take a part in the competition “STM32 Fans Embedded World 2017 Contest”. If I win the 3D printer, I will make a present for my faculty which I graduated.  I think it will be very cool if students will be able to learn and do some things for their projects. If you like my idea please vote for my video "stm32-is-best-of-the-best" .

 

History of project

The idea of the project I was advised by my teacher movchanuk.andrey. His acquaintance provides equipment for a variety of conferences. And he wants to have a device which transmit and receive audio through a radio channel. The present-day devices use infrared channel. So I'm trying to realize this idea using inexpensive electronic components.

 

How does it work?

The device aim is to transmit sound from two channels, for example, transmit the voices of the two speakers who speak different languages. And on the receiver you can select and listen one channel of one of the speakers.

 

Transmitter

2 microphones connect to the transmitter board. The signal from the microphone is amplified using MAX9814ETD+T IC. After that, the signal goes to the ADC which is at STM32F405RGT6. I have implemented several FIR filters to remove some unwanted noise. They switch by the button on the transmitter board. STM32F405RGT6 and nrf24l01 module communicate via SPI.

It’s a first version of board and it looks not very nice. I had to put a shield plate on the radio module because interference was appeared.

transmitter

 

Receiver

The module nrf24l01 transmits the received signal to the MCU STM32F051C8T6. Next the samples are sent to the DAC which is available on the microcontroller. The analog signal passes reconstruction filter and amplifies by mc34119 IC for onward transmission to the headphones. Red leds are channel number indicators. The channels are switched by button. Reception RF signal Indicator (green led) and low battery indicator (yellow led) is also present. You can also adjust the volume by other buttons.

 

Latest version of receiver has been shown in this video "stm32-is-best-of-the-best" . 

 

First version of the receiver board you can see on the right side

receiver 1

Latest version of the receiver:

receiver 2

 

Future

I still work on my project. In the future I want to try to make casing to my devices on the 3D printer.

So if you like my project, please vote for my video  stm32-is-best-of-the-best .

It helps my idea - to give 3D printer for my faculty.

Thanks!

 

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