RE: How can i change NFC T4T library timeout variable

alireza sadeghpour — Fri, 18 Jan 2019 14:19:09 GMT

Hi and thanks for your response,

i had set the FWI as you advised but it dose not has any impact on the nfc stack behaviour and again i receive 0x63 0x00 after 200ms in computer side. i am beginner in NFC and i want to know that this is standard behaviour? and there is any other option that i can try to solve the problem??

RE: How can i change NFC T4T library timeout variable

tesc — Mon, 14 Jan 2019 16:09:26 GMT

Hi,

We do not have an example.

The FWI value is of type uint8_t, has a default value of 4, and a maximum value of either 4 or 7 depending on the SoC. Trying to set a too high value will give NRF_ERROR_INVALID_PARAM. You can see how FWI is converted to period here:

#define NFC_T4T_FWI_TO_FWT(FWI)      (256u * 16u * (1 << (FWI)))                /**< Macro for calculating FWT (in number of NFC carrier periods) from FWI parameter. */

I.e. the period will double for each FWI increment of one, and it will halve for each decrement of one. By that logic, a value of 6 would give 800 ms (if a value of 4 gives 200 ms).

That means you should do something along the lines of:

uint8_t new_FWI = 6;
ret_code_t err_code = nfc_t4t_parameter_set(NFC_T4T_PARAM_FWI, (void *) &new_FWI, sizeof(new_FWI));
app_error_check(err_code);

Regards,
Terje