Automatic antenna tuning (AAT) technique on NFC06A1

[TZhou.2]

Hi, I want to reconfigure the TX Power from transmitter to receiver. How to adjust my code to control automatic antenna tuning (AAT)? For example, I can increase the TVDD to max value which is the power supply of the tx driver, and which part of the programming code needs to be defined? Thanks,

[Ulysses HERNIOSUS]

Hi TZhou.2,

I think most of it is already answered in this thread here: energy-efficiency-on-nfc06a1-board. There we discussed some detail about the AAT.

AAT is not meant to reconfigure the TX power but rather meant for changing the type of matching to compensate detuning, etc.

For changing the transmit power you can look into d_res (part of analogConfigTbl_NFC06A1.c) and also the regulator may be an option at times (reg_s and rege which you could put into analogConfigTbl; or even use a bypass according to Datasheet). Playing with the regulator, please make sure to stay within physical limits of the chip and also watch out as it may affect noise resistance).

Best Regards, Ulysses

[TZhou.2]

Hi Ulysses,

Thanks for your information. I checked d_res code (this line: 0x0028,0x0f,0x00, /* RFO driver resistance Active transmission (d_res); Set RFO resistance Active Tx */), and I want to study more about how to re-define these res values to configure TX power? Could you give me a more detailed answer to this? Thanks

[Ulysses HERNIOSUS]

Hi TZhou.2,

not sure what you are trying to achieve.....

If you want to adapt/lower the output power statically then you can just adapt that line in analog configs.

If you want to adapt the driver resistance during runtime then use st25r3916ModifyRegister(ST25R3916_REG_TX_DRIVER, ST25R3916_REG_TX_DRIVER_d_res_mask, ...) whenever you feel like it.

BR, Ulysses

[TZhou.2]

Hi Ulysses, thanks for your fast reply. I want to adapt/lower the output power of antenna, but not sure how to adapt these reg numbers. Could you provide coding examples for this? For example, if I want to amplify the output power, three value (0x0028,0x0f,0x00) should changed to what? I am not familiar with reg coding, and thanks for your help.

[Ulysses HERNIOSUS]

Hi,

please see Table 78 RFO driver resistance of the DS. The number in the table will need to be multiplied with RRFO (Table 123). The three values in the table are Register-Mask-Value: Register 0x28, Mask 0x0f (d_res), Value (d_res).

E.g.

• (0x0028,0x0f,0x00) -> 1.0 * 1.7ohm = 1.7ohm is already the maximum
• ..
• (0x0028,0x0f,0x2) -> 4.1 * 1.7ohm = 6.97ohm
• ...

Best Regards, Ulysses