Hello, I am doing a project that involves using the arduino uno and the ethernet shield 2 with the sunfounder rfid-rc522 reader for my project. This involves me scanning the card and it uploads to a google spreadsheet. I think it works but it simply does not scan my card as valid even though I typed it in. I basically got this project from this link
https://create.arduino.cc/projecthub/embedotronics-technologies/attendance-system-based-on-arduino-and-google-spreadsheet-105621?ref=search&ref_id=rfid&offset=54
I would ask the creator but he won't respond to me. The code is attached of his that I modified to meet my standards.
I also attached the screenshot of what happens when I scan the tags.
If you help me on this I appreciate you. 
Testbeta2.ino (3.3 KB)
Read How to use this forum, and post your sketch on the forum using code tags.
You will never recognize a tag or card- because that's the way the code is written.
Consider the logic of your nested if statements.
if card 1 matches, AND card 2 matches, AND card 3 matches, AND card 4 matches, then you have a match.
Try changing the second through the third if to elseif, then the logic reads card 1 OR card 2 OR card 3 OR card 4.
void loop(){
int m=0;
if(!rfid.PICC_IsNewCardPresent())
return;
if(!rfid.PICC_ReadCardSerial())
return;
for(i=0;i<4;i++)
{
id_temp[0][i]=rfid.uid.uidByte[i];
delay(50);
}
for(i=0;i<No_Of_Card;i++)
{
if(id[i][0]==id_temp[0][0])
{
if(id[i][1]==id_temp[0][1])
{
if(id[i][2]==id_temp[0][2])
{
if(id[i][3]==id_temp[0][3])
{
Serial.print("your card no :");
for(int s=0;s<4;s++)
{
Serial.print(rfid.uid.uidByte[s]);
Serial.print(" ");
I don't really know how to setup elseif (I am a student), but I don't know why there are ids 0-3 when it only has three card data slots, and Im only using 2 valid ones, the 3rd one was already there from the guys project.
This is the card code
byte id[No_Of_Card][4]={
{204,389,56,51}, //RFID NO-1
{3010,9,31,52}, //RFID NO-2
{142,76,58,42} //RFID NO-3
};
byte id_temp[3][3];
byte i;
int j=0;
I appreciate your help with me, as I don't know much about this code.
RTFM
I won't write the code for you, but I will answer specific questions. I already showed you where your problem is and how to fix it.
for(i=0;i<No_Of_Card;i++)
{
if(id[i][0]==id_temp[0][0]) {
Serial.print("your card no :");
for(int s=0;s<4;s++)
{
Serial.print(rfid.uid.uidByte[s]);
Serial.print(" ");
}
Serial.println("\nValid Person");
Sending_To_spreadsheet();
j=0;
rfid.PICC_HaltA(); rfid.PCD_StopCrypto1(); return;
}
else if(id[i][1]==id_temp[0][1]) {
Serial.print("your card no :");
for(int s=0;s<4;s++)
{
Serial.print(rfid.uid.uidByte[s]);
Serial.print(" ");
}
Serial.println("\nValid Person");
Sending_To_spreadsheet();
j=0;
rfid.PICC_HaltA(); rfid.PCD_StopCrypto1(); return;
}
else if(id[i][2]==id_temp[0][2]) {
Serial.print("your card no :");
for(int s=0;s<4;s++)
{
Serial.print(rfid.uid.uidByte[s]);
Serial.print(" ");
}
Serial.println("\nValid Person");
Sending_To_spreadsheet();
j=0;
rfid.PICC_HaltA(); rfid.PCD_StopCrypto1(); return;
}
else if(id[i][3]==id_temp[0][3])
{
Serial.print("your card no :");
for(int s=0;s<4;s++)
{
Serial.print(rfid.uid.uidByte[s]);
Serial.print(" ");
}
Serial.println("\nValid Person");
Sending_To_spreadsheet();
j=0;
rfid.PICC_HaltA(); rfid.PCD_StopCrypto1(); return;
}
else
{j++;
if(j==No_Of_Card)
{
Serial.println("Not a valid Person");
Sending_To_spreadsheet();
j=0;
}
}
}
I changed them to elseif statements and it still is saying that it is not a valid person so I dont know what Im doing wrong
