Category: Embedded software

The ESP8226 is a very cheap Wi-Fi microcontroller with a complete TCP/IP stack and a 32 bit microcontroller and is made by the Chinese manufacturer Espressif Systems. The chip came to attention in 2014 by a small board (ESP-01) as a cheap Wi-Fi module that could be controlled via a serial interface and through a form of Hayes commands. Soon the chip came to the attention of hackers, mainly due to its low cost, to find other uses. For the low amount of money, the specifications are impressive: a 32-bit RISC CPU (Tensilica Xtensa LX106) with an 80 MHz clock frequency, 64 Kb instruction RAM, 96 KB data RAM, external QSPI flash (512 Kb to 4 Mb), built-in IEEE 802.11 Wi-Fi stack, WEP and WPA/WPA2 authentication, 16 GPIO pins, SPI, I2C, UART and a 10-bit ADC. There are some nice cheap DIY boards for sale with this microcontroller and this page contains information about these boards, documentation, links and specifications, and development tooling. Also a full working sourcecode of a WIFI led controller. Sincerely, Hein Pragt

Wemos D1 mini

A relatively small manufacturer by the name of Wemos brings out nice new developments with the ESP-8266 family on Arduino type shields. One of these fun boards to experiment with yourself is the Wemos D1 mini, a small board equipped with a full Wi-Fi and network stack, a nice number of I/O ports, power supply, a USB connection, serial communication, bootloader, Flash memory and a 32 bit processor with an 80 MHz clock frequency. As in all very nice specifications for a board that costs less than 10 dollar. When you are already used to the standard Arduino IDE and programming environment, you can also use this for the Wemos D1. The correct boards have to be installed in the board manager of the IDE, but then it works almost immediately. There are already many libraries specifically for the ESP-8266 family available for the Wemos D1 mini but I find that many of the standard libraries written for the Arduino also work fine on the Wemos D1 mini. Because I2C and SPI also work standard, many of the boards and shields that are made for the Arduino can also be connected, please note that everything must work on 3v3, but this can also be solved with a level adjustment board or a resistance network. But a standard LCD display or a relay board can easily be connected. Sometimes a few I/O pins have to change definitions and often it works fine. But with 4 Mb of code space and 35 Kb of ram and a 32 bit processor at 80 MHz which is a huge improvement over the 16 MHz 8 bit Arduino processor with 1 to 2 Kb sram. The possibilities of the Wemos D1 mini are therefore very extensive, partly due to the built-in Wi-Fi that you can use ready-to-use.

Link: PDF with instructions for the Wemos D1 on the Arduin IDE.

Wemos OLED display

The first display I used is the WeMos D1 mini OLED shield 64×48 of 0.66 inch with an I2C interface. The shield has many more pins because it can also be controlled differently but of course we like to use I2C because it only uses two I/O lines. At 0.66inch it is quite a small display but is very easy to read as it has a high contrast. It uses the SSD1306 as the interface chip and uses the I2C address 0x3C or 0x3D which can be selected by a solder bridge on the back of the PCB. Very small, so I don’t dare and leave them at the default value. The device was delivered with separate header pins and since you only have 4 connections If you need it, you can also solder the wires directly to the PCB.

Code and example

Download: HERE my library for the Wemos D1 OLED display and install it via the IDE in your Arduino environment. Restart the IDE and look at the examples and see it says “oledtest64.ino”. The library works for the combination Wemos D1 and the Wemos OLED display. I also use this library myself and develop it further. With these basic functions you can create extensions in your own code.

I like libraries that only offer basic functions because I usually want to make things in my own way, which are just not in the library or just different which means I am compiling a large amount of code from a library that grows my code and is of no use to me. I wish good luck with this code.

