RFID RC255 not reading cards on my Arduino uno

Hello i recently bought this RFID RC255 sensor on amazon :

And tried to use it with this code :

#include <SPI.h>
#include <RFID.h>
RFID monModuleRFID(10,9);
int UID[5];
void setup()
{
Serial.begin(9600);
SPI.begin();
monModuleRFID.init();
}
void loop()
{
if (monModuleRFID.isCard()) {
if (monModuleRFID.readCardSerial()) {
Serial.print("L'UID est: ");
for(int i=0;i<=4;i++)
{
UID_=monModuleRFID.serNum*;_
_ Serial.print(UID,DEC);
Serial.print(".");
}
Serial.println("");
}
monModuleRFID.halt();
}
delay(1);
}[/color][/justify]
[/quote]
but nothing is display in the serial monitor. leds of the arduino and the rc255 are On. ( see below )
I tried the 3.3V and 5V voltage and it didn't work
I tried this new code with new libraries and I got this issue :
"Warning : Communication failure, is the MFTC522 properly connected ?"
Can someone help me ?
Thank you :slight_smile:



_


*

Did you solder that??? :stuck_out_tongue_closed_eyes: :stuck_out_tongue_closed_eyes:

I think you should first check you soldering points to make sure. I would take out all the points and solder them new. They look cold to me.

I'm learning soldering and i got a big iron tip.. i have already soldered them twice. Is there a method to check pins one by one ?
I thought the pins were well soldered since leds were on!!
But yes i think it's certainly a soldering issue...

nestaflex:
I’m learning soldering and i got a big iron tip… i have already soldered them twice. Is there a method to check pins one by one ?
I thought the pins were well soldered since leds were on!!
But yes i think it’s certainly a soldering issue…

I would advise you to buy a used Weller (You could probably find one for around 80€). A good quality soldering iron makes a big difference. I guarantee you that you will learn how to solder very quickly and you will have a lot of fun doing it.
Your LED’s could be on because VCC and GND is fine. However, your other pins could have a bad connection.

You can try with a multimeter to check the pins (Check resistance between the small points and the other side of the pin). But I cannot stress enough the importance of a good soldering point.