Initial commit: project docs and ignore rules

nfc_protocol.cpp

@@ -0,0 +1,69 @@
+#include "nfc_protocol.h"
+
+uint16_t calculateChecksum(const uint8_t* data, size_t length) {
+    uint16_t checksum = 0;
+    for (size_t i = 0; i < length; i++) {
+        checksum += data[i];
+    }
+    return checksum;
+}
+
+bool validateMessage(const CommMessage* msg) {
+    if (msg == nullptr) return false;
+    
+    // Calculate checksum excluding the checksum field itself
+    size_t data_size = sizeof(CommMessage) - sizeof(msg->checksum);
+    uint16_t calculated_checksum = calculateChecksum((const uint8_t*)msg, data_size);
+    
+    return calculated_checksum == msg->checksum;
+}
+
+void printNFCData(const NFCData* data) {
+    if (data == nullptr) return;
+    
+    Serial.println("=== NFC Data ===");
+    Serial.print("UID: ");
+    for (int i = 0; i < data->uid_length; i++) {
+        if (data->uid[i] < 0x10) Serial.print("0");
+        Serial.print(data->uid[i], HEX);
+        if (i < data->uid_length - 1) Serial.print(" ");
+    }
+    Serial.println();
+    
+    Serial.print("UID Length: ");
+    Serial.println(data->uid_length);
+    
+    Serial.print("SAK: 0x");
+    if (data->sak < 0x10) Serial.print("0");
+    Serial.println(data->sak, HEX);
+    
+    Serial.print("ATQA: 0x");
+    if (data->atqa[0] < 0x10) Serial.print("0");
+    Serial.print(data->atqa[0], HEX);
+    Serial.print(" 0x");
+    if (data->atqa[1] < 0x10) Serial.print("0");
+    Serial.println(data->atqa[1], HEX);
+    
+    Serial.print("Tag Type: ");
+    Serial.println(data->tag_type);
+    
+    Serial.print("Data Length: ");
+    Serial.println(data->data_length);
+    
+    Serial.print("Timestamp: ");
+    Serial.println(data->timestamp);
+    
+    if (data->data_length > 0) {
+        Serial.print("Raw Data: ");
+        for (int i = 0; i < data->data_length && i < 32; i++) {
+            if (data->raw_data[i] < 0x10) Serial.print("0");
+            Serial.print(data->raw_data[i], HEX);
+            Serial.print(" ");
+        }
+        if (data->data_length > 32) {
+            Serial.print("... (truncated)");
+        }
+        Serial.println();
+    }
+    Serial.println("================");
+}