I got an Parallax Read/Write Module http://www.parallax.com/StoreSearchResults/tabid/768/txtSearch/rfid/List/0/SortField/4/ProductID/688/Default.aspx
How to connect it to our board. ( ex. MEGA)
I connected to the serial , but I dont know how to start , what to send to the module , to start readin tags.
Give me an example of code to read tags! Thanks..
It is a well documented and most simple serial protocol
' =========================================================================
'
' File...... rfid_rw_test.bs2
' Purpose... System-level test code for the Parallax RFID Read/Write Module
' Author.... Joe Grand, Grand Idea Studio, Inc. [www.grandideastudio.com]
' E-mail.... support@parallax.com
' Updated... 15 Dec 2009
'
' {$STAMP BS2}
' {$PBASIC 2.5}
'
' =========================================================================
' -----[ Program Description ]---------------------------------------------
'
' This program performs a system-level test of the Parallax RFID Read/
' Write Module by:
'
' 1) Reading tag's unique ID
' 2) Writing and verifying a block of data to the tag
' -----[ I/O Definitions ]-------------------------------------------------
RFID_TX PIN 0 ' Connects to RFID R/W Module SIN
RFID_RX PIN 1 ' Connects to RFID R/W Module SOUT
' -----[ Constants ]-------------------------------------------------------
#SELECT $STAMP
#CASE BS2, BS2E, BS2PE
T9600 CON 84
#CASE BS2SX, BS2P
T9600 CON 240
#ENDSELECT
Baud CON T9600
' RFID R/W Module Commands
' Number of bytes returned in ()
RFID_Read CON $01 ' Read data from specified address, valid locations 1 to 33 (5)
RFID_Write CON $02 ' Write data to specified address, valid locations 3 to 31 (1)
RFID_Login CON $03 ' Login to tag with password (1)
RFID_SetPass CON $04 ' Change tag's password from old to new (1)
RFID_Protect CON $05 ' Enable/disable password protection (1)
RFID_Reset CON $06 ' Reset tag (1)
RFID_ReadLegacy CON $0F ' Read unique ID from EM4102 read-only tag (for backwards compatibility with Parallax RFID Card Reader, #28140 and #28340) (12)
' Memory map/address locations for EM4x50 tag
' Each address holds/returns a 32-bit (4 byte) value
ADDR_Password CON 0 ' Password (not readable)
ADDR_Protect CON 1 ' Protection Word
ADDR_Control CON 2 ' Control Word
' ADDR 3-31 are User EEPROM area
ADDR_Serial CON 32 ' Device Serial Number
ADDR_DeviceID CON 33 ' Device Identification
' Status/error return codes
ERR_OK CON $01 ' No errors
ERR_LIW CON $02 ' Did not find a listen window
ERR_NAK CON $03 ' Received a NAK, could be invalid command
ERR_NAK_OLDPW CON $04 ' Received a NAK sending old password (RFID_SetPass), could be incorrect password
ERR_NAK_NEWPW CON $05 ' Received a NAK sending new password (RFID_SetPass)
ERR_LIW_NEWPW CON $06 ' Did not find a listen window after sending old password (RFID_SetPass)
ERR_PARITY CON $07 ' Parity error when reading data
' -----[ Variables ]-------------------------------------------------------
buf VAR BYTE(12) ' data buffer
idx VAR BYTE ' index
idy VAR BYTE
' -----[ EEPROM Data ]-----------------------------------------------------
' -----[ Initialization ]--------------------------------------------------
Initialize:
PAUSE 250 ' let DEBUG open
DEBUG CLS ' clear the screen
DEBUG "Parallax RFID Read/Write Module Test Application", CR,
"------------------------------------------------", CR, CR
' -----[ Program Code ]----------------------------------------------------
Main:
DEBUG "Reading tag's unique serial number..."
