How to make Arduino based digital audio system?

#Arduino Project

There are multiple music systems available in market, but lets make our own digital music system using Arduino nano board and TDA7439 which is three band four channel digital audio processor. The core of this system is off course the Ardunio Nano which is programmed to take inputs from rotary encoder and tactile switches and control Radio module, BT Module and sound processor IC TDA7439 and display results on 0.96inch OLED.

Power amplifier is not built here, so external power amplifier of your choice can be connected to the output of this processor.

Here is the view of assembled main board, radio board and front panel.

Watch out the video to see the system fully functioning. 

Let us see the features of this system:

•  It has four input channels
        CH-1 for Bluetooth Module

        CH-2 for Radio (with fixed station frequencies)

        CH-3 for Auxiliary Input-1

        CH-4 for Auxiliary Input-2

•  Four Switches to

        Select Input Channels

        Mute

        Select Next Radio Station

        Select Preset Sound Equalizer Settings

 •  Rotary Encoder to 

       Change Volume Level

       Change Bass Level

       Change Mid Level

       Change Treble Level

       Adjust stereo balance level

  •  OLED to display all the selected values above

I have done few modifications in TEA5767 foot print and rotary encoder board to mount them as per my need.

- Drill hole in TEA5767 foot prints and solder 4pin 2.0mm male headers and solder TEA5767 module on top side of PCB with header pins carefully

- Rotary encoder comes with 5pin right angled male header which I replaced with 5pin simple male header to fit in front panel board. Also used general purpose PCB to extend the rotary encoder physical position that is optional.

I have used rotary encoder of below pin configuration. You can use any encoder module compatible to this. (Image taken from https://www.electronicscomp.com/)

Important Note: Please solder one wire directly from MH-M18 BT module ground pin to main board ground terminal to reduce noise during Bluetooth mode.

There are four pins on side of BT module out of which one pin is gnd, one is VCC and rest two unknown pins. Use the ground pin as shown in this image. I have connected it to pin-4 of TDA7439 IC.

For Connecting the 14pin cable to main board refer to below diagram and follow pin number labels in yellow.

While designing the mail PCB my idea was different, I dint though of making a front panel. Later I decided to make a perfect audio system hence front panel was designed and these additional connections to different parts of PCB is required rather than having 14pin single line connections for all wires.

Here is the connection diagram:

Also refer below the pin connection of Radio board which will help to plug correctly in main board. Polarities are marked looking at bottom of board.

Note: After powering ON the system, it initializes the radio board and OLED. If radio board is not plugged in the main board, Arduino may keep waiting for feedback from radio and may get stuck there.

Use proper length antenna cable to connect to radio board for better reception.

You can change the radio frequency set points in program based on available frequencies in your city or country.

Here are the schematic of all three different parts of complete system.

Main Board

Front Panel

Radio Board

Here is the code for Arduino that need to be programmed in Arduino board through Arduino IDE.

