to colorize a colorful pixel with a simple touch using nfc technology

Dependencies:   Chainable_RGB_LED mbed

use Arch, NFC Shield and Grove - Chainable RGB LED to DIY a touch pixel. Then use an Android with NFC support to colorize it.

The project is on https://github.com/Seeed-Studio/TouchPixel

Revision:
0:88960f3eeb2c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/nfc/emulatetag.h	Fri Dec 27 01:46:32 2013 +0000
@@ -0,0 +1,71 @@
+/**************************************************************************/
+/*!
+    @file     emulatetag.h
+    @author   Armin Wieser
+    @license  BSD
+
+    Implemented using NFC forum documents & library of libnfc
+*/
+/**************************************************************************/
+
+#ifndef __EMULATETAG_H__
+#define __EMULATETAG_H__
+
+#include "PN532.h"
+
+#define NDEF_MAX_LENGTH 128  // altough ndef can handle up to 0xfffe in size, arduino cannot.
+typedef enum {COMMAND_COMPLETE, TAG_NOT_FOUND, FUNCTION_NOT_SUPPORTED, MEMORY_FAILURE, END_OF_FILE_BEFORE_REACHED_LE_BYTES} responseCommand;
+
+class EmulateTag{
+
+public:
+EmulateTag(PN532Interface &interface) : pn532(interface), uidPtr(0), tagWrittenByInitiator(false), tagWriteable(true), updateNdefCallback(0) { }
+  
+  bool init();
+
+  bool emulate(const uint16_t tgInitAsTargetTimeout = 0);
+
+  /*
+   * @param uid pointer to byte array of length 3 (uid is 4 bytes - first byte is fixed) or zero for uid 
+   */
+  void setUid(uint8_t* uid = 0);
+
+  void setNdefFile(const uint8_t* ndef, const int16_t ndefLength);
+
+  void getContent(uint8_t** buf, uint16_t* length){
+    *buf = ndef_file + 2; // first 2 bytes = length
+    *length = (ndef_file[0] << 8) + ndef_file[1];
+  }
+
+  bool writeOccured(){
+    return tagWrittenByInitiator;
+  }
+
+  void setTagWriteable(bool setWriteable){
+    tagWriteable = setWriteable;
+  }
+
+  uint8_t* getNdefFilePtr(){
+    return ndef_file;
+  }
+
+  uint8_t getNdefMaxLength(){
+    return NDEF_MAX_LENGTH;
+  }
+
+  void attach(void (*func)(uint8_t *buf, uint16_t length)) {
+    updateNdefCallback = func;
+  };
+
+private:
+  PN532 pn532;
+  uint8_t ndef_file[NDEF_MAX_LENGTH];
+  uint8_t* uidPtr;
+  bool tagWrittenByInitiator;
+  bool tagWriteable;
+  void (*updateNdefCallback)(uint8_t *ndef, uint16_t length);
+
+  void setResponse(responseCommand cmd, uint8_t* buf, uint8_t* sendlen, uint8_t sendlenOffset = 0);
+};
+
+#endif