Mirko Pavleski
NORTH MACEDONIA • + Follow
Components
|
|
Espressif ESP32 Development Board |
x 2 | |
|
|
GC9A01 Round Display |
x 2 | |
|
|
1N4007TWGMC
|
x 2 | |
|
|
Resistor 10k ohm |
x 2 | |
|
|
Resistor 220 ohm |
x 2 | |
|
|
Resistor 220 ohm |
x 2 |
Tools, APP Software Used etc.
|
Soldering Iron Kit |
|
|
arduino IDEArduino
|
Description
ESP32 Analog style VU meter with GC9A01 Round Dispalys + Peak Meters
A typical VU meter measures audio signals and displays them with a visual indicator. In the classic VU meter design is used a moving needle (actually a sensitive galvanometer) that points to a scale on a calibrated range.
The needle moves left or right depending on the strength of the audio signal. I recently acquired these small round TFT displays with a GC9A01 chip. Its basic purpose is for making smart watches, but in fact their shape is ideally suited for making a retro-look VU meter. My attention was drawn to a project on thesolaruniverse blog, which describes in detail how to create meters gauges and dials on this display with arduino nano.
For the needs of this project I made some modifications to the code but basically kept the beautiful retro design and colors. Now, instead of random values, the instrument shows the real values of the voltage applied to the input pin of the microcontroller. For a more homogeneous movement of the needle, I now use a more powerful ESP32 microcontroller.
This project is sponsored by PCBWay. This year, PCBWay is organizing the 11th badge design contest from March 3rd to April 31st. Follow the design requirements and Submit your designs in one of the given ways, and become the winner of one of the valuable prizes in cash and cupons. This contest is more than a competition—it’s a celebration of 11 years of innovation and a chance to dream about the boundless possibilities ahead with PCBWay.
Nowadays the price of ESP32 is very low, so for better separation of the channels I decided to use a separate microcontroller for each channel. In this project I also added a peak meter that signals the moment of exceeding the permitted level of the signal with an LED.
The device is very simple to make and consists of several components:
- ESP32 microcontroller - two pieces
- Two round displays with GC9A01 and 240x240 resolution
- envelope followers made with two small signal diodes and two capacitors
- and two leds with current limiting resistors
In particular, in this case I use the simplest passive envelope follower consisting of a diode and a capacitor, because the whole device is mainly intended as a demo device for testing, and based on this idea, a precise, fully functional audio VU meter can be made later with certain software and hardware modifications.
And now let's see how this VU meter works in real conditions.
Let me mention that a stereo potentiometer can be placed on the input in order to regulate the signal level, but for the sake of simplification I do it with the Windows mixer software.
And finally a short conclusion: This small, simple and interesting arduino project can be made in a few hours, and has a beautiful retro look, so you can use it as an additional part of any audio device, or as a stand-alone unit. With minimal code modification it can be used on many other devices (eg radio receiver) where signal strength measurement is required. The Vu meter is built in a suitable plastic box made of PVC material and lined with self-adhesive colored wallpaper.
