RFID Reader M6E Nano's PCB antenna works but external UHF RFID Antenna doesn't

Sensors NFC & RFID
1

Dear amateurs of electronics,

I am using a Simultaneous RFID Tag Reader (SEN-14066 M6E Nano, as a shield for the Arduino Uno) with the UHF RFID Antenna (RP-TNC) WRL-14131 in order to read Ultra-Small UHF RFID Tag Rain (KIT-16464).

PCB antenna of M6E Nano reads perfectly Ultra-Small UHF RFID tags (applying Example1 Constant Read sketch). After switching the blobs of solder between PCB and external antennas, UHF RFID Antenna (RP-TNC) doesn’t read tags. I re-enabled the PCB antenna and the reader immediately worked again. I have used two brand new interface cables to define whether cables are defective, it didn’t help. The project is powered through Arduino with a power supply of 9V 1A.

  1. Is there something in the hardware set-up that has to be rearranged? Is there anything specific that has to be considered when using UHF RFID Antenna (RP-TNC) WRL-14131?

  2. Is there something in software I need to change e.g. in the Example1 Constant Read sketch? Or add a piece of code that e.g. enables the external antenna?

Best regards,

Eduard

2

Dear Sparkfun specialists,

Could you kindly test the project set-up where RFID ReaderM6E Nano with UHF RFID Antenna (RP-TNC) WRL-14131 are used to read Ultra-Small UHF RFID Tag Rain (KIT-16464)?

If it perfectly functions, please describe how it has been achieved, and what reasons could prevent the tags reading.

Best regards,

Eduard

3

hi

I am not Sparkfun, but have done extensive work on this board. There is no-software setting, no other hardware setting needed. Only switch the solder blob between internal and external (as you did already). Do not connect them both at the same time. There are a couple of points that come to mind to check :

  1. The external antenna could be broken.

2 . A connection issue with the wires. although you had already exchanged the wires, I have seen issues with the small on-board RF that the connection was not made. If you have an ohm meter, try to see whether you can measure the cables, the antenna and connection.

  1. The Nano is very sensitive to power. What happens is you connect the external antenna, connect VCC with USB to a PC (taken VCC from the PC). Keep 500dBM max for reading. Maybe enable debug and see what happens.

  2. As you use 9V /1A power, how did you connect ? Is the RFID used as shield or stand-alone?

4

Thanks for your response, Paul.

  1. The external antenna could be broken.

→ In process of getting a new one…

2 . A connection issue with the wires. although you had already exchanged the wires, I have seen issues with the small on-board RF that the connection was not made. If you have an ohm meter, try to see whether you can measure the cables, the antenna and connection.

→ ohm meter shows resistance in cables and connectors but doesn’t in antenna.

  1. The Nano is very sensitive to power. What happens is you connect the external antenna, connect VCC with USB to a PC (taken VCC from the PC). Keep 500dBM max for reading. Maybe enable debug and see what happens.

→ Could you explain how can I enable debug and evaluate the results?

  1. As you use 9V /1A power, how did you connect ? Is the RFID used as shield or stand-alone?

→ I use a wall adapter to power Arduino, RFID is used as its shield. And connecting USB to PC to read the serial monitor.

Best regards,

Eduard

5

Thanks

To your question about debugging. Use attached example1, set your serial, set DEBUG as 1.

Example1_Constant_Read.zip (2.78 KB)

6

Thank you, Paul!

When #define DEBUG 0

COM readings the following:

Example1: constant read

Module continuously reading. Asking it to stop…

Press a key to begin scanning for tags.

