NFC tag ATQA&SAK

Question

Hi， 
 Using nfc tag function，Need tag custom reply ATQA /SAK, Is this operation supported？ 
 
 ISO14443-3.pdf

SwRa · Accepted Answer

Hi Sean, 
 Need tag custom reply ATQA /SAK, Is this operation supported？ 
 Yes, it does support this operation. I checked with experts regarding this and here is a brief explanation on how to change it. The solution depends on the for the frame you needs to customize: 
 
 ATQA - use nfc_t4t_parameter_set() function to set the desired NFCID1 (UID); as of Bit Frame SDD, we don't provide an API to modify it, so you will need to set it directly in the nrfx_nfct.c driver source code: line 158 in function nrfx_nfct_hw_init_setup() : modify nrf_nfct_sensres_bit_frame_sdd_set(NRF_NFCT_SENSRES_BIT_FRAME_SDD_00100); You can change to a desired bit frame SDD value. Changing other bits in ATQA doesn't make sense - we shouldn't declare the Type 1 Tag support. 
 SAK - depends on which tag library is used:
 
 Type 2 Tag: set the desired SAK value using: nrfx_nfct_parameter_set() , call it before nfc_t4t_emulation_start() 
 Type 4 Tag: use nfc_t4t_parameter_set with NFC_T4T_PARAM_SELRES parameter, call it before nfc_t4t_emulation_start()

For the NFCT driver APIs, see https://infocenter.nordicsemi.com/topic/sdk_nrf5_v17.1.0/group__nrf__nfct.html 
 For the T4T and T2T APIs, see https://infocenter.nordicsemi.com/topic/sdk_nrf5_v17.1.0/group__nfc__api.html 
 Regards, 
 Swathy

NFC tag ATQA&SAK

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