Code
code L
C/C++
// GCA901_Nano_voltage_meter
//
// grid voltage variation monitor (230V - 250V AC)
// rolling averaged voltage (of 10 readings) is sent to display
// NOTE: here voltage generated with random function
//
// microcontroller: Arduino Nano
// display 240*240 circular SPI 3.3V TFT with GC9A01 controller
//
// note: random function drives fluctuations of the parameter named 'volt'
// CG9A01 Arduino Nano
// RST -------- NC
// CST -------- 10
// DC --------- 9
// SDA -------- 11 - green wire
// SCL -------- 13 - yellow wire
//
// Floris Wouterlood
// September 1, 2023
// public domain
// made for a 240*240 pixel circular display
// all x-y-coordinates relative to center = x = 120 and y = 120
#include "SPI.h"
#include "Adafruit_GFX.h"
#include "Adafruit_GC9A01A.h"
#define TFT_DC 2
#define TFT_CS 15
Adafruit_GC9A01A tft (TFT_CS, TFT_DC);
#define BLACK 0x0000 // some extra colors
#define BLUE 0x001F
#define RED 0xF800
#define GREEN 0x07E0
#define CYAN 0x07FF
#define MAGENTA 0xF81F
#define YELLOW 0xFFE0
#define WHITE 0xFFFF
#define ORANGE 0xFBE0
#define GREY 0x84B5
#define BORDEAUX 0xA000
#define AFRICA 0xAB21 // 0xce5f //0xAB21 // current dial color
const int vlez = 34;
#define DEG2RAD 0.0174532925
//int vlez;
int sig = 0;
int multiplier;
int frametime = 100;
int x_pos;
int y_pos;
int center_x = 120; // center x of dial on 240*240 TFT display
int center_y = 120; // center y of dial on 240*240 TFT display
float pivot_x, pivot_y,pivot_x_old, pivot_y_old;
float p1_x,p1_y,p2_x,p2_y,p3_x, p3_y, p4_x, p4_y, p5_x, p5_y;
float p1_x_old,p1_y_old, p2_x_old, p2_y_old, p3_x_old, p3_y_old;
float p4_x_old, p4_y_old, p5_x_old, p5_y_old;
float angleOffset = 3.14;
float arc_x;
float arc_y;
int radius = 120; // center y of circular scale
float angle_circle = 0;
float needleAngle = 0;
int iteration = 0;
int j;
float volt = 220;
int needle_multiplier = 1;
float needle_setter;
float currentNeedleValue = 230; // Start with a base voltage or level
float needleSpeed = 10; // Speed at which the needle returns to the left
// to start with
void setup() {
//randomSeed (analogRead(0));
pinMode(12, OUTPUT);
pinMode(vlez, INPUT);
tft.begin();
Serial.begin (9600);
Serial.println ("");
Serial.println ("");
tft.setRotation (0);
tft.fillScreen (BLACK);
tft.drawCircle (center_x, center_y,120, BLACK);
pivot_x = center_x;
pivot_y = center_y+50;
p1_x_old = center_x; p1_y_old = center_y+50;
p2_x_old = center_x; p2_y_old = center_y+50;
p3_x_old = center_x; p3_y_old = center_y+50;
p4_x_old = center_x; p4_y_old = center_y+50;
p5_x_old = center_x; p5_y_old = center_y+30;
create_dial ();
needle_setter = volt;
needleAngle = (((needle_setter)*DEG2RAD*1.8)-3.14);
needle();
draw_pivot ();
}
void loop (){
// Map the analog input (voltage) to the needle range
float targetNeedleValue = map(analogRead(vlez), 0, 400, 230, 270);
Serial.println(targetNeedleValue);
sig = analogRead(vlez);
if (sig > 280) {digitalWrite(12, HIGH);} else {digitalWrite(12, LOW);}
// If the target value is greater than the current needle position, move quickly
if (targetNeedleValue > currentNeedleValue) {
currentNeedleValue = targetNeedleValue;
}
// If the target value is lower, move more slowly to simulate damping
else if (targetNeedleValue < currentNeedleValue) {
currentNeedleValue -= needleSpeed; // Decrease the value gradually
