How fast is the pass-through mode via I2C to RF?

[xnormanw]

Dear NXP-Team,

I'm currently trying out the pass-through mode. But somehow, I can't reach any faster speeds than almos 1.2 kb/s. Is there a way to achieven more and if yes - how? I'm using an Arduino Uno and my own wirtten Android App with Huawei, which basically only "fast_read"s the SRAM and checks the NS_REG if data is available.

Kind regards

Norman

[xnormanw]

Hi Ricardo,

Thanks for your answer, 30 kbps sounds amazing! Do you have any tips or advices how to reach those numbers, e.g. how to program the app/mcu? Currently my phone requires approx. 22 ms to fast_read the sram. After that, it checks the NS_REG for the RF_READY_BIT till it can read again.

Kind regards,

Norman

[nxf58474]

Hi Norman,

From the Host side, it is recommended to use FD pin to synchronize the data transfer.

Only in case FD pin cannot be used as interrupt, polling RF_LOCKED bit needs to be used.

The performance will depend of all the system, and every system is different, that’s why we can't recommend something more specific to your system.

Regards,

Ricardo

[xnormanw]

Hi Ricardo,

thank you for your great replay. I tried to use the FD_PIN as an interrupt on my arduino uno, but before I tried to read the different states of the FD_PIN. The FD_PIN is connected with Port 8 of my arduino uno. After initializing the pin with

 pinMode(fd_pin, INPUT_PULLUP);, I try to read its states while using the pass-through mode, but its values always stay 0. Also the session and configuration register bits for FD_ON and FD_OFF are both set on 11b.

Is there something I'm missing?

Kind regards

Norman

[nxf58474]

Hi Norman,

In sections 11.3.2 and 11.3.3 of the Data Sheet are some illustrations of the FD behavior when the pass-through mode is enabled. In case of NFC->I2C communication, the NC_REG value is 7Dh (PTHRU_ON_OFF = 1, FD_OFF = 1, FD_ON = 1, TRANSFER_DIR = 1).

In case of I2C->NFC the NC_REG value is 7Ch (PTHRU_ON_OFF = 1, FD_OFF = 1, FD_ON = 1, TRANSFER_DIR = 0).

I cannot help you from your MCU side, but this is the configuration needed for the FD pin.

Regards,

Ricardo

[nxf58474]

Hi Norman,

Hope you are doing well. With an optimized closed system, pass through data rate of approximately 40 kbps can be achieved there are some mobile phones that might get the 30 kbps.

Unfortunately that limitation could come from the I2C of your MCU, or from the Phone you are using, or even both. The NFC Reader (Phone) would be the master in the communication. Overall throughput heavily depends on NFC reader middleware/firmware/OS implementation within the specific hardware

Best Regards,

Ricardo