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1

I am new to all of this. I am working on an rfid project using an esp32, a rc522 reader and a 16x2 liquid crystal display. I cannot get past the compiling to try and load on the esp32. This is what I am getting;

WARNING: library MFRC522 claims to run on avr, STM32F1, teensy, esp8266, samd architecture(s) and may be incompatible with your current board which runs on esp32 architecture(s).
WARNING: library LiquidCrystal I2C claims to run on avr architecture(s) and may be incompatible with your current board which runs on esp32 architecture(s).
C:\Users\Mike\Documents\Arduino\libraries\MFRC522\src\MFRC522Extended.cpp: In member function 'MFRC522::StatusCode MFRC522Extended::TCL_Transceive(TagInfo*, byte*, byte, byte*, byte*)':
C:\Users\Mike\Documents\Arduino\libraries\MFRC522\src\MFRC522Extended.cpp:824:34: error: ordered comparison of pointer with integer zero ('byte*' {aka 'unsigned char*'} and 'int')
  824 |         if (backData && (backLen > 0)) {
      |                          ~~~~~~~~^~~
C:\Users\Mike\Documents\Arduino\libraries\MFRC522\src\MFRC522Extended.cpp:847:42: error: ordered comparison of pointer with integer zero ('byte*' {aka 'unsigned char*'} and 'int')
  847 |                 if (backData && (backLen > 0)) {
      |                                  ~~~~~~~~^~~

exit status 1

Compilation error: exit status 1

I haven't got a clue and not afraid to admit it. I got the project from a you tuber here : https://www.youtube.com/watch?v=xeHBKi0GLow

Can anyone help me out here??????????

2

it looks as though the statement should be using the dereference operator *

if (backData && (*backLen > 0)) {

looking at my ESP32 code I have used the Arduino_MFRC522v2 library

3

Welcome to the forum

The most significant part of the error message should be obvious to you

The library is not compatible with your processor

4

I have used the MFRC522v2 library on an ESP32
test with SD card and MFRC522

image
image504×568 44.3 KB

some Serial monitor output

ESP32 SD card test - note VCC to 5V

Read MRFC522 RFID card save time and data to SD card
SD Card Type: SDHC
SD Card Size: 14992MB
Listing directory: /
  DIR : System Volume Information
  FILE: test.txt  SIZE: 1048576
  FILE: data.txt  SIZE: 891
Total space: 14984MB
Used space: 2MB
open MRFC522 RFID readerFirmware Version: 0x92 = v2.0
dDeleting file: /data.txt
File deleted

Friday, January 01 2021 01:00:14
 Card UID: ZZ XX FD C2  PICC type: MIFARE 1KB

Friday, January 01 2021 01:00:18
 Card UID: Z0 XF 62 1A  PICC type: MIFARE 1KB

Friday, January 01 2021 01:00:19
 Card UID: Z0 XF 62 1A  PICC type: MIFARE 1KB

Friday, January 01 2021 01:00:22
 Card UID: ZZ XX FD C2  PICC type: MIFARE 1KB

Friday, January 01 2021 01:00:23
 Card UID: ZZ XX FD C2  PICC type: MIFARE 1KB

Friday, January 01 2021 01:02:30
 Card UID: Z0 XF 62 1A  PICC type: MIFARE 1KB
5

People find guns all the time,
How do they know which end to look into ?