if (currentNeedleValue < targetNeedleValue) {
currentNeedleValue = targetNeedleValue; // Ensure we don't overshoot
}
}
// Update the needle position
needle_setter = currentNeedleValue;
needle();
draw_pivot();
delay(frametime); // Control the update rate
}
void needle (){ // dynamic needle management
tft.drawLine (pivot_x, pivot_y, p1_x_old, p1_y_old, AFRICA); // remove old needle
tft.fillTriangle (p1_x_old, p1_y_old, p2_x_old, p2_y_old, p3_x_old, p3_y_old, AFRICA); // remove old arrow head
tft.fillTriangle (pivot_x, pivot_y, p4_x_old, p4_y_old, p5_x_old, p5_y_old, AFRICA); // remove old arrow head
needleAngle = (((needle_setter)*0.01745331*1.8)-3.14);
p1_x = (pivot_x + ((radius)*cos(needleAngle))); // needle tip
p1_y = (pivot_y + ((radius)*sin(needleAngle)));
p2_x = (pivot_x + ((radius-15)*cos(needleAngle-0.05))); // needle triange left
p2_y = (pivot_y + ((radius-15)*sin(needleAngle-0.05)));
p3_x = (pivot_x + ((radius-15)*cos(needleAngle+0.05))); // needle triange right
p3_y = (pivot_y + ((radius-15)*sin(needleAngle+0.05)));
p4_x = (pivot_x + ((radius-90)*cos(angleOffset+(needleAngle-0.2)))); // needle triange left
p4_y = (pivot_y + ((radius-90)*sin(angleOffset+(needleAngle-0.2))));
p5_x = (pivot_x + ((radius-90)*cos(angleOffset+(needleAngle+0.2)))); // needle triange right
p5_y = (pivot_y + ((radius-90)*sin(angleOffset+(needleAngle+0.2))));
p1_x_old = p1_x; p1_y_old = p1_y; // remember previous needle position
p2_x_old = p2_x; p2_y_old = p2_y;
p3_x_old = p3_x; p3_y_old = p3_y;
p4_x_old = p4_x; p4_y_old = p4_y; // remember previous needle counterweight position
p5_x_old = p5_x; p5_y_old = p5_y;
tft.drawLine (pivot_x, pivot_y, p1_x, p1_y, BLACK); // create needle
tft.fillTriangle (p1_x, p1_y, p2_x, p2_y, p3_x, p3_y, BLACK); // create needle tip pointer
// tft.drawLine (center_x-80, center_y+70, center_x+80,center_y+70, BLACK); // repair floor
tft.fillTriangle (pivot_x, pivot_y, p4_x, p4_y, p5_x, p5_y, BLACK); // create needle counterweight
}
void create_dial (){
tft.fillCircle (center_x, center_y,120, AFRICA); // general dial field
tft.drawCircle (center_x, center_y,118,GREY);
tft.drawCircle (center_x, center_y,117,BLACK);
tft.drawCircle (center_x, center_y,116,BLACK);
tft.drawCircle (center_x, center_y,115,GREY);
for (j= 30; j<60 ; j+=5)
{
needleAngle = ((j*DEG2RAD*1.8)-3.14);
arc_x = (pivot_x + ((radius+15)*cos(needleAngle))); // needle tip
arc_y = (pivot_y + ((radius+15)*sin(needleAngle)));
tft.drawPixel (arc_x,arc_y, BLACK);
tft.fillCircle (arc_x,arc_y,2, BLACK);
}
for (j= 60; j<75 ; j+=5)
{
needleAngle = ((j*DEG2RAD*1.8)-3.14);
arc_x = (pivot_x + ((radius+15)*cos(needleAngle))); // needle tip
arc_y = (pivot_y + ((radius+15)*sin(needleAngle)));
tft.drawPixel (arc_x,arc_y, RED);
tft.fillCircle (arc_x,arc_y,2, RED);
}
tft.setTextColor (BLACK,AFRICA);
tft.setTextSize (4);
tft.setCursor (center_x+55, center_y+40);
tft.print ("L");
tft.setTextSize (4);
tft.setCursor (center_x-70, center_y+40);
tft.print ("VU");
// tft.drawLine (center_x-80, center_y+70, center_x+80,center_y+70, WHITE); // create floor
}
void draw_pivot (){
tft.fillCircle (pivot_x, pivot_y,8,RED);
tft.drawCircle (pivot_x, pivot_y,8,BLACK);
tft.drawCircle (pivot_x, pivot_y,3,BLACK);
}
Code R
C/C++
// GCA901_Nano_voltage_meter
//
// grid voltage variation monitor (230V - 250V AC)