The code of this libray is compact and contains only a few basic functions:

  public:
    Ssd1306(uint8_t i2caddr,uint8_t width,uint8_t height,uint8_t orientation);
    void begin(void); 
    void oledSetPixel(int16_t x, int16_t y, uint16_t color);
    void oledDrawLine(int16_t x0, int16_t y0, int16_t x1, int16_t y1, uint16_t color);
    void oledDrawRect(int16_t x, int16_t y, int16_t w, int16_t h, uint16_t color);
    void oledFillRect(int16_t x, int16_t y, int16_t w, int16_t h, uint16_t color);
    void oledDrawCircle(int16_t x0, int16_t y0, int16_t r,uint16_t color);
    void oledDrawChar(int16_t x, int16_t y, unsigned char c, uint16_t color);
    void oledPrintLine(int16_t x, int16_t y, unsigned char *c, uint16_t color);
    void oledInvert(void); 
    void oledNormal(void);
    void oledCopyDisplayBuffer(void);
    void oledClearDisplayBuffer(uint8_t value);

The displays can actually show only a little text, with a font of 5×7 this is the division on the screen and a resolution of 64 x 48 pixels, this gives ten columns and 5 rows, so you can effectively lose 50 characters on the screen.

Sourcecode Wi-Fi led control

This piece of sample code clearly shows the tremendous power of the Wemos D1 mini. The example uses my OLED library and otherwise only use standard supplied / built-in parts. Through this piece of code you can use your mobile phone via the web browser to find an output pin of the Wemos D1 mini module (read: connected relay) on and off. In this example I control the built-in LED. Since the more complete Wi-Fi stack and network stack are in the module as far as we don’t write our own code for this. First you make on your phone to a mobile hotspot and gives it a name and a password, you enter this name and password at const char* ssid and const char* password after which you can compile the code and upload it in the Wemos module. After turning on of the module, it will try to contact your mobile hotspot and then display its IP address on the screen. You then only need to enter this address in the address bar of the browser on your mobile phone and the Wemos module will now behave like an HTTP server and send you a page with the status of the led. Then you can click on a click on the links or switch the LED on the Wemos module on and off by means of a URL parameter. This is just a small example that can be food for many ideas, but I leave that to your imagination. kind regards, Hein Pragt.

// -----------------------------------------------
// Example code WI-FI led control
// -----------------------------------------------
#include 
#include 
#include 

const char* ssid = "HotspotVanUwTelefoon";
const char* password = "WachtwoordHotspotTelefoon";

int ledPin = BUILTIN_LED;
WiFiServer server(80);

Ssd1306 ssd1306(0x3C,64,48,0);

void setup() 
{
String ip;
char buffer[20];

  Serial.begin(9600);
  delay(10);  

  ssd1306.begin(); 
  // Clear the buffer.
  ssd1306.oledClearDisplayBuffer(0);
  ssd1306.oledCopyDisplayBuffer();

  pinMode(ledPin, OUTPUT);
  digitalWrite(ledPin, HIGH);

  // Connect to WiFi network
  ssd1306.oledPrintLine(0,0,"Connecting",1);
  Serial.print("Connecting to ");
  Serial.println(ssid);
  ssd1306.oledPrintLine(0,10,(char *)ssid,1); 
  ssd1306.oledCopyDisplayBuffer();

  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  ssd1306.oledClearDisplayBuffer(0);
  Serial.println("WiFi connected");
  ssd1306.oledPrintLine(0,0,"Connected ",1);
  ssd1306.oledCopyDisplayBuffer();

  // Start the server
  server.begin();
  Serial.println("Server started");

  // Print the IP address
  Serial.print("Use this URL : ");
  ssd1306.oledPrintLine(0,10,"MY IP:",1);
  Serial.print("http://");
  Serial.print(WiFi.localIP());
  ip = WiFi.localIP().toString();
  ip.toCharArray(buffer, 20);
  ssd1306.oledPrintLine(0,20,buffer,1);
  Serial.println("/");
  ssd1306.oledCopyDisplayBuffer();
}

void loop() {
  // Check if a client has connected
  WiFiClient client = server.available();
  if (!client) {
    return;
  }

  // Wait until the client sends some data
  Serial.println("new client");
  while(!client.available()){
    delay(1);
  }

  // Read the first line of the request
  String request = client.readStringUntil('\r');
  Serial.println(request);
  client.flush();

  // Match the request

  int value = HIGH;
  if (request.indexOf("/LED=ON") != -1) {
    digitalWrite(ledPin, LOW);
    value = LOW;
  } 
  if (request.indexOf("/LED=OFF") != -1){
    digitalWrite(ledPin, HIGH);
    value = HIGH;
  }



