RFID with a TFT lcd shield

Using Arduino Project Guidance
1

Hello,

I'd like to know if this will work. I have an arduino UNO, with a basic protoshield stacked upon it, and a 2.8" TFT LCD screen shield stacked on the protoshield. I want to include a RFID rc522 to the project, but I am not sure which pins to connect to? The TFT screen pretty much uses all of the pins, which is why I got the protoshield to be able to connect to multiple pins. However, the RFID pinout is telling me to use 9,10,11,12, & 13, with the 3.3 V, and GND. If I connect the 11, 12, & 13 pins, they should be fine being doubled up, because they are the MISO, MOSI, and SCK, correct? But what about pins 9 and 10? I believe the TFT screen uses those, so would it be best for me to connect to and code the RFID SS and RST to some other pins, say 8 and 7, or 3 and 4, or any of the analog ones?? OR how can I change the code for the TFT screen to use a different pinout, seeing that it is currently connected to all the pins anyway??

2

You are lacking a lot of detail here.
First what TFT are you using, what voltage is running it and what library is driving it?
Same goes for the RFID, this is normally a 3V3 system so you need to run your Arduino at this voltage or provide some sort of level shifter. Does the TFT have a level shifter built in? If so it is possible that the
Is might interfere with the RFID’s shifter.

In general the RFID reader is an SPI connected and the SPI signals can be shaired with the other two signals being set to use other pins. Does your RFID libiary have a method to say what pins are used?

3

The TFT screen I am using is the Elegoo UNO R3 2.8 Inches TFT Touch Screen. I can attached its user manual to a post. I believe its voltage is the 5V. As far as the library it came with the adafruit_gfx.h and the adafruit_tftlcd.h.

I didn't have documentation with the rfid, it was the MFRC-522 RC522 RFID Radiofrequency IC Card Inducing Sensor Reader for Arduino.
I found the MFRC522.h library for the rfid card.

I have code to try and do what I'd like to see done. Pretty much I would like the project to scan rfid tags I have strategically hidden around a room and on the lcd screen state that it was found or not. The "clock" program is just a visual timer, and should always be counting down from 60 minutes.

#include <Adafruit_GFX.h>    // Core graphics library
#include <Adafruit_TFTLCD.h> // Hardware-specific library

#include <SPI.h>
#include <MFRC522.h>

#define RST_PIN         9           // Configurable, see typical pin layout above
#define SS_PIN          10          // Configurable, see typical pin layout above

MFRC522 mfrc522(SS_PIN, RST_PIN);   // Create MFRC522 instance

#define LCD_CS A3 // Chip Select goes to Analog 3 A3
#define LCD_CD A2 // Command/Data goes to Analog 2 A2
#define LCD_WR A1 // LCD Write goes to Analog 1 A1
#define LCD_RD A0 // LCD Read goes to Analog 0 A0
#define LCD_RESET A4 // Can alternately just connect to Arduino's reset pin A4
#define BLACK   0x0000
#define RED     0xF800
#define YELLOW  0xFFE0
#define WHITE   0xFFFF
#define SAND 0xFFFB //this is one I created to try to get sand color

Adafruit_TFTLCD tft(LCD_CS, LCD_CD, LCD_WR, LCD_RD, LCD_RESET);

//These set up the parameters for the clock program
float sx = 0, sy = 1, mx = 1, my = 0, hx = -1, hy = 0;    // Saved H, M, S x & y multipliers
float sdeg=0, mdeg=0, hdeg=0;
uint16_t osx=120, osy=120, omx=120, omy=120, ohx=120, ohy=120;  // Saved H, M, S x & y coords
uint16_t x0=0, x1=0, y0=0, y1=0;
uint32_t targetTime = 0;                    // for next 1 second timeout
uint8_t hh=0, mm=0, ss=0;  // Get H, M, S from compile time,  set the start times for the countdown
boolean initial = 1;


void setup() {

Serial.begin(9600);                                           
  SPI.begin();                                                  
  mfrc522.PCD_Init();                                              
  Serial.println(F("Read personal data on a MIFARE PICC:"));    
  

uint16_t identifier = tft.readID();
identifier=0x9341;
tft.begin(identifier);

//Create a background fill
tft.fillScreen(BLACK);

// Draw clock face
  tft.fillCircle(120, 120, 118, SAND);
  tft.fillCircle(120, 120, 110, BLACK);
  
// Draw 12 lines
  for(int i = 0; i<360; i+= 30) {
    sx = cos((i-90)*0.0174532925);
    sy = sin((i-90)*0.0174532925);
    x0 = sx*114+120;
    y0 = sy*114+120;
    x1 = sx*100+120;
    y1 = sy*100+120;
    tft.drawLine(x0, y0, x1, y1, SAND);
  }

// Draw 60 dots
  for(int i = 0; i<360; i+= 6) {
    sx = cos((i-90)*0.0174532925);
    sy = sin((i-90)*0.0174532925);
    x0 = sx*102+120;
    y0 = sy*102+120;
    // Draw minute markers
    tft.drawPixel(x0, y0, WHITE);
    
// Draw main quadrant dots
    if(i==0 || i==180) tft.fillCircle(x0, y0, 2, YELLOW);
    if(i==90 || i==270) tft.fillCircle(x0, y0, 2, YELLOW);

//Draw start marker
    tft.fillTriangle(114,0,124,0,119,25,RED);
  }

  tft.fillCircle(120, 121, 3, WHITE);

