Receiver Gain of TRF7970A

Hello Hamada,

The hardware tuning will be essential for the NFC system to have consistent performance regarding range and sensitivity. A few questions on the hardware :

1. Which NFC mode you are using in the TRF7970A?

2. What hardware (TI hardware or designed PCB?) are you using to validate the NFC performance?

3. What range are you trying to achieve with NFC?

4. What are the antenna dimensions allowed for your application?

5. How are you testing the NFC system? (Free air, or inside an enclosure) The environment in which the system is tested in may affect the tuning of the antenna; therefore, affecting the NFC performance of the antenna.

For most of our customers they have are able to read / write tags without using the Receiver Gain Adjust direct command. Typcially we have seen cases where the tuning is correctly tuned (Q of 9) , and trying the different bandpass settings in the RX Special Setting Register (0x0A) has removed the protocol errors received when communicating with NFC enabled smartphones. Please see below the answer to your questions:

●Receiver Gain Adjust (0x1A)

(1)What kind of how to use does this command consider? This command should be used when you are reading a tag response and you are getting multiple protocol errors (for example in the case of ISO14443-A if you are reading holes, this is explained in Section 5 of the Firmware Design hints http://www.ti.com/lit/pdf/sloa159 ). In our code example we have been able to read tags (Type 2, 3, 4A/B, and 5) without using this command or the RX Special Register gain adjustment. The other case where this command is used is for cryptographic cards when they are too close to the reader, it may cause collision error detections due to noise.

(2)It includes following mentioning in 55 pages of data seat (SLOS743K).

　 This command ensures better operation in a noisy environment.

　 How can I judge that it's in the state of the "noisy environment"? A noisy enviroment is when you put the NFC transceiver in a system where tag is not replying to the polling command or when you are getting protocol errors when the tag is placed on the antenna.

(3)It's used by what kind of combination are two cashiers thinking? What do you mean "two cashiers thinking"?

Hope this helps!

Best Regards,

Erick

Hi, Erick.

Thank you for reply.

I answer a question.

>1. Which NFC mode you are using in the TRF7970A?
　No. It's being used in Card Emulation mode.

>2. What hardware (TI hardware or designed PCB?) are you using to validate the NFC performance?
When TRF7970AEVM was used, there were no defects of movement.

When a customer changes the hardware of TRF7970AEVM a little.
The following phenomenon occurred.


●When a tag of ISO15693 was read in ReadMultipleBlock.

　When I failed in Read in the state above-mentioned.
　Reading after next time becomes bad.


>3. What range are you trying to achieve with NFC?
It's within several centimeters.


>4. What are the antenna dimensions allowed for your application?
They're two dimensions.



>5. How are you testing the NFC system? (Free air, or inside an enclosure) The environment in which the system is tested in may affect the tuning of the antenna; therefore, affecting the NFC performance of the antenna.

It's in the usual state. (I think it isn't the noisy environment in particular.


Best Regards,

hamada

Hi, Erick.

>It's used by what kind of combination are two cashiers thinking? What do you mean "two cashiers thinking"?

I made a mistake. I'm sorry.
It's rewritten.


●Receiver Gain Adjust(0x1A), RX Special Register(0x0A)

(3)Is it assumed how to do combine and use 2 registers (0x1A/0x0A)?


Best Regards,

hamada