tag read by the library is too short

[MarkusPL0]

I've got RFID card which HEX number is 330092A6D7 (this number gave me a women, who generates cards - she sees such a number in their system). My problem is, that RDM6300 library returns only part of this number - namely 92A6D7. Just for testing I've connected directly my laptop with rdm6300 module (via USB/TTL cable). When talking directly with the rdm6300 module I receive 330092A6D7D0 on the serial monitor. It's the same number which I got + D0 at the end.

How can I modify this library to get full RFID number? thx in advance! Markus.

[arduino12]

Hi,

My librery reads all 32bits of the tag_id into the uint32_t tag_id. You read "330092A6D7" thats 40bits, the first byte "33" is the protocol version and I ignore it here.. I assume all tags are version "33" because that was the case with all of my tags..

So "330092A6D7D0" is 8bit version + 32bits tag_id + 8bit checksum (the 8bit xor of all its previous bytes).

You can just print "33" before every tag-id printing and print them with leading zeros, or change all tag_id from uint32_t to uint64_t and store the extra first byte that I ignored..

Let us know if you do find a tag that doesn't start with "33" because I haven't seen one yet :)

[MarkusPL0]

Hi, thx for your instant answer!

I think the assumption that all 40bit tags begins with 33 is wrong! I've got 5 RFID cards with me that begins with 61 and one keychain which begins with (3800928ee4). Maybe some vendors ignore standard and use all 40 bits for ID. I don't know. In the meantime (I didn't expect you're gonna answer so fast :) I tested another library: https://github.com/arliones/RDM6300-Arduino

This one can handle all bits - the description:

"Driver for RDM6300 RFID reader to Arduino. RDM6300 supports 125KHz tags that store 40-bit IDs. The driver handles the IDs as 64-bit integers (unsigned long long), keeping the 24 MSB always in zero."

tomorrow at work I'm gonna check your fix (changing to uint64_t)

thx!

[MarkusPL0]

Hi, unfortunately changing uint32_t to uint64_t did not help ; there must be something else

[arduino12]

Hi,

Well it seem that those 125kHz tags do use 40bits! 😮

For backward-compatibility I won't change the library because many already use it with 32bits. (If I knew it back then - I would have use all 40bits..)

For 40bits support you need to:

1. Change all tag_id related functions and variables from uint32_t to uint64_t in rdm6300.h and rdm6300.cpp files.

2. Change these lines to store the extra 8bits into the tag_id:

   /* add the first 8bits of tag_id so we get 40bits tag_id */
   buff[3] = 0;
   tag_id |= (uint64_t)strtol(buff + 1, NULL, 16) << 32;
   
   /* xor the tag_id and validate checksum */
   for (uint8_t i = 0; i < 40; i += 8)
       checksum ^= ((tag_id >> i) & 0xFF);

Didn't tested yet, you are welcome to try and write if it worked for you so others can use it :)

[MarkusPL0]

Hi, now it works fine!

take a look at examples below. the difference is clear :) 92a6d7-> 330092a6d7 928ee4 -> 3800928ee4 5c1f3d -> 61005c1f3d thanks a lot! PS maybe it would be good idea to define the bit length in rdm6300.h (with default value of 32) and handle accordingly in rdm6300.cpp?

[arduino12]

Hi,

Thanks for testing! I hope to find some time next month to add that option to go 40bit and test it on my hardware before pushing the changes🙃

Will close this issue once its done. 👍

[mikekgr]

tag_id |= (uint64_t)strtol(buff + 1, NULL, 16) << 32;

Dear Sirs, as far as I understood, the above changes should be done to the source files rdm6300.h and rdm6300.cpp I tried to implement the changes but it was unsuccessful so please can someone give me these modified files ? Just to mention that I am planning to use the library on my Arduino Uno (I state that because of the uint64 that I am not sure that it is support it). Many thanks

[mikekgr]

Hi, now it works fine!

take a look at examples below. the difference is clear :) 92a6d7-> 330092a6d7 928ee4 -> 3800928ee4 5c1f3d -> 61005c1f3d thanks a lot! PS maybe it would be good idea to define the bit length in rdm6300.h (with default value of 32) and handle accordingly in rdm6300.cpp?

