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→Can the PN532 read Tag-It tags from TI?
No. The PN532 is designed to be used with [http://en.wikipedia.org/wiki/ISO/IEC_14443 ISO14443] tags, with Mifare Classic probably the most common general-purpose tag type in use. For more information on supported tags see [http://www.libnfc.org/documentation/hardware/tags/iso14443 http://www.libnfc.org/documentation/hardware/tags/iso14443] or search for information on the common Mifare tag family based on ISO1443A.
No. The PN532 is designed to be used with [http://en.wikipedia.org/wiki/ISO/IEC_14443 ISO14443] tags, with Mifare Classic probably the most common general-purpose tag type in use. For more information on supported tags see [http://www.libnfc.org/documentation/hardware/tags/iso14443 http://www.libnfc.org/documentation/hardware/tags/iso14443] or search for information on the common Mifare tag family based on ISO1443A.
{{PN532-RFID-NFC-TRAILER}}
{{PN532-RFID-NFC-TRAILER}}
== Can I set a delay calling readPassiveTargetID()? ==
Note: This question only applies to the [https://github.com/adafruit/Adafruit_NFCShield_I2C I2C Library]. The [https://github.com/adafruit/Adafruit-PN532 SPI library] doesn't handle the timing the same way.
readPassiveTargetID() intentionally waits around in a blocking delay until a card enters the magnetic field. The reason for this blocking delay is to ensure a well-understood command/response flow. Once the magnetic field is activated and a read request is sent via readPassiveTargetID, you can keep sending new commands to the PN532, but the moment a card or tag enters the field, the PN532 will send a response to the initial read request, even if it's in the middle of some other response or activity. To avoid having to debug this in SW, a blocking delay was implemented to keep the command/response pattern as clear as possible.
As a workaround to this blocking-delay limitation, '''setPassiveActivationRetries(maxRetries)''' was added to the latest NFC libraries to allow you to set a specific timeout after read requests.
By default, the PN532 will wait forever for a card to enter the field. By specifying a fixed number of retries via '''MxRtyPassiveActivation''' (see UM section 7.3.1 describing the '''RFConfiguration''' register, specifically CfgItem 5) the PN532 will abort the read request after specified number of attempts, and you can safely send new commands without worrying about mixing up response frames. To wait forever, set MxRtyPassiveActivation to 0xFF. To timeout after a fixed number of retries, set MxRtyPassiveActivation to anything less than 0xFF.
Example Sketch:
<nowiki>#include <Wire.h>
#include <Adafruit_NFCShield_I2C.h>
#define IRQ (2)
#define RESET (3) // Not connected by default on the NFC Shield
Adafruit_NFCShield_I2C nfc(IRQ, RESET);
void setup(void) {
Serial.begin(115200);
Serial.println("Hello!");
nfc.begin();
uint32_t versiondata = nfc.getFirmwareVersion();
if (! versiondata) {
Serial.print("Didn't find PN53x board");
while (1); // halt
}
// Got ok data, print it out!
Serial.print("Found chip PN5"); Serial.println((versiondata>>24) & 0xFF, HEX);
Serial.print("Firmware ver. "); Serial.print((versiondata>>16) & 0xFF, DEC);
Serial.print('.'); Serial.println((versiondata>>8) & 0xFF, DEC);
// Set the max number of retry attempts to read from a card
// This prevents us from waiting forever for a card, which is
// the default behaviour of the PN532.
nfc.setPassiveActivationRetries(0xFF);
// configure board to read RFID tags
nfc.SAMConfig();
Serial.println("Waiting for an ISO14443A card");
}
void loop(void) {
boolean success;
uint8_t uid[] = { 0, 0, 0, 0, 0, 0, 0 }; // Buffer to store the returned UID
uint8_t uidLength; // Length of the UID (4 or 7 bytes depending on ISO14443A card type)
// Wait for an ISO14443A type cards (Mifare, etc.). When one is found
// 'uid' will be populated with the UID, and uidLength will indicate
// if the uid is 4 bytes (Mifare Classic) or 7 bytes (Mifare Ultralight)
success = nfc.readPassiveTargetID(PN532_MIFARE_ISO14443A, &uid[0], &uidLength);
if (success) {
Serial.println("Found a card!");
Serial.print("UID Length: ");Serial.print(uidLength, DEC);Serial.println(" bytes");
Serial.print("UID Value: ");
for (uint8_t i=0; i < uidLength; i++)
{
Serial.print(" 0x");Serial.print(uid[i], HEX);
}
Serial.println("");
// Wait 1 second before continuing
delay(1000);
}
else
{
// PN532 probably timed out waiting for a card
Serial.println("Timed out waiting for a card");
}
}</nowiki>
== Hey wait ... isn't there something funny with the SVDD pin? ==
Indeed, good eye! Unfortunately, both v1.0 and v1.3 of the breakout boards have a problem on the schematic. SVDD is connected directly to VDD, but should be left floating since it is used to power secure modules. This has no effect on the functionality of the boards, but does cause some extra current to be drawn. It will be fixed on the next revision of the board, but if you require the use of the secure modules (rare), you can simply cut the trace to the left of C22, which is the cap connected to SVDD (just follow the trace straight up from pin 37).
== Are there any special requirements to use the PN532 Breakout with the Due? ==
While the libraries do not officially support the Due yet, some customers have been able to get them working with some minor changes to the library.
We recommend using the I2C libraries with both the shield and the breakout boards since the I2C library represents the latest code from Adafruit, and the shield version should work without too much effort.
There is one caveat combining the breakout, I2C and the Due, though: '''The Due includes pullup resistors for I2C0 (SCL0 and SDA1), but there are no pullups resistors on SCL1 and SDA1. SCL1/SDA1''' are the pins used as replacements for the Uno I2C pins (the pins used on standard shields), so you will need to add two 1.5K pullups on SCL1 and SDA1 to use the breakout board with I2C1 and the Due. Simply solder two 1.5K resistors, one from SCL1 to 3V3 and another from SDA1 to 3.3V, and then connect the board the same way you would with an Uno.
'''This issue only applies to the PN532 Breakout board since the PN532 shield includes I2C pullup resistors right on board'''.