// rolling averaged voltage (of 10 readings) is sent to display
// NOTE: here voltage generated with random function
//
// microcontroller: Arduino Nano
// display 240*240 circular SPI 3.3V TFT with GC9A01 controller
//
// note: random function drives fluctuations of the parameter named 'volt'
// CG9A01 Arduino Nano
// RST -------- NC
// CST -------- 10
// DC --------- 9
// SDA -------- 11 - green wire
// SCL -------- 13 - yellow wire
//
// Floris Wouterlood
// September 1, 2023
// public domain
// made for a 240*240 pixel circular display
// all x-y-coordinates relative to center = x = 120 and y = 120
#include "SPI.h"
#include "Adafruit_GFX.h"
#include "Adafruit_GC9A01A.h"
#define TFT_DC 2
#define TFT_CS 15
Adafruit_GC9A01A tft (TFT_CS, TFT_DC);
#define BLACK 0x0000 // some extra colors
#define BLUE 0x001F
#define RED 0xF800
#define GREEN 0x07E0
#define CYAN 0x07FF
#define MAGENTA 0xF81F
#define YELLOW 0xFFE0
#define WHITE 0xFFFF
#define ORANGE 0xFBE0
#define GREY 0x84B5
#define BORDEAUX 0xA000
#define AFRICA 0xAB21 // 0xce5f //0xAB21 // current dial color
const int vlez = 34;
#define DEG2RAD 0.0174532925
//int vlez;
int sig = 0;
int multiplier;
int frametime = 100;
int x_pos;
int y_pos;
int center_x = 120; // center x of dial on 240*240 TFT display
int center_y = 120; // center y of dial on 240*240 TFT display
float pivot_x, pivot_y,pivot_x_old, pivot_y_old;
float p1_x,p1_y,p2_x,p2_y,p3_x, p3_y, p4_x, p4_y, p5_x, p5_y;
float p1_x_old,p1_y_old, p2_x_old, p2_y_old, p3_x_old, p3_y_old;
float p4_x_old, p4_y_old, p5_x_old, p5_y_old;
float angleOffset = 3.14;
float arc_x;
float arc_y;
int radius = 120; // center y of circular scale
float angle_circle = 0;
float needleAngle = 0;
int iteration = 0;
int j;
float volt = 220;
int needle_multiplier = 1;
float needle_setter;
float currentNeedleValue = 230; // Start with a base voltage or level
float needleSpeed = 10; // Speed at which the needle returns to the left
// to start with
void setup() {
//randomSeed (analogRead(0));
pinMode(12, OUTPUT);
pinMode(vlez, INPUT);
tft.begin();
Serial.begin (9600);
Serial.println ("");
Serial.println ("");
tft.setRotation (0);
tft.fillScreen (BLACK);
tft.drawCircle (center_x, center_y,120, BLACK);
pivot_x = center_x;
pivot_y = center_y+50;
p1_x_old = center_x; p1_y_old = center_y+50;
p2_x_old = center_x; p2_y_old = center_y+50;
p3_x_old = center_x; p3_y_old = center_y+50;
p4_x_old = center_x; p4_y_old = center_y+50;
p5_x_old = center_x; p5_y_old = center_y+30;
create_dial ();
needle_setter = volt;
needleAngle = (((needle_setter)*DEG2RAD*1.8)-3.14);
needle();
draw_pivot ();
}
void loop (){
// Map the analog input (voltage) to the needle range
float targetNeedleValue = map(analogRead(vlez), 0, 400, 230, 270);
Serial.println(targetNeedleValue);
sig = analogRead(vlez);
if (sig > 280) {digitalWrite(12, HIGH);} else {digitalWrite(12, LOW);}
// If the target value is greater than the current needle position, move quickly
if (targetNeedleValue > currentNeedleValue) {
currentNeedleValue = targetNeedleValue;
}
// If the target value is lower, move more slowly to simulate damping
else if (targetNeedleValue < currentNeedleValue) {
currentNeedleValue -= needleSpeed; // Decrease the value gradually
if (currentNeedleValue < targetNeedleValue) {
currentNeedleValue = targetNeedleValue; // Ensure we don't overshoot