}


void loop() {
// this first loop will keep the clock counting down from 60 and move accordingly

if (targetTime < millis()) {
    targetTime = millis()+1000;
    ss++;              // Advance second
    if (ss==60) {
      ss=0;
      mm++;            // Advance minute
      if(mm>59) {
        mm=0;
        hh++;          // Advance hour
        if (hh>23) {
          hh=0;
        }
      }
    }

    // Pre-compute hand degrees, x & y coords for a fast screen update
    sdeg = ss*6;                  // 0-59 -> 0-354
    mdeg = mm*6+sdeg*0.01666667;  // 0-59 -> 0-360 - includes seconds
    hdeg = hh*30+mdeg*0.0833333;  // 0-11 -> 0-360 - includes minutes and seconds
    hx = cos((hdeg-90)*0.0174532925);    
    hy = sin((hdeg-90)*0.0174532925);
    mx = cos((mdeg-90)*0.0174532925);    
    my = sin((mdeg-90)*0.0174532925);
    sx = cos((sdeg-90)*0.0174532925);    
    sy = sin((sdeg-90)*0.0174532925);

    if (ss==0 || initial) {
      initial = 0;
// Erase hour and minute hand positions every minute

      tft.drawLine(omx, omy, 120, 121, BLACK);
      omx = mx*84+120;    
      omy = my*84+121;
    }

// Redraw new hand positions, hour and minute hands not erased here to avoid flicker

      osx = sx*90+121;    
      osy = sy*90+121;

      tft.drawLine(omx, omy, 120, 121, WHITE);

}

//This Loop Writes a string text to the arduino tft screen using the serial monitor

Serial.begin(9600);
String serialcommand;
serialcommand = Serial.readString();
tft.setCursor(0,250);
tft.setTextSize(3);  //this size will only fill 13 characters across the screen
tft.setTextColor(SAND);

tft.print(serialcommand);
Serial.print(serialcommand);

//This is the "eraser", the character used to clear the tft screen using the serial monitor, one must enter this in to start a new text, without it overlapping itself.
if(serialcommand == "~") {
  Serial.println(serialcommand);
  tft.fillRect(0,250,300,100,BLACK);
    }

MFRC522::MIFARE_Key key;
  for (byte i = 0; i < 6; i++) key.keyByte[i] = 0xFF;

  //some variables we need
  byte block;
  byte len;
  MFRC522::StatusCode status;

  //-------------------------------------------

  // Look for new cards
  if ( ! mfrc522.PICC_IsNewCardPresent()) {
    return;
  }

  // Select one of the cards
  if ( ! mfrc522.PICC_ReadCardSerial()) {
    return;
  }

  Serial.println(F("**Card Detected:**"));

  //-------------------------------------------

  mfrc522.PICC_DumpDetailsToSerial(&(mfrc522.uid)); //dump some details about the card

  //mfrc522.PICC_DumpToSerial(&(mfrc522.uid));      //uncomment this to see all blocks in hex

  //-------------------------------------------

  Serial.print(F("Name: "));

  byte buffer1[18];

  block = 4;
  len = 18;

  //------------------------------------------- GET FIRST NAME
  status = mfrc522.PCD_Authenticate(MFRC522::PICC_CMD_MF_AUTH_KEY_A, 4, &key, &(mfrc522.uid)); //line 834 of MFRC522.cpp file
  if (status != MFRC522::STATUS_OK) {
    Serial.print(F("Authentication failed: "));
    Serial.println(mfrc522.GetStatusCodeName(status));
    return;
  }

  status = mfrc522.MIFARE_Read(block, buffer1, &len);
  if (status != MFRC522::STATUS_OK) {
    Serial.print(F("Reading failed: "));
    Serial.println(mfrc522.GetStatusCodeName(status));
    return;
  }

  //PRINT FIRST NAME
  for (uint8_t i = 0; i < 16; i++)
  {
    if (buffer1[i] != 32)
    {
      Serial.write(buffer1[i]);
    }
  }
  Serial.print(" ");

  //---------------------------------------- GET LAST NAME

  byte buffer2[18];
  block = 1;

  status = mfrc522.PCD_Authenticate(MFRC522::PICC_CMD_MF_AUTH_KEY_A, 1, &key, &(mfrc522.uid)); //line 834
  if (status != MFRC522::STATUS_OK) {
    Serial.print(F("Authentication failed: "));
    Serial.println(mfrc522.GetStatusCodeName(status));
    return;
  }

  status = mfrc522.MIFARE_Read(block, buffer2, &len);
  if (status != MFRC522::STATUS_OK) {
    Serial.print(F("Reading failed: "));
    Serial.println(mfrc522.GetStatusCodeName(status));
    return;
  }

  //PRINT LAST NAME
  for (uint8_t i = 0; i < 16; i++) {
    Serial.write(buffer2[i] );
  }


  //----------------------------------------

  Serial.println(F("\n**End Reading**\n"));

  delay(1000); //change value if you want to read cards faster

  mfrc522.PICC_HaltA();
  mfrc522.PCD_StopCrypto1();
  
}

2.8inch-TFT-UserManual.pdf (313 KB)

4

I have code to try and do what I'd like to see done.

But that is not right is it. Your loop function is too long and you will find it difficult to see what is going, like the serial begin should not be in the loop function but the setup function.
Also you seem to define an instant of the RFID reader inside the loop function, and don't initialise the reader so that is not going to work.
This comment:-

//This Loop Writes a string text to the arduino tft screen using the serial monitor

Is a nonsense.

Start off with the RFID examples given with the libiary and get that going first. Don't forget the level shifters.

#define RST_PIN         9           // Configurable, see typical pin layout above
#define SS_PIN          10          // Configurable, see typical pin layout above

You haven't changed these like I said to pins that are not used by the screen.