RFID Reader LED not turning red

joubin · 2011-04-14 19:28

Hi,

I am experimenting with the Parallax serial RFID reader/writer connected to an Arduino. I ran some simple programs I found on the net, but the LED on the reader doesn't ever turn red which would indicate that the reader is ready to scan tags.

So I thought I would simplify things and take the Arduino out of the circuit. According to the reader's documentation, I ought to be able to provide power and ground to the reader and tie ENABLE to GND, causing the reader to go into active mode. But even then, the LED stays green, indicating the reader is in idle mode.

Are there any other troubleshooting steps I can take? Do I have a malfunctioning reader?

ElectricAye · 2011-04-14 19:54

Welcome to the forums.

From page 4 of the RFID manual... wrote:

A visual indication of the state of the RFID Card Reader is given with the on-board LED. When the
module is successfully powered-up and is in an idle state, the LED will be GREEN. When the module is in
an active state searching for or communicating with a valid tag, the LED will be RED.

To me, the manual seems a little ambiguous on what the LED colors might mean. But is it possible that green actually means that it's ready to scan a tag, but it turns red when it is in the process of communicating with a tag? Have you tried to get it to communicate with a tag, yet?

PJAllen · 2011-04-14 20:09

Here's a link to a video featuring the Parallax RFID Reader
http://www.youtube.com/watch?v=FKHdhZuIov8

joubin · 2011-04-14 20:42

if you look at the video, it looks like its red, and once something is scanned, it turns green.
Is there a test code that I can run for this. Im using Arduino kit.

PJAllen · 2011-04-14 21:00

OK. RFID_D and Enable are necessary RFID pins, "status" is for the white LED that I placed.

RFID_D  PIN 0  ' input
Enable  PIN 1  ' output
status  PIN 2  ' output

Get_a_tag:
  LOW Enable      ' RFID Up !
  status = 0      ' ON = Ready
  SERIN RFID_D, T2400, [WAIT($0A), STR buf\10]
  HIGH Enable     ' going RFID low power
  status = 1

joubin · 2011-04-14 21:19

Im so sorry that I sound stupid. This is my first time doing this. the code that you have up there, what do i do with it. My worry is that I have a bad RFID. I have not yet seen a red light on it. Can someone give me a code that will just turn on my red let. Thats all I want. Some test to proof that the RFID part is ok

ElectricAye · 2011-04-14 21:38

joubin wrote: »

if you look at the video, it looks like its red, and once something is scanned, it turns green.
....

Yes, you're right. The video makes it obvious. My apologies for making useless comments. P J Allen dwells in Outer Darkness and I don't know what I'm talking about half the time.
You might send a private message to Microcontrolled and see if he has any suggestions. He's the only person I know off the top of my head who has worked with the RFIDs.
http://forums.parallax.com/member.php?54463-Microcontrolled

Don't give up. Somebody on this forum can give you a good, direct answer to your question.

Mike Green · 2011-04-14 21:55

You're getting various answers because you're using the RFID reader/writer and most people here are used to the RFID reader. They behave differently. The RFID reader has a red LED that goes on when the reader is enabled. See page 3 of the reader/writer documentation for an unambiguous description of what the red/green LED does. The documentation is quite complete in describing how to use the RFID reader/writer.

Note that the documentation says that the data (following the commands) is sent in hexadecimal. That's not strictly correct. The data is sent as raw 8-bit bytes. You write it in your program as hexadecimal or decimal, but the compiler translates that into 8-bit byte values.

joubin · 2011-04-14 22:14

Mike. Thats the best answer I've gotten. Im freaking out here. I was wondering if you can tell me where to go from here.
I have the ardurino kit http://www.amazon.com/Cana-Kit-Arduino-Starter/dp/B004G1AIJM/ref=sr_1_3?ie=UTF8&qid=1302844307&sr=8-3
this is the reader/write i bought. http://www.parallax.com/StoreSearchResults/tabid/768/List/0/SortField/4/ProductID/688/Default.aspx?txtSearch=rfid+write
and im using this tutorial http://www.gumbolabs.org/2009/10/17/parallax-rfid-reader-arduino/ and it talks about a write method.

It compiles using the ardurino and even passes it to the device. nothing happens after that.

Thanks so much

PJAllen · 2011-04-15 05:42

Well, I fell into the Title vs. Post Trap.
The Title's about "RFID Reader", but the Post's about "RFID R/W"
I helped another guy with what turned out to be a R/W, but it was in a BasicStamp context.
I don't do arduina so I don't have a magic arduina lib to turn you on to - it's not my bag.

Mike Green · 2011-04-15 06:37

The tutorial you referenced is for the RFID Reader. You have a completely different device. You need to thoroughly read the documentation for your RFID Reader/Writer (see link above). The Reader/Writer requires a serial port, one I/O pin where the Arduino transmits to the Reader/Writer and another I/O pin where the Arduino receives from the Reader/Writer. I can't help you with the programming, but there should be plenty of examples in the Arduino documentation/forums for the Arduino talking to a serial device.

Since the examples in the Reader/Writer documentation are in Parallax Basic, you might want to download the Stamp Manual so you can see what the examples mean.

Microcontrolled · 2011-04-15 11:56

I haven't worked with the read/write module, but I have worked a lot with the reader. According to the documentation there is a little more to it than just grounding the /ENABLE pin. After reading the documentation, it appears to activate the scanner, you have to send the ASCII string "!RW" (without the quotes) and than decimal 1, followed by decimal 32 at 9600 baud. Of course, for other commands, refer to the documentation.

RFID Reader LED not turning red

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