  // Return the response
  client.println("HTTP/1.1 200 OK");
  client.println("Content-Type: text/html");
  client.println(""); //  do not forget this one
  client.println("");
  client.println("");

  client.print("Led pin is now: ");

  if(value == LOW) {
    client.print("On");  
  } else {
    client.print("Off");
  }
  client.println("

");
  client.println("Click here turn the LED on pin 5 ON
");
  client.println("Click here turn the LED on pin 5 OFF
");
  client.println("");

  delay(1);
  Serial.println("Client disconnected");
  Serial.println("");

}

ESP8226 download and links

Here are some external links to pages and documents that will be helpful and helpful when getting started with the ESP8226.

• Download the Arduino IDE
• The ESP8266 Datasheet (Engels)
• Overview nice Wemos D1 projects.

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A nice feature of the Internet is online radio (also web radio, net radio, streaming radio, e-radio, IP radio, Internet radio). These are digital audio services transmitted via the Internet. Broadcasting on the Internet is usually referred to as webcasting since it is not transmitted broadly through wireless means. Internet radio involves streaming media, presenting listeners with a continuous stream of audio that typically cannot be paused or replayed, much like traditional broadcast media. The first Internet radio service was launched in 1993. Nowadays most popular radio stations also have an Internet radio stream and there are a lot of specialized radio stations, for instance I really like outlaw country music, and I have a few nice stations in the USA. Kind regards, Hein Pragt.

Building and ESP32 internet radio

So building an Internet radio is not that hard, we need a HTTP stack and a MP3 decoder. Both are available at a very good price, and we also add a simple display and a button to select a station. I have a 3D printer so I created a nice case as well. Lets start with the part list:

• A VS1053 MP3 codec board;
• ESP32 board (I used a WROOM version);
• OLED 64*128 display module I2C;
• Push button;
• 10 K resistor;

Oled Display Module 0.96 128×64 I2C

The display I used is a fairly standard OLED cheap display with white pixels, a resolution of 128 x 64 pixels and a control by means of I2C by the the SSD1306 driver IC. This shield also only needs two data lines and it consumes minimal current so that it can also be used in projects that need to be powered by a battery or battery. The size of this screen is slightly larger than the previous one and measures 26.0 x 15.0 mm. The module runs on 3v3 and can be connected to the outputs of the 3v3 output of the ESP32 and the I2C lines do not need voltage converters. The I2C address of this OLED shield is 0x3C by default. The screen is very clearly readable due to a very high contrast. The SSD1306 is a single-chip CMOS OLED/PLED driver with controller for displays with a maximom resolution of 128 x 64. The IC contains a display controller with display RAM and a built-in oscillator so that it can be used with minimal external components. It has a built-in 256 steps brightness control. It has a 6800/8000 series compatible Parallel Interface and a I2C interface.

VS1053 MP3 codec board

The VS1003 audio codec module is a complete MP3/WMA/MIDI audio decoder and ADPCM encoder that features a high quality stereo DAC (Digital to Analog Converter), a 16-bit adjustable ADC (Analog to Digital Converter) and a high quality stereo earphone driver (30 ohms). This module is ideal for adding audio decoding and encoding capabilities to embedded systems. It has a serial data and control interface (SPI) that makes it easy to connect to the ESP32 or any othe board that has an SPI interface. It also has a headphone and audio output interface and a microphone for recording but we cont be using this. It supports MP3 and WAV stream and has a single 5 V power supply that is On-board converted to 3.3 V and 2.5 V for the chips on the board and it uses about 800 mA. When we feed it with 32 bytes chunks of audio data, it will decode and output the audio trough the headphone jack. We can connect this to an amplifier to play it on a stereo set or PC speaker set.

ESP32 connections

ESP32 internet radio shematics

Connecting everything up is not that hard, although the pins on the ESP32 are very hard to read because the text is very small. Also check the pins of the ESP32 board you have, I have noticed some difference in different boards. The name of the pin is the clue you have to follow. The entire device is powered through the micro-usb port of the ESP32. Load the code in the Arduino IDE (you have to make sure it supports the ESO32 first) and you may have to download some additional libraries like the “ESP_VS1053_Library-master” and the “esp8266-oled-ssd1306-master” library. Find the place in the code where you have to put your WIFI network name and password and compile the code.