#include <EEPROM.h> #include <Wire.h> #include <Adafruit_GFX.h> #include <Adafruit_SSD1306.h> #include <TDA7439.h> #include <TEA5767.h> TDA7439 equ; TEA5767 radio = TEA5767(); Adafruit_SSD1306 display(128, 64, &Wire, 4); float freq[8]= {91.1, 93.5, 98.3, 100.7, 101.6, 104.0, 105.6, 107.2}; //Min freq 88Mhz float curr_freq; char x[4]; int counter = -1; int currentStateCLK; int lastStateCLK; int stn_cnt=0; unsigned long scr_timeout = 0, lastButtonPress = 0, mem_write_time = 0; int control = 0; //0 - for volume, 1 for bass, 2 for mid, 3 for treble, 4 for bal int vol = 0, bass = 7, mid = 7, tre = 7, bal = 0, input = 1, gain=7, BT_PWRstate = 0, mute_state = 0; //mute_state = 0-unmute, 1-mute int minlvl = 14, level=0; //set min level - 14 int preset_eq = 0; int ratt=0, latt=0; // Rotary Encoder Inputs #define CLK 3 #define DT 2 #define SW 4 //BT pwr contrl pin #define BT_PWR 9 //keyboard inputs #define mut 5 #define next 6 #define select 7 #define equalizer 8 void setup() { Serial.begin(9600); Wire.begin(); if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { Serial.println(F("SSD1306 allocation failed")); for(;;); // Don't proceed, loop forever } display.clearDisplay(); display.display(); display.setTextSize(1); display.setTextColor(WHITE); display.fillRoundRect(2, 5, 95, 3, 0, WHITE); display.fillRoundRect(10, 10, 87, 3, 0, WHITE); display.fillRoundRect(18, 15, 79, 3, 0, WHITE); display.drawRect(97, 2, 28, 20, WHITE); display.setCursor(3,25); display.print(F("Digital Audio System")); display.setCursor(100,5); display.setTextSize(2); display.print(F("DS")); display.fillRoundRect(2, 36, 120, 25, 3, WHITE); display.setTextColor(BLACK); display.setTextSize(2); display.setCursor(10,41); display.print(F("BT FM AUX")); display.display(); display.setTextColor(WHITE); display.setFont(); //return to default font pinMode(BT_PWR, OUTPUT); // Set encoder pins as inputs pinMode(CLK,INPUT); pinMode(DT,INPUT); pinMode(SW, INPUT_PULLUP); // Read the initial state of CLK lastStateCLK = digitalRead(CLK); eeprom_read(); //read previous store parameters radio.init(14); digitalWrite(BT_PWR, HIGH);delay(20); digitalWrite(BT_PWR, LOW); //switch OFF BT once delay (100); digitalWrite(BT_PWR, HIGH); BT_PWRstate=0; equ.setInput(input); // 1 to 4 equ.inputGain(10); equ.setVolume(vol); // 0 to 48 ( 0 is mute) equ.setSnd(bass-7,1); //bass level -7 to +7 , 1 - Bass | 2 - Mids | 3 - Trebble equ.setSnd(mid-7,2); //mid level equ.setSnd(tre-7,3); //treble level if (bal==0) { ratt=bal; latt=bal; } if (bal<0) { ratt = 0; latt = -bal; } if (bal>0) { ratt = bal; latt = 0; } equ.spkAtt(ratt, latt); if (input == 2) { radio.setStandby(0); delay(20); radio.setFrequency(freq[stn_cnt]); } } void loop() { currentStateCLK = digitalRead(CLK); if (currentStateCLK != lastStateCLK && currentStateCLK == 1){ scr_timeout = millis(); // If the DT state is different than the CLK state then // the encoder is rotating CCW so decrement if (digitalRead(DT) != currentStateCLK) { if (control==0){ vol--; volume(); } if (control==1){ bass--; basscntrl();} if (control==2){ mid--; midrange(); } if (control==3){ tre--; treble(); } if (control==4){ bal=bal-4;; balance(); } if (control==5) { input--; inputsrc(); } } else { if (control==0){ vol++; volume(); } if (control==1){ bass++; basscntrl();} if (control==2){ mid++; midrange(); } if (control==3){ tre++; treble(); } if (control==4){ bal=bal+4; balance(); } if (control==5) { input++; inputsrc(); } } } lastStateCLK = currentStateCLK; if (digitalRead(SW) == LOW) { //rotary switch status if (millis() - lastButtonPress > 50) { scr_timeout = millis(); control = control + 1; if (control>4) {control = 0;} } lastButtonPress = millis(); if (control==0){ volume(); } if (control==1){ basscntrl(); } if (control==2){ midrange(); } if (control==3){ treble(); } if (control==4){ balance(); } } if (input!=1 && BT_PWRstate==1) //switch off BT if not a selected source { digitalWrite(BT_PWR, HIGH);delay(100); digitalWrite(BT_PWR, LOW); delay (100); digitalWrite(BT_PWR, HIGH); BT_PWRstate=0; } if (input==1 && BT_PWRstate==0) //switch on BT if it is selected source and is off { digitalWrite(BT_PWR, HIGH);delay(100); digitalWrite(BT_PWR, LOW); delay (100); digitalWrite(BT_PWR, HIGH); BT_PWRstate=1; } if (input!= 2) { radio.setStandby(1); }//mute radio if not in use if (digitalRead(next) == LOW) { //next button pressed //if 50ms have passed since last LOW pulse, it means that the //button has been pressed, released and pressed again if (millis() - lastButtonPress > 100) { scr_timeout = millis(); if (input == 2) { stn_cnt++; if (stn_cnt>7) { stn_cnt=0; } radio.setFrequency(freq[stn_cnt]); delay(20); curr_freq = radio.getFrequency(); fm_display(); } } lastButtonPress = millis(); } if (digitalRead(equalizer) == LOW) { //peset button pressed if (millis() - lastButtonPress > 100) { scr_timeout = millis(); preset_eq = preset_eq + 1; //0-Flat, 1-Rock, 2- Classic, 3- Pop, 4- Bass boost, 5- Treble boost if (preset_eq > 5) { preset_eq = 0; } preset_sound(); // call preset audio settings } lastButtonPress = millis(); } if (digitalRead(mut) == LOW) { //mute_state: 0 - unmute , 1 - Mute if (millis() - lastButtonPress > 100) { scr_timeout = millis()+5000; if (mute_state == 0) { //mute system equ.mute(); mute_state = 1; } else if (mute_state == 1) { //unmute system equ.setVolume(vol); mute_state = 0; } } lastButtonPress = millis(); } if (digitalRead(select) == LOW) { //mute_state: 0 - unmute , 1 - Mute if (millis() - lastButtonPress > 100) { scr_timeout = millis(); input++; if (input > 4) { input = 1; } inputsrc(); if (input == 2) { radio.setStandby(0); radio.setFrequency(freq[stn_cnt]); } } // Remember last button press event lastButtonPress = millis(); } if (millis() - scr_timeout > 5000) { defaultscreen(); scr_timeout = millis();} if (millis() - mem_write_time > 30000) { eeprom_update(); //update parameters to EEPROM after every 60sec mem_write_time = millis(); } disp_mute(); } void drawProgressbar(int x,int y, int width,int height, int progress) { progress = progress > 100 ? 100 : progress; // set the progress value to 100 progress = progress < 0 ? 