@MarkusPL0 can you help me on this? I just want the modified files rdm6300.cpp and rdm6300.h as I understood you have them already modified and working, so please help me. Thanks

[MarkusPL0]

@MarkusPL0 can you help me on this? I just want the modified files rdm6300.cpp and rdm6300.h as I understood you have them already modified and working, so please help me. Thanks

sure rdm6300_modified.zip

[mikekgr]

@MarkusPL0 can you help me on this? I just want the modified files rdm6300.cpp and rdm6300.h as I understood you have them already modified and working, so please help me. Thanks

sure rdm6300_modified.zip

@MarkusPL0 Many thanks for your kind help. Best Regards

[mikekgr]

@MarkusPL0 can you help me on this? I just want the modified files rdm6300.cpp and rdm6300.h as I understood you have them already modified and working, so please help me. Thanks

sure rdm6300_modified.zip

Dear @MarkusPL0 , I overwrite the files library src files from your rdm6300_modified.zip and I tried the simplest example read_to_serial.ino now when I try to compile it (Arduino: 1.8.19 (Windows 10), Board: "Arduino Uno"), I got error in the line 41: Serial.println(rdm6300.get_tag_id(), HEX);
The error says: read_to_serial:41:43: error: call of overloaded 'println(uint64_t, int)' is ambiguous Serial.println(rdm6300.get_tag_id(), HEX);

What I did wrong or what I have to change in the line or sketch?

Thanks

[MarkusPL0]

have you tried casting it directly to String -> String(rdm6300.get_tag_id(), HEX)

[mikekgr]

Dear @MarkusPL0 , I first tester the below unmodified sketch (from the library's examples: read_to_serial), after using the modified library from your supplied zip `

include

include

define RDM6300_RX_PIN 4 // read the SoftwareSerial doc above! may need to change this pin to 10...

define READ_LED_PIN 13

Rdm6300 rdm6300;

void setup() { Serial.begin(115200);

pinMode(READ_LED_PIN, OUTPUT);
digitalWrite(READ_LED_PIN, LOW);

rdm6300.begin(RDM6300_RX_PIN);

Serial.println("\nPlace RFID tag near the rdm6300...");

}

void loop() { / get_new_tag_id returns the tag_id of a "new" near tag, following calls will return 0 as long as the same tag is kept near. / if (rdm6300.get_new_tag_id()) Serial.println(rdm6300.get_tag_id(), HEX);

/* get_tag_id returns the tag_id as long as it is near, 0 otherwise. */
digitalWrite(READ_LED_PIN, rdm6300.get_tag_id());

delay(10);

} then according to your suggestion above, I modified the line from: if (rdm6300.get_new_tag_id()) Serial.println(rdm6300.get_tag_id(), HEX);

` to:

` if (rdm6300.get_new_tag_id()) Serial.println(String(rdm6300.get_tag_id(), HEX));

` but I got the folowing error: C:\Users\Tester\AppData\Local\Temp\arduino_modified_sketch_25707\read_to_serial.ino: In function 'void loop()': read_to_serial:41:50: error: call of overloaded 'String(uint64_t, int)' is ambiguous Serial.println(String(rdm6300.get_tag_id(), HEX));

call of overloaded 'String(uint64_t, int)' is ambiguous

Sorry but I can't find what is wrong, if you can please help me. Thanks

[MarkusPL0]

I was testing it using Wemos D1 board (based on ESP8266). When you change your board to Wemos D1 (or whatever based on ESP8266) this program will compile without problems. On Arduino UNO Board in fact there is an error

it looks like Arduino Print class does not support 64-bit integers. Have a look here, there is a workaround for that

https://github.com/greiman/SdFat/issues/130

[mikekgr]

I was testing it using Wemos D1 board (based on ESP8266). When you change your board to Wemos D1 (or whatever based on ESP8266) this program will compile without problems. On Arduino UNO Board in fact there is an error

it looks like Arduino Print class does not support 64-bit integers. Have a look here, there is a workaround for that

greiman/SdFat#130

Ok now it's clear that there are some limitations in the Arduino Uno and the related. Looking for a workaround I found also a good library that's working fine with Arduino Uno, the library is: https://github.com/RobTillaart/printHelpers/

Again, I want to thank you for your kind support.

Best Regards, Mike Kranidis