RFID and Wemos D1 mini (1)

I wanted to connect an RFID reader to my home network.
Therefore i used a ESP8266, more specific the Wemos D1 mini Wifi module.

Test 1 (fail)

I found a project on http://www.instructables.com/id/WiFi-RFID-Reader/ using a Wemos D1 mini. The exact info about the pins was missing.
As a test i created the circuit as a test on a breadboard using the Wemos D1 mini pin info on https://escapequotes.net/esp8266-wemos-d1-mini-pins-and-diagram/. (See also this picture with Wemos D1 mini connections)

RFID	ESP8266	Wemos D1 mini
RST	GPIO05 (free GPIO)	D1
SS	GPIO4 (free GPIO)	D2
MOSI	GPIO13 (HW SPI)	D7
MISO	GPIO12 (HW SPI)	D6
SCK	GPIO14 (HW SPI)	D5
GND	GND	G
3.3V	3.3V	3V3

The instructional also contains software to read basic RFID info and send it over the serial (usb) line.

define RFID module

#include "MFRC522.h"
#define RST_PIN 15 // RST-PIN for RC522 - RFID - SPI - Modul GPIO15 
#define SS_PIN  2  // SDA-PIN for RC522 - RFID - SPI - Modul GPIO2
MFRC522 mfrc522(SS_PIN, RST_PIN);   // Create MFRC522 instance

Initialize RFID module

void setup() {
  Serial.begin(9600);    // Initialize serial communications
  SPI.begin();           // Init SPI bus
  mfrc522.PCD_Init();    // Init MFRC522 
}

Read RFID tag

void loop() { 
  // Look for new cards
  if ( ! mfrc522.PICC_IsNewCardPresent()) {
    delay(50);
    return;
  }
  // Select one of the cards
  if ( ! mfrc522.PICC_ReadCardSerial()) {
    delay(50);
    return;
  }
  // Show some details of the PICC (that is: the tag/card)
  Serial.print(F("Card UID:"));
  dump_byte_array(mfrc522.uid.uidByte, mfrc522.uid.size);
  Serial.println();
}

// Helper routine to dump a byte array as hex values to Serial
void dump_byte_array(byte *buffer, byte bufferSize) {
  for (byte i = 0; i < bufferSize; i++) {
    Serial.print(buffer[i] < 0x10 ? " 0" : " ");
    Serial.print(buffer[i], HEX);
  }
}

Unfortunate the example above did not working for me. I got output on the terminal, however there was a message about perhaps bad connections.

Test 2 (succes)

More succesfull was the next example that  i found this on github:
https://github.com/Jorgen-VikingGod/ESP8266-MFRC522

Wiring RFID RC522 module

The following table shows the typical pin layout used:

Signal	MFRC522	WeMos D1 mini	NodeMcu	Generic
RST/Reset	RST	D3 [1]	D3 [1]	GPIO-0 [1]
SPI SS	SDA [3]	D8 [2]	D8 [2]	GPIO-15 [2]
SPI MOSI	MOSI	D7	D7	GPIO-13
SPI MISO	MISO	D6	D6	GPIO-12
SPI SCK	SCK	D5	D5	GPIO-14

• [1] (1, 2) Configurable, typically defined as RST_PIN in sketch/program.
• [2] (1, 2) Configurable, typically defined as SS_PIN in sketch/program.
• [3] The SDA pin might be labeled SS on some/older MFRC522 boards (including the one i used)

Define RFID module

#include "MFRC522.h"
#define RST_PIN 5 // RST-PIN for RC522 - RFID - SPI - Modul GPIO5 
#define SS_PIN 4 // SDA-PIN for RC522 - RFID - SPI - Modul GPIO4 
MFRC522 mfrc522(SS_PIN, RST_PIN); // Create MFRC522 instance

Initialize RFID module

void setup() {
  Serial.begin(115200);    // Initialize serial communications
  SPI.begin();          // Init SPI bus
  mfrc522.PCD_Init();    // Init MFRC522
}

Read RFID tags

void loop() { 
  // Look for new cards
  if ( ! mfrc522.PICC_IsNewCardPresent()) {
    delay(50);
    return;
  }
  // Select one of the cards
  if ( ! mfrc522.PICC_ReadCardSerial()) {
    delay(50);
    return;
  }
  // Show some details of the PICC (that is: the tag/card)
  Serial.print(F("Card UID:"));
  dump_byte_array(mfrc522.uid.uidByte, mfrc522.uid.size);
  Serial.println();
}

// Helper routine to dump a byte array as hex values to Serial
void dump_byte_array(byte *buffer, byte bufferSize) {
  for (byte i = 0; i < bufferSize; i++) {
    Serial.print(buffer[i] < 0x10 ? " 0" : " ");
    Serial.print(buffer[i], HEX);
  }
}

THis did work and i expected that was a good starting point for the rest of my project.