}
}
// Update the needle position
needle_setter = currentNeedleValue;
needle();
draw_pivot();
delay(frametime); // Control the update rate
}
void needle (){ // dynamic needle management
tft.drawLine (pivot_x, pivot_y, p1_x_old, p1_y_old, AFRICA); // remove old needle
tft.fillTriangle (p1_x_old, p1_y_old, p2_x_old, p2_y_old, p3_x_old, p3_y_old, AFRICA); // remove old arrow head
tft.fillTriangle (pivot_x, pivot_y, p4_x_old, p4_y_old, p5_x_old, p5_y_old, AFRICA); // remove old arrow head
needleAngle = (((needle_setter)*0.01745331*1.8)-3.14);
p1_x = (pivot_x + ((radius)*cos(needleAngle))); // needle tip
p1_y = (pivot_y + ((radius)*sin(needleAngle)));
p2_x = (pivot_x + ((radius-15)*cos(needleAngle-0.05))); // needle triange left
p2_y = (pivot_y + ((radius-15)*sin(needleAngle-0.05)));
p3_x = (pivot_x + ((radius-15)*cos(needleAngle+0.05))); // needle triange right
p3_y = (pivot_y + ((radius-15)*sin(needleAngle+0.05)));
p4_x = (pivot_x + ((radius-90)*cos(angleOffset+(needleAngle-0.2)))); // needle triange left
p4_y = (pivot_y + ((radius-90)*sin(angleOffset+(needleAngle-0.2))));
p5_x = (pivot_x + ((radius-90)*cos(angleOffset+(needleAngle+0.2)))); // needle triange right
p5_y = (pivot_y + ((radius-90)*sin(angleOffset+(needleAngle+0.2))));
p1_x_old = p1_x; p1_y_old = p1_y; // remember previous needle position
p2_x_old = p2_x; p2_y_old = p2_y;
p3_x_old = p3_x; p3_y_old = p3_y;
p4_x_old = p4_x; p4_y_old = p4_y; // remember previous needle counterweight position
p5_x_old = p5_x; p5_y_old = p5_y;
tft.drawLine (pivot_x, pivot_y, p1_x, p1_y, BLACK); // create needle
tft.fillTriangle (p1_x, p1_y, p2_x, p2_y, p3_x, p3_y, BLACK); // create needle tip pointer
// tft.drawLine (center_x-80, center_y+70, center_x+80,center_y+70, BLACK); // repair floor
tft.fillTriangle (pivot_x, pivot_y, p4_x, p4_y, p5_x, p5_y, BLACK); // create needle counterweight
}
void create_dial (){
tft.fillCircle (center_x, center_y,120, AFRICA); // general dial field
tft.drawCircle (center_x, center_y,118,GREY);
tft.drawCircle (center_x, center_y,117,BLACK);
tft.drawCircle (center_x, center_y,116,BLACK);
tft.drawCircle (center_x, center_y,115,GREY);
for (j= 30; j<60 ; j+=5)
{
needleAngle = ((j*DEG2RAD*1.8)-3.14);
arc_x = (pivot_x + ((radius+15)*cos(needleAngle))); // needle tip
arc_y = (pivot_y + ((radius+15)*sin(needleAngle)));
tft.drawPixel (arc_x,arc_y, BLACK);
tft.fillCircle (arc_x,arc_y,2, BLACK);
}
for (j= 60; j<75 ; j+=5)
{
needleAngle = ((j*DEG2RAD*1.8)-3.14);
arc_x = (pivot_x + ((radius+15)*cos(needleAngle))); // needle tip
arc_y = (pivot_y + ((radius+15)*sin(needleAngle)));
tft.drawPixel (arc_x,arc_y, RED);
tft.fillCircle (arc_x,arc_y,2, RED);
}
tft.setTextColor (BLACK,AFRICA);
tft.setTextSize (4);
tft.setCursor (center_x+40, center_y+40);
tft.print ("VU");
tft.setTextSize (4);
tft.setCursor (center_x-60, center_y+40);
tft.print ("R");
// tft.drawLine (center_x-80, center_y+70, center_x+80,center_y+70, WHITE); // create floor
}
void draw_pivot (){
tft.fillCircle (pivot_x, pivot_y,8,RED);
tft.drawCircle (pivot_x, pivot_y,8,BLACK);
tft.drawCircle (pivot_x, pivot_y,3,BLACK);
}
Schematic and Layout
Schematic
SchematicJPG.jpg
Mar 13,2025
421 views
ESP32 Analog style VU meter with GC9A01 Round Dispalys + Peak Meters
Simple to build ESP32 VU meter on Round Dispalys with Peak Meters.
