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I took a look at your library, actually I downloaded this library and tried to learn from it before weeks, but it was little complicated to me and I thought I better get back to my code and try to fix my problem, and I succeeded and I was so happy with this accomplishment.

The part I'm looking for is the methodology of converting the sting into dot matrix data.

I'm not interested into learning from MD_Parola because it requires another huge library which is MD_MAX72 library.

Even MD_Parola is bigger, I know I have to go to the part which deals with the specific process of converting the string pointer into the set of bytes, but it was so difficult for me to follow, also I don't know which source file is dealing with this function.

If you can just tell me how to take a pointer to string input and convert that to a set of 8-bytes of ASCII set for 8x8 displays.
Nederlands / Re: Ledstrip ws2812b aansturen
Last post by nicoverduin - Today at 08:57 pm is dacht ik de site zelf
Hardware / Re: Regulador se quema al cone...
Last post by tauro0221 - Today at 08:57 pm
Lo que yo no veo muy claro es porque necesitas usar los 12 voltios en Vin  mas el USB. Yo entiendo lo de del USB para recibir la informacion  pero a la misma vez lo que no entiendo es el  uso de  los 12 voltios tambien.El uso del Vin es suplir energia cuando no se usa el USB. Que tipo de interface usas  para controlar los 3 servomotores.
Deutsch / Re: LED Strip Blinker sehr lan...
Last post by Thorsten4171 - Today at 08:56 pm
Da reicht mein Verständniss nicht aus . Kannst du mir das verdeutschen?
Deutsch / Re: Led mit einem Taster ein u...
Last post by agmue - Today at 08:56 pm
Code: [Select]
pinMode(taster_pin, INPUT_PULLUP);
Der Eingang möchte gegen GND geschaltet werden, da ein PullUp-Widerstand ihn auf HIGH hält, wenn er unbeschaltet ist.
Thanks guys!
The code from Steveiboy worked like a charm!
Now i need to move on Processing :(
But do you understand why?

It is not enough to say it's working, then go on to the next problem for someone else to solve.

Hardware / Re: Pilotare relay 24VAC da ar...
Last post by nonzod - Today at 08:54 pm
Ma infatti avevo il sospetto ma ho grossi problemi a comprendere il datasheet del PCF8574, per mia ignoranza.
Ma potrei metterci immezzo degli NPN? Che poi forse va bene anche lavorare in Sink.
Project Guidance / Re: OS Detection?
Last post by MrMark - Today at 08:53 pm
This might work: Send the keystrokes for
hold Windows key down and send R - this will open the Run dialog
send "cmd.exe" and Enter - this opens a DOS/command window
send "echo whatever" - Now listen on the Serial input for "whatever" to be received. If it doesn't arrive in a reasonable amount of time it's not Windows.
There might be a similar process which works on Chromebook in which case your code could try them both.

"ver" in the cmd.exe window returns the windows version.  e.g. "Microsoft Windows [Version 10.0.15063]" on this machine.

What isn't clear to me is how the Arduino/USB device is registering with the PC.  If it is an USB HID device (i.e. emulating a keyboard as suggested in the previous thread), then the response goes to the screen, not back to the USB.  If the Arduino behaves as a USB Serial device it could connect as a user terminal in Linux and drive an interactive terminal session, but if that's supported in Windows (I've never seen it done on other than Windows Server versions) then it probably requires specific configuration on the Windows machine.
I'm a beginner, so sorry for my stupid question beforehand:
I'm currently working on an alarm system, where I'd like each "user" to have their own password. So far I managed to write a code with a password and have an "nfc-user" or something like that. What I'd like to do now is to make this password only acceptable if the nfc code matches the users.

I'm kinda stuck right now, so I'd be happy if someone could help me out a bit. Thanks in advance!

Code: [Select]
#include <Password.h>
#include <Keypad.h>
#define SS_PIN 9
#define RST_PIN 8
#include <SPI.h>
#include <MFRC522.h> 
String newPasswordString;
char newPassword[6];
Password password = Password( "314159" );
byte maxPasswordLength = 6;
byte currentPasswordLength = 0;
const byte ROWS = 4;
const byte COLS = 4;
char keys[ROWS][COLS] = {
byte rowPins[ROWS] = {5, 4,3 ,2};
byte colPins[COLS] = {12, 11, 7, 6};
Keypad keypad = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS );
MFRC522 mfrc522(SS_PIN, RST_PIN);

void setup(){
   pinMode(A0, OUTPUT);
   pinMode(A1, OUTPUT);
   pinMode(A2, OUTPUT);
   pinMode(10, OUTPUT);  //buzzer
void loop(){
char key = keypad.getKey();
if (key != NO_KEY){
switch (key){
case 'A': break;
case 'B': break;
case 'C': break;
case '#': checkPassword(); break;
case '*': resetPassword(); break;
default: processNumberKey(key);
   if ( ! mfrc522.PICC_IsNewCardPresent())

if ( ! mfrc522.PICC_ReadCardSerial())

long code=0;
for (byte i = 0; i < mfrc522.uid.size; i++)
code =((code+mfrc522.uid.uidByte[i])*10);

if (code==1879870)
  Serial.print("Welcome back, Lu!");
  Serial.print("Please enter your password:");
   analogWrite(A1, 150);
   tone(10, 1000, 500);
   analogWrite(A1, 0);
 else if (code != 1879870)
   analogWrite(A0, 150);
   tone(10, 1000, 500);
   analogWrite(A0, 0);

void processNumberKey(char key) {
if (currentPasswordLength == maxPasswordLength) {

void checkPassword() {
if (password.evaluate()){
      Serial.println(" OK.");
   } else {
      Serial.println(" Wrong password!");

void resetPassword() {
   currentPasswordLength = 0;
Deutsch / Re: LED Strip Blinker sehr lan...
Last post by agmue - Today at 08:53 pm
Gut dass der Compiler noch viel schlauer ist ...
[Klugscheisser an]
Der Compiler ist doof, die Leute, die ihn programmiert haben, sind schlau!
[Klugscheisser aus]
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