Read_Tag:
SEROUT RFID_TX, Baud, ["!RW", RFID_Read, ADDR_Serial] ' Read tag's serial number
SERIN RFID_RX, Baud, [STR buf\5] ' Get status byte and data bytes
IF buf(0) <> ERR_OK THEN Read_Tag ' If we get an error, keep trying until the read is successful
FOR idx = 1 TO 4 ' Print data
DEBUG HEX2 buf(idx)
NEXT
DEBUG CR
DEBUG "Writing and verifying data to tag..."
Write_Tag:
SEROUT RFID_TX, Baud, ["!RW", RFID_Write, 3, $FE, $ED, $BE, $EF] ' Write $FEEDBEEF into address 4 (user EEPROM area)
SERIN RFID_RX, Baud, [buf(0)] ' Wait for status byte
IF buf(0) <> ERR_OK THEN Write_Tag ' If we get an error, keep trying until the write is successful
DEBUG "Success!", CR
DEBUG "End of test.", CR
END
' -----[ End of File ]----------------------------------------------------
Im new in programming .... do I need something like :
#include <SoftwareSerial.h>
int val = 0;
char code[10];
int bytesread = 0;
#define rxPin 7
#define txPin 6
// RFID reader SOUT pin connected to Serial RX pin at 2400bps to pin8
void setup()
{
Serial.begin(9600); // Hardware serial for Monitor 2400bps
}
void loop()
{
SoftwareSerial RFID = SoftwareSerial(rxPin,txPin);
RFID.begin(9600);
RFID.println("RFID_Read"); // ????????????
if((val = RFID.read()) == 10)
{ // check for header
bytesread = 0;
while(bytesread<10)
{ // read 10 digit code
val = RFID.read();
if((val == 10)||(val == 13))
{ // if header or stop bytes before the 10 digit reading
break; // stop reading
}
code[bytesread] = val; // add the digit
bytesread++; // ready to read next digit
}
if(bytesread == 10)
{ // if 10 digit read is complete
Serial.print("TAG code is: "); // possibly a good TAG
Serial.println(code); // print the TAG code
}
bytesread = 0;
delay(500); // wait for a second
}
}
You know that loop is executed in an endless loop, right?
Creating a new instance of SoftwareSerial on every pass is not really a good idea.
You should be using NewSoftSerial. SoftwareSerial is obsolete.
Does your RFID reader have some capability to display messages? If not, why are you writing to it?
RFID.println("RFID_Read"); // ????????????
code is a character array, not a string. The difference between a string and a character array is that a string is a character array THAT IS NULL TERMINATED. Your array is not NULL terminated. Therefore it is not a string, and can be treated, by Serial.println as one.
You need to make code bigger, and store '\0' in code[bytesread] after storing the value read from the serial port and incrementing bytesread.
You should be using NewSoftSerial. SoftwareSerial is obsolete.
That's what I thought too, until I tried to use it with a Mega. As far as I can tell, reading characters doesn't work on a Mega. In fact, on the Arduiniana web page they list support for Arduino Mega under "Upcoming Improvements".
--
The Quick Shield: breakout all 28 pins to quick-connect terminals
With 4 hardware serial ports on the Mega, why would you need software serial ports, too?
I want to connect more than 5 rfid modules... thats why software serial!
I can figure out what to do ...
can some one the by steps what to do.... because Im out of ideas !
Communication: asynchronous serial 9600 bps, (8N1); 5 V TTL-level, non-inverted
must send a three-byte header string of !RW (in ASCII), followed by the desired single-byte command (in hexadecimal)
the command will be RFID_Read
now , what do I have to write ? to start reading tags ? help me please , I dont know what to do ? I'm new in this stuff!
I've never used it with a Mega... but I'm pretty sure the Parallax RFID reader works at 2400 bps, not 9600 bps so that might be your first problem.
Get your read on;
http://www.arduino.cc/playground/Learning/PRFID
I'll be glad if this whas the problem, but in do doc. is written so ! http://www.parallax.com/Portals/0/Downloads/docs/prod/rf/28440-RFIDReadWrite-v1.0.pdf