Add comments to make it easier to understand

ljos · Oct 7, 2013 · 2dc010b · 2dc010b
1 parent 45a84cb
commit 2dc010b
Showing 1 changed file with 19 additions and 0 deletions.
diff --git a/examples/auth_read_write/authenticate.ino b/examples/auth_read_write/authenticate.ino
@@ -8,11 +8,14 @@ MFRC522 nfc(SAD, RST);
 
 void setup() {
   SPI.begin();
+  // Read a fast as possible. There is a limit for how long we are
+  // allowed to read from the tags.
   Serial.begin(115200);
 
   Serial.println("Looking for MFRC522.");
   nfc.begin();
 
+  // Get the firmware version of the RFID chip
   byte version = nfc.getFirmwareVersion();
   if (! version) {
     Serial.print("Didn't find MFRC522 board.");
@@ -34,6 +37,8 @@ void loop() {
   byte serial[5];
   int i, j, pos;
 
+  // Send a general request out into the aether. If there is a tag in
+  // the area it will respond and the status will be MI_OK.
   status = nfc.requestTag(MF1_REQIDL, data);
 
   if (status == MI_OK) {
@@ -43,6 +48,8 @@ void loop() {
     Serial.print(", ");
     Serial.println(data[1], HEX);
 
+    // calculate the anti-collision value for the currently detected
+    // tag and write the serial into the data array.
     status = nfc.antiCollision(data);
     memcpy(serial, data, 5);
 
@@ -53,15 +60,24 @@ void loop() {
     }
     Serial.println(serial[3], HEX);
 
+    // Select the tag that we want to talk to. If we don't do this the
+    // chip does not know which tag it should talk if there should be
+    // any other tags in the area..
     nfc.selectTag(serial);
+
+    // Assuming that there are only 64 blocks of memory in this chip.
     for (i = 0; i < 64; i++) {
+      // Try to authenticate each block first with the A key.
       status = nfc.authenticate(MF1_AUTHENT1A, i, keyA, serial);
       if (status == MI_OK) {
         Serial.print("Authenticated block nb. 0x");
         Serial.print(i, HEX);
         Serial.println(" with key A.");
+        // Reading block i from the tag into data.
         status = nfc.readFromTag(i, data);
         if (status == MI_OK) {
+          // If there was no error when reading; print all the hex
+          // values in the data.
           for (j = 0; j < 15; j++) {
             Serial.print(data[j], HEX);
             Serial.print(", ");
@@ -71,6 +87,8 @@ void loop() {
           Serial.println("Read failed.");
         }
       } else {
+        // If we could not authenticate with the A key, we will try
+        // the B key.
         status = nfc.authenticate(MF1_AUTHENT1B, i, keyB, serial);
         if (status == MI_OK) {
           Serial.print("Authenticated block nb. 0x");
@@ -93,6 +111,7 @@ void loop() {
       }
     }
 
+    // Stop the tag and get ready for reading a new tag.
     nfc.haltTag();
   }
   delay(2000);