Scanning

Scanning

Scanning

last three lines are repeated continuously even if the tags touch the antenna

When #define DEBUG 1

COM readings:

Example1: constant read

sendCommand: [FF] [00] [03] [1D] [0C]

response: [FF] [00] [22] [04] [00]

Wrong opcode response

sendCommand: [FF] [03] [2F] [00] [00] [02] [5E] [86]

Time out 1: No response from module

Module continuously reading. Asking it to stop…

sendCommand: [FF] [00] [03] [1D] [0C]

response: [FF] [14] [03] [00] [00] [14] [12] [08] [00] [30] [00] [00] [02] [20] [19] [06] [10] [01] [09] [01] [11] [00] [00] [00] [10]

sendCommand: [FF] [02] [93] [00] [05] [51] [7D]

response: [FF] [00] [93] [00] [00]

sendCommand: [FF] [02] [91] [01] [01] [70] [3B]

response: [FF] [00] [91] [00] [00]

sendCommand: [FF] [01] [97] [0D] [4B] [B0]

response: [FF] [00] [97] [00] [00]

sendCommand: [FF] [02] [92] [01] [F4] [40] [AD]

response: [FF] [00] [92] [00] [00]

Press a key to begin scanning for tags.

sendCommand: [FF] [03] [9A] [01] [0C] [00] [A3] [5D]

response: [FF] [00] [9A] [00] [00]

sendCommand: [FF] [10] [2F] [00] [00] [01] [22] [00] [00] [05] [07] [22] [10] [00] [1B] [03] [E8] [01] [FF] [DD] [2B]

response: [FF] [04] [2F] [00] [00] [01] [22] [00] [00]

response: [FF] [00] [22] [04] [00]

Scanning

response: [FF] [00] [22] [04] [00]

Scanning

response: [FF] [00] [22] [04] [00]

Scanning

response: [FF] [00] [22] [04] [00]

last three lines are repeated continuously even if the tags touch the antenna

It shows such a response with or without tags near the antenna… What do you think?

Best regards,

Eduard

7

this indeed shows that no tag is detected. The commands that have been are accepted without error codes.

8

Can you provide a photo of the U.FL SMD connector on the board without a connector attached?

I am wondering if perhaps the U.FL antenna connector may have been installed improperly. It does have specific polarities on the solder connections.

It might be hard to see in the photo, but it might be identifiable.

9

Also, there should see continuity between these two points, if you don’t find continuity here you may have either not set the jumpers correctly, or we installed the u.fl connector on backwards.

Let us know what you find.

Continuity RFID reader.png
Continuity RFID reader.png500×560 79.1 KB

10

Thank you for your comments!

Please see the attached file with photos representing the connection. Could you instruct me further what else I can try in order to establish the RFID tag reading?

Many thanks!

Best regards,

Eduard

RFID reader connection.pdf (553 KB)

11

all looks how it should be. If you have an ohm meter, connect one pin to the blob of solder connection and the other to the antenna internal wire. is that a full (zero resistance) connection ?

12

Thank you for your question!

It has 0.3 ohms.

Once the RIFD reader shielded to Arduino is powered by the PC’s USB/ wall adapter, I can read 0.25 (+/- 0.01) V being supplied onto the antennas connector and cable.

Cheers,

Eduard

13

Is there an option to check the antenna? E.g. an ohmmeter doesn’t show any values between the contacts of the antenna.

14

I would expect no measurement on the antenna itself… but if the cable is not well fitted to the antenna, it will not work. Did you get a replacement one already?

15

I’ve got a new antenna (https://www.sparkfun.com/products/14131) but still no response from the reader (https://www.sparkfun.com/products/14066) to indicate any RFID tags (https://www.sparkfun.com/products/16464). I’ve reactivated the reader’s PCB antenna, it functions normally with these tiny RFID tags.

Is it possible that this antenna doesn’t read Murata RFID Tags 865-928MHZ?

I am running out of options…

Best wishes,

Eduard

16

Because the tags are so small they need an antenna that concentrates it’s signal into a small space. The antenna below should work with the rain tags.

https://www.sparkfun.com/products/15113

17

SOLVED!

The proposed antenna UHF RFID Antenna (RP-TNC) WRL-14131 is not applicable for reading Ultra-Small UHF RFID Tag Rain 16464. Its polarization is linear whereas these tags require circular.

I don’t understand why the engineer consultants from Digi-key and Sparkfun told me that UHF RFID Antenna (RP-TNC) WRL-14131 will read ultra-small Murata tags.

SOLUTION I have tried RFID Antenna 902MHz ~ 928MHz (Murata Electronics RFID UHF LOOP ANTENNA), it functions normally. However, the reading range between the tag and antenna’s ring is only up to 3 mm.