c++ - 如何将我的 rfid 卡的 uid 存储在字符串中?
问题描述
我是 C++ 和 arduino 的大菜鸟,但这并不能阻止我尝试很酷的项目。我有一个 arduino mega 2560 v3。我想做一个简单的 rfid 扫描仪,所以当扫描到正确的卡时,它会关闭我的电路。这是我的代码,它来自我的工具包中包含的教程指南,这是 Elegoo 为 mega 2560 提供的最完整的入门工具包。
//www.elegoo.com
//2016.12.09
/*
* --------------------------------------------------------------------------------------------------------------------
* Example to change UID of changeable MIFARE card.
* --------------------------------------------------------------------------------------------------------------------
* This is a MFRC522 library example; for further details and other examples see: https://github.com/miguelbalboa/rfid
*
* This sample shows how to set the UID on a UID changeable MIFARE card.
* NOTE: for more informations read the README.rst
*
* @author Tom Clement
* @license Released into the public domain.
*
* Typical pin layout used:
* -----------------------------------------------------------------------------------------
* MFRC522 Arduino Arduino Arduino Arduino Arduino
* Reader/PCD Uno Mega Nano v3 Leonardo/Micro Pro Micro
* Signal Pin Pin Pin Pin Pin Pin
* -----------------------------------------------------------------------------------------
* RST/Reset RST 9 5 D9 RESET/ICSP-5 RST
* SPI SS SDA(SS) 10 53 D10 10 10
* SPI MOSI MOSI 11 / ICSP-4 51 D11 ICSP-4 16
* SPI MISO MISO 12 / ICSP-1 50 D12 ICSP-1 14
* SPI SCK SCK 13 / ICSP-3 52 D13 ICSP-3 15
*/
#include <SPI.h>
#include <MFRC522.h>
#define RST_PIN 5 // Configurable, see typical pin layout above
#define SS_PIN 53 // Configurable, see typical pin layout above
MFRC522 mfrc522(SS_PIN, RST_PIN); // Create MFRC522 instance
/* Set your new UID here! */
#define NEW_UID {0xDE, 0xAD, 0xBE, 0xEF}
MFRC522::MIFARE_Key key;
void setup() {
Serial.begin(9600); // Initialize serial communications with the PC
while (!Serial); // Do nothing if no serial port is opened (added for Arduinos based on ATMEGA32U4)
SPI.begin(); // Init SPI bus
mfrc522.PCD_Init(); // Init MFRC522 card
Serial.println(F("Warning: this example overwrites the UID of your UID changeable card, use with care!"));
// Prepare key - all keys are set to FFFFFFFFFFFFh at chip delivery from the factory.
for (byte i = 0; i < 6; i++) {
key.keyByte[i] = 0xFF;
}
}
// Setting the UID can be as simple as this:
//void loop() {
// byte newUid[] = NEW_UID;
// if ( mfrc522.MIFARE_SetUid(newUid, (byte)4, true) ) {
// Serial.println("Wrote new UID to card.");
// }
// delay(1000);
//}
// But of course this is a more proper approach
void loop() {
// Look for new cards, and select one if present
if ( ! mfrc522.PICC_IsNewCardPresent() || ! mfrc522.PICC_ReadCardSerial() ) {
delay(50);
return;
}
// Now a card is selected. The UID and SAK is in mfrc522.uid.
// Dump UID
Serial.print(F("Card UID:"));
for (byte i = 0; i < mfrc522.uid.size; i++) {
Serial.print(mfrc522.uid.uidByte[i] < 0x10 ? " 0" : " ");
//String userid = mfrc522.uid.uidByte[i] < 0x10 ? " 0" : " ";
Serial.print(mfrc522.uid.uidByte[i], HEX);
}
Serial.println();
// Dump PICC type
// MFRC522::PICC_Type piccType = mfrc522.PICC_GetType(mfrc522.uid.sak);
// Serial.print(F("PICC type: "));
// Serial.print(mfrc522.PICC_GetTypeName(piccType));
// Serial.print(F(" (SAK "));
// Serial.print(mfrc522.uid.sak);
// Serial.print(")\r\n");
// if ( piccType != MFRC522::PICC_TYPE_MIFARE_MINI
// && piccType != MFRC522::PICC_TYPE_MIFARE_1K
// && piccType != MFRC522::PICC_TYPE_MIFARE_4K) {
// Serial.println(F("This sample only works with MIFARE Classic cards."));
// return;
// }
// Set new UID
byte newUid[] = NEW_UID;
if ( mfrc522.MIFARE_SetUid(newUid, (byte)4, true) ) {
Serial.println(F("Wrote new UID to card."));
}
// Halt PICC and re-select it so DumpToSerial doesn't get confused
mfrc522.PICC_HaltA();
if ( ! mfrc522.PICC_IsNewCardPresent() || ! mfrc522.PICC_ReadCardSerial() ) {
return;
}
// Dump the new memory contents
Serial.println(F("New UID and contents:"));
mfrc522.PICC_DumpToSerial(&(mfrc522.uid));
delay(2000);
}
在打印 uid 的 for 循环中,我尝试将这行代码将 uid 存储在字符串中。String userid = mfrc522.uid.uidByte[i] < 0x10 ? " 0" : " ";
但这没有用。
因此,快速回顾一下我可以使用的帮助是,我需要将 uid 存储在一个字符串中,有一个 if 语句来确定 uid 是否会让我通过,以及接受 uid 将如何关闭电路。我没有想到特定的电路,但是一旦解决了这个问题,我就会制作一个。谢谢。对不起,如果答案很明显,这是一个愚蠢的问题。此外,如果有助于更轻松地回答我的问题,您可以使用我的 uid,即 93 D1 4E 49 作为示例。
解决方案
尝试这样的事情:
String userid;
for (byte i = 0; i < mfrc522.uid.size; i++) {
Serial.print(mfrc522.uid.uidByte[i], HEX);
userid += String(mfrc522.uid.uidByte[i], HEX);
}
Serial.println(userid );
如果那对您没有帮助,我想这是一些解决方案。
推荐阅读
- r - 如何找到并绘制不同的可信区间?
- qt - Qtquick - 未找到 QML 模块
- c++ - 如何在 C++ 中解析逗号分隔的字符串,其中一些元素用逗号引用?
- python - 对 asyncpg 连接池使用“async with”时有关 __aexit__ 的属性错误
- vue.js - 部署 Vue.js 应用程序后下载 PDF 的问题
- python - 从文本文件中查找具有最小值和最大值的行以及您的行号(获取值错误浮点类型)
- mysql - SELECT COUNT with LIKE 给出奇怪的结果
- reactjs - redux 工具包 1.5.1 进行深度复制,但 8.0.4 immer 的校准产品在 react-native android 中不起作用
- c++ - 我需要拆分一串字符“AAABCAAABCDEAA”,这样它会导致“AA”“ABCAA”“ABCDEAA”
- javascript - 暗模式设置为本地存储