After uploading the software it will say a welcome phrase and then connect to the WIFI. It will remember the last station you selected and then start streaming the MP3 data to the MP3 codec and you will hear the internet radio station. I really like this little device and I have filled the array in the source code with a few radio stations, you can delete and add your own, as you like and personalize the device. Have fun.

The ESP32 sourcecode

Do not copy and paste, the download link is below the listing!

// ----------------------------------------------------------------
// ESP32 + VS1053  Internet radio
// Hein Pragt 2022
//
// VS1053 - connections 
// XRST = EN (D3)
// MISO = D19
// MOSI = D23
// SCLK = D18
// VCC = 5V / 3.3 V  and  Gnd = Gnd 
// ----------------------------------------------------------------

#include <VS1053.h> 
#include <Preferences.h> 
#include "StartMp3.h"
#include <WiFi.h>
#include <HTTPClient.h>
#include <esp_wifi.h>
#include "SSD1306.h"

char ssid[] = "your wifi ssid";
char pass[] = "your wifi password";

Preferences preferences;
SSD1306     display(0x3c, 21,22);
WiFiClient  client;

unsigned int counter,old_counter;
int change = 13;
bool pinflag = true;
int status = WL_IDLE_STATUS;
uint8_t mp3buffer[128]; 

struct _stationList {
  char sname[64];
  char host[128];
  char path[128];
  int  port;
} stationList[] = {
{ "NPO Radio 1 " ,   "icecast.omroep.nl", "/radio1-bb-mp3", 80 },
{ "NPO Radio 2 " ,   "icecast.omroep.nl", "/radio2-bb-mp3", 80 },
{ "NPO 2 S & J " ,   "icecast.omroep.nl", "/radio6-bb-mp3", 80 },
{ "NPO 3FM     " ,   "icecast.omroep.nl", "/3fm-bb-mp3", 80 },
{ "NPO 3FM Alt " ,   "icecast.omroep.nl", "/3fm-alternative-mp3", 80 },
{ "NPO Radio 5 " ,   "icecast.omroep.nl", "/radio5-bb-mp3", 80 },
{ "538 Radio   " ,   "20073.live.streamtheworld.com", "/RADIO538.mp3", 80 },
{ "QMusic      " ,   "icecast-qmusicnl-cdp.triple-it.nl", "/Qmusic_nl_live.mp3", 80 },
{ "Radio 10    " ,   "25533.live.streamtheworld.com", "/RADIO10.mp3", 80 },
{ "Radio 10 70 " ,   "22343.live.streamtheworld.com", "/TLPSTR18.mp3", 80 },
{ "Radio 10 80 " ,   "25233.live.streamtheworld.com", "/TLPSTR20.mp3", 80 },
{ "Radio 10 90 " ,   "25353.live.streamtheworld.com", "/TLPSTR22.mp3", 80 },
{ "Radio 10 Love" ,  "25293.live.streamtheworld.com", "/TLPSTR04.mp3", 80 },
{ "Veronica    " ,   "22343.live.streamtheworld.com", "/VERONICA.mp3", 80 },
{ "Sky Radio   " ,   "25293.live.streamtheworld.com", "/SKYRADIO.mp3", 80 },
{ "Country Rocks" ,  "stream.dbmedia.se", "/crrMP3", 80 },
{ "Outlaw Country" , "ice10.securenetsystems.net", "/KIEV2", 80 },
{ "~" ,   "0", "0", 80 },
{ "~" ,   "0", "0", 80 },
{ "~" ,   "0", "0", 80 },
{ "~" ,   "0", "0", 80 },
{ "~" ,   "0", "0", 80 },
{ "~" ,   "0", "0", 80 },
{ "~" ,   "0", "0", 80 },
{ "~" ,   "0", "0", 80 },
{ "~" ,   "0", "0", 80 },
{ "~" ,   "0", "0", 80 },
{ "~" ,   "0", "0", 80 },
{ "~" ,   "0", "0", 80 },
{ "~" ,   "0", "0", 80 },
{ "~" ,   "0", "0", 80 },
{ "~" ,   "0", "0", 80 },
{ "~" ,   "0", "0", 80 },
{ "~" ,   "0", "0", 80 },
{ "~" ,   "0", "0", 80 },
{ "~" ,   "0", "0", 80 },
{ "~" ,   "0", "0", 80 },
{ "~" ,   "0", "0", 80 },
{ "~" ,   "0", "0", 80 },
{ "~" ,   "0", "0", 80 },
{ "~" ,   "0", "0", 80 },
{ "~" ,   "0", "0", 80 },
{ "~" ,   "0", "0", 80 },
{ "~" ,   "0", "0", 80 },
{ "~" ,   "0", "0", 80 },
{ "~" ,   "0", "0", 80 },
{ "~" ,   "0", "0", 80 },
{ "~" ,   "0", "0", 80 }
};