0 :progress; // start the counting to 0-100 float bar = ((float)(width-1) / 100) * progress; display.drawRect(x, y, width, height, WHITE); display.fillRect(x+2, y+2, bar , height-4, WHITE); } void defaultscreen(){ control = 0; //reset control to volume control i.e. default display.clearDisplay(); display.setTextSize(1); display.setCursor(0,10); display.print(F("PLAYING")); display.setCursor(0,30); display.setTextSize(2); if (input==1) { display.print(F("Bluetooth")); disp_mute(); preset_sound();} //preset_sound(); else if (input==2) { fm_display(); disp_mute(); preset_sound(); } else if (input==3) { display.print(F("Aux-1")); disp_mute(); preset_sound();} else if (input==4) { display.print(F("Aux-2"));disp_mute(); preset_sound();} display.display(); } void volume(){ if (vol>=48) { vol=48; } if (vol<=0) { vol = 0; } mute_state=0; equ.setVolume(vol); // 0 to 48 ( 0 is mute) display.clearDisplay(); display.setTextSize(2); display.setCursor(0,10); //display.setTextColor(WHITE); display.print(F("VOL")); display.setTextSize(3); display.setCursor(50,10); display.print(vol); display.setFont(); drawProgressbar(0,40,120,15, vol * 2.05 ); display.display(); } void basscntrl(){ if (bass>=14) { bass=14; } if (bass<=0) { bass = 0; } equ.setSnd(bass-7,1); //bass level -7 to +7 , 1 - Bass | 2 - Mids | 3 - Trebble display.clearDisplay(); display.setTextSize(2); display.setCursor(0,10); display.print(F("BAS")); display.setTextSize(3); display.setCursor(50,10); display.print(bass); drawProgressbar(0,40,120,15, bass * 7.07 ); display.display(); } void midrange(){ if (mid>=14) { mid=14; } if (mid<=0) { mid = 0; } equ.setSnd(mid-7,2); //mid level display.clearDisplay(); display.setTextSize(2); display.setCursor(0,10); display.print(F("MID")); display.setCursor(50,10); display.setTextSize(3); display.print(mid); drawProgressbar(0,40,120,15, mid * 7.07 ); display.display(); } void treble(){ if (tre>=14) { tre=14; } if (tre<=0) { tre = 0; } equ.setSnd(tre-7,3); //treble level display.clearDisplay(); display.setTextSize(2); display.setCursor(0,10); display.print(F("TRE")); display.setTextSize(3); display.setCursor(50,10); display.print(tre); drawProgressbar(0,40,120,15, tre * 7.07 ); display.display(); } void balance(){ if (bal>=80) { bal=80; } if (bal<=-80) { bal = -80; } if (bal==0) { ratt=bal; latt=bal; } if (bal<0) { ratt = 0; latt = -bal; } if (bal>0) { ratt = bal; latt = 0; } equ.spkAtt(ratt, latt); display.clearDisplay(); display.setTextSize(2); display.setCursor(0,10); display.print(F("BAL")); display.setTextSize(3); display.setCursor(50,10); display.print(bal); display.print (F("%")); display.drawRect(0, 40, 128, 15, WHITE); display.drawRect(61, 38, 5, 19, WHITE); display.fillRect(62+bal/1.4, 38, 4 , 19, WHITE); display.display(); } void inputsrc() { if(input<1) { input = 4; } if (input>4) { input = 1; } equ.setInput(input); // 1 to 4 display.clearDisplay(); display.setTextSize(2); display.setCursor(0,10); display.print(F("Source:")); display.print(input); display.setCursor(0,30); display.setTextSize(2); if (input==1) { display.print(F("Bluetooth")); } else if (input==2) { display.print(F("FM Radio")); radio.setStandby(0); delay(20); } else if (input==3) { display.print(F("Aux-1")); } else if (input==4) { display.print(F("Aux-2")); } display.display(); } void fm_display() { display.clearDisplay(); level = radio.getSignalLevel(); //Get Signal Level delay(100); //Serial.print ("Signal Level: "); //Serial.println(level); fm_signal(); display.setTextSize(1); display.setTextColor(WHITE); display.setCursor(0,0); display.fillTriangle (102, 11, 94,4, 110,4, WHITE); display.fillRect(101,10,3,8,WHITE); display.setTextColor(WHITE); display.setTextSize(1); display.setCursor(5, 5); display.print(F("Playing")); display.setTextSize(2); display.print(F(" FM")); display.setCursor(0,30); display.setTextSize(3); dtostrf(radio.getFrequency (), 4, 1, x); //round dislay frequency to 1 digit if (radio.getFrequency() < 100) { display.setCursor(18,30); } else { display.setCursor(0,30); } display.print(x); display.setCursor(90,30); display.setTextSize(1); display.print(F("MHz")); display.setCursor(100,45); display.print(stn_cnt+1); display.display(); } void fm_signal() { if (level>=0 && level<=2) {for (short j=0; j<1; j++) { display.drawRect(110+(j*3), 15-(j*2), 2, 3+(j*2), WHITE); } for (short j=1; j<5; j++) { display.drawRect(110+(j*3), 20-(j*2), 2, 3+(j*2), BLACK); }} if (level>=3 && level<=5) {for (short j=0; j<2; j++) { display.drawRect(110+(j*3), 15-(j*2), 2, 3+(j*2), WHITE); } for (short j=2; j<5; j++) { display.drawRect(110+(j*3), 20-(j*2), 2, 3+(j*2), BLACK); }} if (level>=6 && level<=9) {for (short j=0; j<3; j++) { display.drawRect(110+(j*3), 15-(j*2), 2, 3+(j*2), WHITE); } for (short j=3; j<5; j++) { display.drawRect(110+(j*3), 20-(j*2), 2, 3+(j*2), BLACK); }} if (level>=10 && level<=12) {for (short j=0; j<4; j++) { display.drawRect(110+(j*3), 15-(j*2), 2, 3+(j*2), WHITE); } for (short j=4; j<5; j++) { display.drawRect(110+(j*3), 20-(j*2), 2, 3+(j*2), BLACK); }} if (level>=13 && level<=15) {for (short j=0; j<5; j++) { display.drawRect(110+(j*3), 15-(j*2), 2, 3+(j*2), WHITE); } } } void disp_mute () { if (mute_state==1) { display.setTextSize(1); display.setCursor(10,55); display.print(F("MUTE")); } if (mute_state==0) { display.setTextSize(1); display.setCursor(10,55); display.print(F("")); } } void preset_sound() //0-Flat, 1-Rock, 2- Classic, 3- Pop, 4- Bass boost { display.fillRoundRect(68, 55, 45, 9, 1, WHITE); display.setTextSize(1); display.setTextColor(BLACK); switch (preset_eq) { case 0: display.setCursor(80, 56); display.print(F("FLAT")); bass = 7; mid = 7; tre = 7; break; case 1: display.setCursor(80, 56); display.print(F("ROCK")); bass = 10; mid = 7; tre = 10; break; case 2: display.setCursor(70, 56); display.print(F("CLASSIC")); bass = 7; mid = 10; tre = 7; break; case 3: display.setCursor(82, 56); display.print(F("POP")); bass = 3; mid = 10; tre = 3; break; case 4: display.setCursor(70, 56); display.print(F("Hi-BASS")); bass = 14; mid = 7; tre = 7; break; case 5: display.setCursor(70, 56); display.print(F("Hi-TREB")); bass = 7; mid = 7; tre = 14; break; } equ.setSnd(bass-7,1); equ.setSnd(mid-7,2); equ.setSnd(tre-7,3); display.display(); display.setTextColor(WHITE); //restore default text color } void eeprom_update() { EEPROM.update(0, input); EEPROM.update(1, vol); EEPROM.update(2, bass); EEPROM.update(3, tre); EEPROM.update(4, mid); EEPROM.update(5, bal); EEPROM.update(6, preset_eq); EEPROM.update(7, stn_cnt); EEPROM.update(8, mute_state); } void eeprom_read() { input = EEPROM.read(0); vol = EEPROM.read(1); bass = EEPROM.read(2); tre = EEPROM.read(3); mid = EEPROM.read(4); bal = EEPROM.read(5); preset_eq = EEPROM.read(6); stn_cnt = EEPROM.read(7); mute_state = EEPROM.read(8); //set some default values if EEPROM is empty for first run if (vol > 48) { vol = 10; } if (input > 4) { input = 1; } if (bass > 14) { bass = 7; } if (tre > 14) { tre = 7; } if (mid > 14) { mid = 7; } if (bal > 80) { bal = 0; } if (preset_eq > 5) { preset_eq = 0; } if (stn_cnt > 7) { stn_cnt = 0; } if (mute_state > 1) { mute_state = 0; } }

