Posted on Leave a comment

Light Activated MP3 player (Part 1/2)

Light Activated MP3 Player

Light activated MP3 player was incepted when I wanted to add something special to the present that I gave to my Mrs. So while I was learning about Arduino and have a play with the DFPlayer Mini, which is essentially an MP3 player.

Step 1. Prepare the MP3 Player

First thing to do is to connect the DF Player mini to Arduino using the following circuit.


The SD card will need to contain an MP3 file, let’s say the file is 001.mp3, this is located in the 006 folder of the SD card, i.e.: sd:\\006\001.mp3.

Once you connect the diagram above you can use the following code to test to ensure that the DF Player is playing the song you had saved. If you came from Instructables, step 4. you would want the following code to test your DF player.

// this example will play a random track from all on the sd card
// it expects the sd card to contain some mp3 files
#include <SoftwareSerial.h>
#include <DFMiniMp3.h>
// implement a notification class,
// its member methods will get called 
class Mp3Notify
  static void OnError(uint16_t errorCode)
    // see DfMp3_Error for code meaning
    Serial.print("Com Error ");
  static void OnPlayFinished(uint16_t track)
    Serial.print("Play finished for #");
  static void OnCardOnline(uint16_t code)
    Serial.println("Card online ");
  static void OnCardInserted(uint16_t code)
    Serial.println("Card inserted ");
  static void OnCardRemoved(uint16_t code)
    Serial.println("Card removed ");
// instance a DFMiniMp3 object, 
// defined with the above notification class and the hardware serial class
//DFMiniMp3<hardwareserial, mp3notify> mp3(Serial1);
// Some arduino boards only have one hardware serial port, so a software serial port is needed instead.
// comment out the above definition and uncomment these lines
SoftwareSerial secondarySerial(10, 11); // RX, TX
DFMiniMp3<SoftwareSerial, mp3notify> mp3(secondarySerial);
int Song=1;   // 001.mp3
void setup() {
  // show some properties and set the volume
  uint16_t volume = mp3.getVolume();
  Serial.print("volume ");
  uint16_t count = mp3.getTotalTrackCount();
  Serial.print("files ");
  uint16_t mode = mp3.getPlaybackMode();
  Serial.print("playback mode ");
  //mp3.playRandomTrackFromAll(); // random of all folders on sd
  mp3.playFolderTrack(6, Song); // play song on sd:\\006\001.mp3

void loop() 
  // calling mp3.loop() periodically allows for notifications 
  // to be handled without interrupts

If you are having trouble loading the “DFMiniMp3” library you can download it from the Instructables step 6, the library called “DFPlayer_Mini_MP3”.

To take it to the next level I added the LDR, which is essentially a resistor which are photosensitive. The resistance changes when there is a light shine through it, combination of the 2 makes up the Light activated MP3 Player. We will go through this in the next part.


Posted on Leave a comment

Password Protect PDF document using windows Powershell script

Password protect PDF document can be done using Windows Powershell script. I stumble across a powerful script which allow to password protect PDF document using the script. The requirement that I have is to password protect a list of batch PDF document with a specified password that are different between each document and then sending each password protected PDF document to different individual emails.

So after researching for a while I found the script that does the job, but then I come across another hurdle, how do I get the list of password and the list of pdf, so my solution is to put the list of pdf files along with the password in an excel document, and let the script open the excel find the first pdf document, then read the designated password next to it, and run the script to password protect the file and save the password protected file in a different location.

So hunting around for the powershell script to read excel proven to be fruitful, so I combine both of them into one script. Here are the step by step on what I had done and how to modify this to suit your need. This proven to speed up the manual work by a lot. Not to imagine the time and cost savings that comes along with it.

Step 1. Create the list with location of PDF document and the password that you want to protect the document with.

In picture below, we have the source of document in column B, and the target encrypted PDF file name will be located in the location specified in column C. The password for each document will be based on the information in column D. Save this Excel file in C:\temp\ location and lets call the file Book2.xlsx for this exercise.

Step 2. Open your favourite text editor and paste in the following code, you can also use the “Windows PowerShell ISE“:


function PSUsing {
 param (
 [System.IDisposable] $inputObject = $(throw "The parameter -inputObject is required."),
 [ScriptBlock] $scriptBlock = $(throw "The parameter -scriptBlock is required.")
 Try {
 Finally {
 if ($inputObject.psbase -eq $null) {
 } else {

$xlCellTypeLastCell = 11 

$excel=new-object -com excel.application

for ($i=1; $i -le $wb.sheets.count; $i++)
 $rangeAddress=$sh.Cells.Item($startRow+1,$col).Address() + ":" +$sh.Cells.Item($endRow+1,$col).Address()
 $sh.Range($rangeAddress).Value2 | foreach {
 $contract=$sh.Cells.Item($startRow + $j,$col).Value2
 $filesource = $sh.Cells.Item($startRow + $j,$col+1).Value2
 $filedest = $sh.Cells.Item($startRow + $j,$col+2).Value2
 $dob=$sh.Cells.Item($startRow + $j,$col+3).Value2
 New-Object PSObject -Property @{Contract=$contract;Dob=$dob}
 $file = New-Object System.IO.FileInfo $filesource
 $fileWithPassword = New-Object System.IO.FileInfo $filedest
 $password = $dob
 PSUsing ( $fileStreamIn = $file.OpenRead() ) { 
 PSUsing ( $fileStreamOut = New-Object System.IO.FileStream($fileWithPassword.FullName,[System.IO.FileMode]::Create,[System.IO.FileAccess]::Write,[System.IO.FileShare]::None) ) { 
 PSUsing ( $reader = New-Object iTextSharp.text.pdf.PdfReader $fileStreamIn ) {
 [iTextSharp.text.pdf.PdfEncryptor]::Encrypt($reader, $fileStreamOut, $true, $password, $password, [iTextSharp.text.pdf.PdfWriter]::ALLOW_PRINTING)


Step 3. Make sure you have the itextsharp.dll library located in the same location as the PowerShell Script.

In this example it should be located in C:\Temp\. You should have the folder structure that looks similar to the one below.

Step 4. Put the source PDF files as specified in the step 1. Execute the Powershell Script by clicking on the execute button if you are using Windows PowerShell ISE.

Step 5. If everything went well, you should be able to see the execution message as per the picture below.

Step 6. The destination folders specified in excel step 1. should contain all the password protected PDF, as shown below.

Now you can tested these Password Protected PDF files by opening it using the password that you had specified in Step 1.

Please leave me a comments if you like this post. Like it if this help you to save some time in automating some of the boring task.