// Wiring of VS1053 board (SPI connected in a standard way)
#define VS1053_CS    32
#define VS1053_DCS   33
#define VS1053_DREQ  35 

#define VOLUME  100      // volume level 0-100

VS1053 player(VS1053_CS, VS1053_DCS, VS1053_DREQ);

// -----------------------------------------
// Setup and init
// -----------------------------------------

void setup ()
{
display.init();
display.invertDisplay();
display.setFont(ArialMT_Plain_16);
display.normalDisplay();
display.setColor(WHITE);
display.drawString(0,0,"  ESP32 Radio");
display.setFont(ArialMT_Plain_10);
  
   pinMode(change,INPUT_PULLUP);
   Serial.begin(115200);
   delay(500);
   SPI.begin();
   player.begin();   // initialize VS1053 player
   player.setVolume(VOLUME);
   
   WiFi.begin(ssid, pass);
   while (WiFi.status() != WL_CONNECTED) {
     delay(500);
     Serial.print(".");
   }
  Serial.println("WiFi connected");  
  Serial.print("IP address:");  
  Serial.println(WiFi.localIP());
  display.setColor(WHITE);
  preferences.begin("my-app", false);
  counter = preferences.getUInt("counter", 0);
  old_counter = counter;
  delay(100);
  player.playChunk(StartUp, sizeof(StartUp)); //VS1053 is wake up & running
  delay(1000);
  station_connect(counter); 
}


// -----------------------------------------
// Main loop
// -----------------------------------------

void loop()
{
  // Play stream
  if (client.available() > 0) {
     uint8_t bytesread = client.read(mp3buffer, 128);
     player.playChunk(mp3buffer, bytesread);
  }
  // Check key
  if (digitalRead(change) == 0 and pinflag == true) {
    pinflag = false;
    counter++;
    if (stationList[counter].sname[0] == '~') { // Empty field
      counter = 0;
    }
  } 
  if (old_counter != counter) {
    player.softReset(); 
    pinflag = true;
    station_connect(counter); 
    old_counter = counter;
  } 
}


// -----------------------------------------
// Connect to radiostation
// -----------------------------------------

void station_connect (int station_no) 
{
  if (client.connect(stationList[station_no].host,stationList[station_no].port) ) {
    Serial.println("Connected now");
  }
  client.setNoDelay(true);
  Serial.print(String("GET ") + stationList[station_no].path + " HTTP/1.1\r\n" + "Host: " + stationList[station_no].host + "\r\n" + "Connection: close\r\n\r\n");     
  client.print(String("GET ") + stationList[station_no].path + " HTTP/1.1\r\n" + "Host: " + stationList[station_no].host + "\r\n" + "Connection: close\r\n\r\n");     
  display.clear();
  display.setFont(ArialMT_Plain_16);
  display.drawString(0,0,"ESP32  Radio");
  display.drawString(0,21,"Station: " + String(station_no));
  String line4 = String(stationList[station_no].sname); 
  display.drawString(0,42,line4.substring(0,60));
  display.display();
  preferences.putUInt("counter",station_no); 
  Serial.printf("Set counter to new_value: %u\n", station_no);
}

Downloads

Download: Full sourcecode Zip file.

To compile the code you will need some libraries, i have used the next libraries:

• ESP_VS1053_Library-master
• esp8266-oled-ssd1306-master

This is my build

I also have a 3D printer and I design using Freecad so I made my own case for this internet radio.

Links

• Wikipedia Internet radio.
• List of Internet radio stations.