Part List (Main Board):

Component	Part#	Value	Quantity
Capacitor	C1, C15, C16, C17, C23, C24, C25, C26	100n / 25V	08 nos.
	C2, C3	1n / 25V	02 nos.
	C4 to C11	470n / 25V	08 nos.
	C12, C13, C19, C20	2.2uf / 25V	04 nos.
	C14	10uf / 25V	01 no.
	C15 to C17, C23 to C26	100nf / 25V	07 nos.
	C18	100uf / 25V	01 no.
	C21, C28	18nf / 25V	02 nos.
	C22, C27	22nf / 25V	02 nos.
	C22, C27	22nf / 25V	02 nos.
	C29, C30	5.6nf / 25V	02 nos.
	C31	1000uf / 25V	01 nos.
Diode	D1 to D4	1N4001/td>	04 nos.
LED 3mm (Optional)	D5, D6	Red or Green	02 nos.
Resistor	R1, R2	100 Ohms, 1/4Watt	02 nos.
	R3, R4, R10 to R15	10 KOhms, 1/4Watt	08 nos.
	R5, R8	2.7 KOhms, 1/4Watt	02nos.
	R6, R7	5.6 KOhms, 1/4Watt	02nos.
	R16	1 KOhms, 1/4Watt	01 no.
	R17	330 Ohms, 1/4Watt	01 no.
Jump Wires	J4 to J16	As Per Size	13 nos.
Female Header	For Arduino Nano	15pin, 2.54mm	02 nos.
	SL2 (for Radio Board)	6pin, 2.54mm	01 nos.
Male Header	SL1 (for 12V Supply)	2 Pin, 2.54mm	01no.
	For Audio Output	3 Pin, 2.54mm	01no.
Arduino	Ardunio Nano Module		01no.
ICs	U1	LM7809	01no.
	U2	LM7805	01no.
	SDIP30	TDA7439	01no.

