mrRFID

Arduino library with support for Melexis MLX90109 RFID tag reader ICs.

This library supports 125 Khz RFID tag readers based on Melexis MLX90109 ICs.

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Example

#include <RFID.h>

#define CLOCK_PIN    13
#define DATA_PIN     12

void onTagRead(const String &tag) {
    Serial.println(tag);
    RFID.begin(CLOCK_PIN, DATA_PIN);
}

void setup() {
    Serial.begin(115200);
    RFID.attach(onTagRead);
}

void loop() {
    RFID.loop();
}

See "RFID_Callback.ino" for the complete example.

Documentation

MLX90109 requires two pin on the MCU side configured as digital inputs: one for CLOCK signal and the other one for DATA signal. All the required initializations are done by the library.

Most of the tag reader IC pins can’t be left floating and they have to be pulled up/down. On the EVB90109_V3 evaluation board pin 3 (SPEED) and pin 7 (MODE)) are connected to 10 (VDD), while pin 6 (MODUR2) is connected to VSS. Pins for Fast Decay and MODUR3 can be left floating since I don’t use fast decay nor on/off modulation in my setup, and regarding MODUR3 components for this aren’t soldered on the evaluation board by default.

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Definitions

RFID_UID_LEN is the binary length of a tag (5 bytes).

Construction and initialization

RFIDClass myRFID (
    uint8_t clockPin,
    uint8_t dataPin
);

Functions

void begin();

void begin(const uint8_t clockPin, const uint8_t dataPin);

Must be called in setup() function.

void loop();

Must be called in loop() function.

RFIDStatus status();

Returns:

a value < 0 if an error has occurred. It could be one of the following:
- RFID_MLX_ERR_TIMEOUT when a timeout error is occurred.
- RFID_MLX_ERR_HPARITY if the horizonatal parity check fails.
- RFID_MLX_ERR_VPARITY if the vertical parity check fails.
- RFID_MLX_ERR_BITSTOP if not bit stop found.
0 if no tag deteted
a value > 0 if a tag is read

void attach(void (*callback)(const String &tag));

Set a callback function called when a tag is read. The tag parameter contains the UID in HEX format.

void uid(uint8_t *dst, const size_t len);

Put the last UID tag read (binary raw values). dst is a byte array pointer of len size to fill with UID data. It must be length at least RFID_UID_LEN (default to 5).

void tag(char *dst, const size_t len);

Put the last UID tag read in HEX string format. dst is a char array pointer of len size to fill with UID data. It must be length at least double RFID_UID_LEN plus 1 for string terminator.

uint8_t uid8(const uint8_t i);

Return the ist element of the last UID tag read.

For any further reading about MLX90109 see details at https://www.melexis.com/en/product/MLX90109/125kHz-RFID-Transceiver. For my tests I used the evaluation board EVB90109_V3 https://www.melexis.com/en/product/evb90109/evaluation-board-mlx90109.

Installation

To install, download the .zip file: https://github.com/markreds81/RFID/archive/master.zip and rename the RFID-master folder to RFID. Move the RFID folder to your Arduino/libraries folder and restart the Arduino IDE. This library should work on Arduino IDE v1.5 and later.

License

This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with this library. If not, see http://www.gnu.org/licenses/.

markreds81 / RFID

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