IOT: Wifi controlled Audio tone control

Internet of things is becoming a thing these days. Internet connected gadgets and appliance are becoming more common these days. The advantage is very obvious: you can control these devices using your smartphone with internet browser, specially made apps or with voice command using google assistant. One of the goal of this project is to create a tone control with bass, mid, treble and source selector that can be controlled via smartphone or laptop with an internet browser. You can also develop an app for this but I haven’t have time to do so.

About the Circuit

The heart of the circuit is the NODEMCU – a wifi module that can be programmed using arduino IDE. If you are already familiar with arduino then this can be easy for you. It is connected to a 1.44 inch tft lcd with ILI9163 driver. The preamp is based on TDA7419, this is a digitally controlled tone control via I2C. This features bass, mid, and treble controls with adjustable frequency. This also has a 7 band spectrum analyzer which is better than using an FFT on arduino. This makes it easier for the programming since you only need to read an analog pin directly rather than doing the FFT calculations on arduino which is a bit of a headache to do.

The TDA7419 is powered with 8V so an 8V regulator 7808 is needed. It is also used to power the Nodemcu for wider operating voltage (most nodemcu can only operate up to 10V only). 7808 regulator can operate up to 35V input voltage. You can also use any regulator as long as it has 8V output and a sufficient output current.

As you can see on the schematic, there is only 1 left GPIO on the nodemcu which is the D3. There is still GPIO9 and GPIO10 but many claims that they are not usable and are not recommended to use. This is the reason why I am not continuing this project with this kind of display. By using an I2C display, I can free up 5 GPIO’s that can be used for buttons.

About the Software

The software is developed using arduino IDE. Note that this is not very well developed, there are many rooms for improvement. I won’t be improving this software further because I decided to replace the display with an OLED I2C desplay. The reason is that the ILI9163 TFT display needs more GPIO and nodemcu has very limited GPIO. Using an I2C display will free up GPIO for other functions.

The device will not start the initialization of the TDA7419 without a wifi connection. Once it established a wifi connection, it will then go to initialization on the system. That is how I designed it, because it was just a quick programming for proof of concept only. Like what I said –  there are many room for improvements here. I just posted this project for those who want to have a quick start. For the next version of this project I will be using an OLED display to be able to use the 5 GPIO for buttons and other functions.


For the prototype, I used LM317 instead of the 7808 voltage regulator, because that’s what is readily available on my stocks. 🙂

demo: working. (Note: I accidentally cracked the LCD 🙁 )

The IP address is displayed on the LCD. This is entered on your web browser to access the controls. Take note that you have to connect on same wifi to be able to access the device.

Controlling with web browser

This is a simple webpage I made which can be improved further. The basic functions are there so you can use it as is if you prefer. There are many rooms for improvement here.


You can download the source code on the download page

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