Part List (Front Panel):

Component	Part#	Value	Quantity
Capacitor	C1	10uf / 16V	01 no.
	C2	100n / 25V	01 no.
	C3	470uf / 16V	01 no.
Jumpers	J1 to J5	As Per Size	04 nos.
LED	LED1	5mm Red	01 no.
BT Module	MH-M18	MH-M18	01 no.
Female Header	For MH-M18	06pin 2.54mm	01 no.
	For OLED	04pin 2.54mm	01 no.
Male Header	For Connecting Main Board	14pin 2.54mm Right Angled with 14 Pin RMC - Polarized Header Wire/Cable - Relimate Connector	01 no.
	For Rotary Encoder	05pin 2.54mm	01 no.
Resistor	R1	330 Ohms 1/4 Watt	01 no.
OLED	0.96 inch 4Pin 128 x 64 White OLED	128 X 64 Pixel	01 no.
Rotary Encoder	From electronicscomp.com	Product Code: EC-2176	01 no.
Switch	S1 to S4	12mm - 4 pin - Tactile/Micro Switch	04 nos.

Part List (Radio Board):

Component	Part#	Value	Quantity
Module	Radio Module	TEA5767	01 no.
Male Header	SL1	06 Pin 2.54mm Right Angled	01 no.
	For TEA5767 Board	04 Pin 2.0mm	02 nos.
IC	U1	LM1117	01 no.
Capacitor	C1, C2	100nf 16V	02 nos.

I haven't added IR remote functionality as OLED and IR remote libraries create issue. Still I will try to add remote function to it by some other way soon.

Click here to download Eagle board files for making pcb.

Till then enjoy the music.

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