Using AAT on NFC08a1

[CT-55555]

Hello everyone,
I am using an NFC08A1 for my project and I would like to use the AAT. I roughly understand what happens in the AAT algorithm. However, I don't get any noticeable improvement when I apply it. The range in particular remains almost the same.

An external antenna is used in the project and I would like to achieve optimum performance. Which default values do I have to change in the algorithm to achieve this? And when does it make sense to call the AAT? Later I want to switch between two readers. Is it necessery to call the function everytime I change the reader or is it possible to store the best configuration. 

Rgds

[Ulysses HERNIOSUS · Accepted solution]

Hi,

two remarks here:

1. Did you disable the setting of AAT registers from analog config? Per default these are overwriting any tuned values....
2. On a well tuned board like the NFC08 without a strong detuning element there is likely not much of an effect. You can try to put a metal plate close and then you may see a difference of re-tuned vs un-tuned antenna. But don't expect a boost of multiple centimeters!

BR, Ulysses

[CT-55555]

Hi,

1. Did you mean this part of the rfal_analogConfigTbl.h: 

if not please let me know. 

2. I connected a external Antenna to the board using normal wires. The distance between the antenna and the board is now about 100 cm. I also placed different metall objects near the antenna. I think these are strong detuning elements. 

Rgds 

[Ulysses HERNIOSUS]

Hi,

ad 1) Yes, it is about these registers. Critical for you is not the setting in CHIP_INIT but the other settings in POLL_COMMON and LISTEN_*. I think in the GUI we are providing analog configs for playing with the AAT (which don't have these settings) - also mentioned in the AAT appnote.

ad 2. Are you having 1m in differential mode. Not sure how well this can work. Maybe @Travis Palmer can comment on this.

BR, Ulysses

[CT-55555]

Hi, 

ad 1) I am not really sure what you mean. I am using the function st25r3916AatTune(NULL,NULL) with the default values. I also checked the Pins AAT_A and AAT_B and the voltage is changing. I assume the function tries to figure the best option. Is this correct ? 

ad 2) Yes, I am using the antenna in differential mode and i can read and write blocks from the Tag. 

Rgds

[Ulysses HERNIOSUS]

Hi,

ad 1) please see AN5322 chapters 8.3/8.4. It should make it clear what I mean.

Best Regards, Ulysses

[CT-55555]

Hi, 

I watched the chapter 8.3 on the AN5322 but I did not get it. Did you mean that if you use the AAT and don't disable the AAT registers on analog config. The algorithm starts overwriting the tuned values and an improvement is not noticeable? 

Rgds 

[Ulysses HERNIOSUS]

Yes.

I think I mixed chapters. Should have been 8.2(Analog Configuration) and 8.3(Polling tab).

[Roger SHIVELY]

Hello @CT-55555 ,

There has been a case created to resolve this question and we will be reaching out to you directly.

Regards,
Roger