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On this page I will document and explain how to build a relatively cheap electric door lock based on an Arduino Nano and a RFID shield. I have a small garden with a bicycle shed that has a door to the common area behind our house. I have a lock on this door, but a lot of people have a key, my children, my neighbor and buying a new spare key takes long and is expensive. And then people lose their key, so I thought of a simple solution where I could make many keys and could authorize, but also unauthorize keys. I though of a solution using simple 125 Khz RFID keys and a cheap reader and an Arduino Nano processor. I ordered an electric lock online because it was hard to get here in a shop and rather expensive. I gave everyone who needs access to my garden (fi. to feed the animals) a small RFID key, and created a 3D printed reader next to the door and its working fine. On thsi page I will show you how I build it, because it’s all standard components, you could design your own version, if for instance you add a clock chip you could even give certain RFID keys only access at specific times. You can download all the files from this website, if hope this project will inspire you to create your own version. Regards, Hein Pragt

Step 1: So What Components Do You Need?

• An Arduino Nano board;
• EM4100 RDM-6300 RFID card reader 125 khz (or compatible);
• Some 125 Khz RFID badges;
• Led with 330 Ohm resistor;
• 2N7002 Mosfet;
• 10 K resistor;
• 1N4004 diode;
• 5 Volt relay;
• 7808 voltage regulator;
• 12V power supply at least 2A;
• Terminal connector for power;
• Terminal connector for lock wires;
• An electric lock (Fail-Secure);
• PCB board to mount the parts;
• Female header pins to mount the Arduino and RFID reader.

I usually mount the Arduino Nano and other boards with a female pin header so they can be easily replaced when broken or if they are failing. The lock needs 12V power and I wanted a single power supply, so in order to save the Arduino from becoming very hot, I put a 7808 power regulator chip between the 12V power line and the Vin of the Arduino, I use a 5 Volt relay to switch the power to the electric lock because this device will draw a lot of current. I have used a cheap 12v switching power supply, but you can use any power supply that’s 12 V and can deliver at least 2 or 3 Amp current. For the RFID badges I use the read-only ones, they have a fixed number inside and are cheaper than the R/W badges,

Step 2: The Whole Diagram

This is the diagram of the lock system.I build it on a PCB board using several colors of wire, the diagram is not that complex. I use a 7808 power converter to lower the 12 voltage for the Arduino to 8 volt, I don’t use the capacitors on both sides as the input power is stable and the Arduino does not use too much power. But you could put two 1 uf capacitors on bothe sides of the 7808. I use the +5v output from the Arduino to power the rest of the circuit. I use a mosfet (the old common 2n7002) to drive a relay to switch the 12 v power to the lock. As the lock can draw a lot of current its save to use a relay. I took a little plastic case to hold the electronics and I 3D printed a little case on the outside to hold the antenna and the indicator led.

I also designed a holder for the lock to mount it next to the door. I also used a standard door lock on the door with a latch that will move inside when the door closes. I designed a knob to mount on the lock to be able to open the lock from the inside without a RFID badge. (The third file of the knob, the axis, should be printed with 100% infill to make it strong enough) I also created a 4mm spacer for the lock, so you can mount it right in front of the latch. The lock and latch should fit loosely otherwise the unlock won’t work. I used a 12 volt 3 A switching power supply for the 12 volt and I mounted it in the top of the bicycle shed in a dry space. I have used a 3 meter wire to connect the 12 volt to the lock system.

Step 5: The Software.

I wrote a very small Arduino program to read the RFID badges and display them on the serial interface so you can read the value inside the badge. Then you can add the hexadecimal number to the array at the top of the file (don’t forget to increment the number of cards below the array). When a valid card is detected the pin 12 of the Arduino controlling the relay pin will be activated for 5 seconds. You can adjust this time to your own needs. I use the software serial to read the badge so the other serial port is free for other use. There are a lot of pins left on the Arduino, you could add a I2C clock module and enable certain badges only at certain times. There is programming space left so add what you want. The basic version is working code and currently mounted in my own backyard.

Download

• Download zip file with the sourcecode
• Download zip file with STL files of the antenna unit
• Download zip file with STL files of the doorknob
• Download hier de Arduino IDE
• This is where I bought the electric lock for a good price

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