421
2
0
Published: Mar 13,2025
Standard PCB
PCBWay Donate 10% cost To Author
Under the
Attribution-ShareAlike (CC BY-SA)
License.
- Comments(0)
- Likes(2)
Upload photo
You can only upload 5 files in total. Each file cannot exceed 2MB. Supports JPG, JPEG, GIF, PNG, BMP
0 / 10000
More by Mirko Pavleski
-
Arduino 3D Printed self Balancing Cube
Self-balancing devices are electronic devices that use sensors and motors to keep themselves balanc...
-
Build simple Retro Style VFO (Variable frequency oscillator) with Crowoanel 1.28 inch Round Display
Today I received a shipment with a Small round LCD display from Elecrow. The device is packed in tw...
-
Human vs Robot – Rock Paper Scissors with MyCobot 280 M5Stack
Today I received a package containing the few Elephant Robotics products. The shipment is well pack...
-
How to Build a Simple Audio Spectrum Analyzer with Adjustable Settings
An audio spectrum analyzer is an electronic device or software tool that measures and visually disp...
-
How to Make a Digital Clock on a Vintage B&W TV using Arduino
These days I accidentally came across this small retro Black and White TV with a built-in Radio, so ...
-
Build a $10 Function Generator with Frequency Meter for Your Lab
A function generator is a piece of electronic test equipment used to generate various types of elec...
-
From Unboxing to Coding - Radar Clock on Elecrow’s 2.1 HMI Display
Today I received a shipment with a large round LCD display from Elecrow. The device is packed in two...
-
Making a Retro Analog NTP Clock with Unihiker K10 - Arduino IDE Tutorial
Some time ago I presented you a way to use standard Arduino libraries on the Unihiker k10 developme...
-
Build a Cheap & Easy HF Preselector - Antenna Tuner
HF antenna preselector is an electronic device connected between an HF radio antenna, and a radio r...
-
DIY Static Charge Monitor - Electrostatic Field Detector (Arduino & TL071)
A Static Charge Monitor also known as a Static Field Meter or Electrostatic Voltmeter is a device u...
-
XHDATA D-219 Radio Short Review with complete disassembly
Some time ago I received an offer from XHDATA to be one of the first test users of their new radio m...
-
How to make Simplest ever Oscilloscope Clock
An oscilloscope clock is a unique and creative way to display the time using an oscilloscope, which...
-
DIY Digital Barograph with BME280 and ESP32 - 24 Hour Pressure Trends
A barograph is a self-recording barometer that continuously measures and records atmospheric pressu...
-
Build a Raspberry Pi Pico SDR Radio with Waterfall Display
Software-defined radio (SDR) is a radio communication system where components that have traditional...
-
DIY Magnet Polarity Detector - How to Identify Poles with a Hall Sensor from a PC Fan
Recently, while working on a project, I needed to determine the polarity of several permanent magne...
-
Light Meter Project - Making Dfrobot Unihiker K10 Work with Standard Arduino Libraries
The other day I received a shipment with a UNIHIKER K10 development board from DFRobot, which I rec...
-
DIY Simple Arduino Whack-a-Mole Game
A "Whack-a-Mole" game is a classic arcade-style game where moles pop up randomly from holes, and th...
-
Wireless Power Transmission, Long-Distance and High-Efficiency with Class-E Tesla Coil
Wireless energy transfer also known as wireless power transmission is a method of getting useful el...
You may also like
-
-
-
-
Tester for Touch Screen Digitizer without using microcontroller
240 2 2 -
Audio reactive glow LED wristband/bracelet with NFC / RFID-Tags
242 0 1 -
-
-
