user37282: I am working with RFID-RC522 and Arduino UNO. I have check pin configurations again and again tried different libraries. It is not reading card and red led on RC522 is consistently on.

user37523: Here's a picture of the card reader I have. If yours looks identical, then this library should work: https://github.com/ljos/MFRC522

The auth_read_write.ino sketch worked for me. Before you install the library, I recommend removing any other MFRC522 libraries from your arduino/library folder.
The only thing I did differently was used a 74HC4050 running at 3.3V between the Arduino and card reader. Some people claim you can connect the reader directly to the Arduino. I didn't want to take a chance of burning out the card reader so I used the 74HC4050.
Here's how I connected it:
Component markings and connections

|-------------------------------------------|
|   SPI    |  UNO  | 74HC4050  | RFID-RC522 |
|----------|-------|-----------|------------|
| SDA (SS) |  10   |     7     |            |
| SDA (SS) |       |     6     |    SDA     |
| SCK      |  13   |     5     |            |
| SCK      |       |     4     |    SCK     |
| MOSI     |  11   |     3     |            |
| MOSI     |       |     2     |    MOSI    |
| MISO     |  12   |           |    MISO    |
| IRQ      |  N/C  |    N/C    |    N/C     |
| GND      |  GND  | 8,9,11,14 |    GND     |
| RST      |   5   |           |    RST     |
| 3.3V     |       |     1     |    3.3V    |
|-------------------------------------------|


37282: <p>I am working with RFID-RC522 and Arduino UNO. I have check pin configurations again and again tried different libraries. It is not reading card and red led on RC522 is consistently on.</p>
 37523: <p>Here's a picture of the card reader I have. If yours looks identical, then this library should work: <a href="https://github.com/ljos/MFRC522" rel="nofollow noreferrer">https://github.com/ljos/MFRC522</a></p>

<p><a href="https://i.stack.imgur.com/rB2FH.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/rB2FH.jpg" alt="enter image description here"></a></p>

<p>The auth_read_write.ino sketch worked for me. Before you install the library, I recommend removing any other MFRC522 libraries from your arduino/library folder.</p>

<p>The only thing I did differently was used a 74HC4050 running at 3.3V between the Arduino and card reader. Some people claim you can connect the reader directly to the Arduino. I didn't want to take a chance of burning out the card reader so I used the 74HC4050.</p>

<p>Here's how I connected it:</p>

<pre><code>Component markings and connections

|-------------------------------------------|
|   SPI    |  UNO  | 74HC4050  | RFID-RC522 |
|----------|-------|-----------|------------|
| SDA (SS) |  10   |     7     |            |
| SDA (SS) |       |     6     |    SDA     |
| SCK      |  13   |     5     |            |
| SCK      |       |     4     |    SCK     |
| MOSI     |  11   |     3     |            |
| MOSI     |       |     2     |    MOSI    |
| MISO     |  12   |           |    MISO    |
| IRQ      |  N/C  |    N/C    |    N/C     |
| GND      |  GND  | 8,9,11,14 |    GND     |
| RST      |   5   |           |    RST     |
| 3.3V     |       |     1     |    3.3V    |
|-------------------------------------------|
</code></pre>
