The NFCT peripheral contains a 13.56 MHz AM receiver and a 13.56 MHz load modulator with 106 kbps data rate as defined by the NFC Forum.
When transmitting, the frame data will be transferred directly from RAM and transmitted with configurable frame type and delay timing. The system will be notified by an event whenever a complete frame is received or sent. The received frames will be automatically disassembled and the data part of the frame transferred to RAM.
The NFCT peripheral also supports the collision detection and resolution ("anticollision") as defined by the NFC Forum.
Wake-on-field is supported in SENSE mode while the device is either in System OFF or System ON mode. When the antenna enters an NFC field, an event will be triggered notifying the system to activate the NFCT functionality for incoming frames. In System ON, if the energy detected at the antenna increases beyond a threshold value, the module will generate a FIELDDETECTED event. When the strength of the field no longer supports NFC communication, the module will generate a FIELDLOST event. For the Low Power Field Detect threshold values, refer to NFCT Electrical Specification.
In System OFF, the NFCT Low Power Field Detect function can wake the system up through a reset. See RESETREAS for more information on how to detect a wakeup from NFCT.
If the system is put into System OFF mode while a field is already present, the NFCT Low Power Field Detect function will wake the system up right away and generate a reset.
The HFXO must be running before the NFCT peripheral goes into ACTIVATED state. Note that the NFCT peripheral calibration is automatically done on ACTIVATE task. The HFXO can be turned off when the NFCT peripheral goes into SENSE mode. The shortcut FIELDDETECTED_ACTIVATE can be used when the HFXO is already running while in SENSE mode.
Outgoing data will be collected from RAM with the EasyDMA function and assembled according to the TXD.FRAMECONFIG register. Incoming data will be disassembled according to the RXD.FRAMECONFIG register and the data section in the frame will be written to RAM via the EasyDMA function.
The NFCT peripheral includes a frame timing controller that can be used to accurately control the inter-frame delay between the incoming frame and a corresponding outgoing frame. It also includes optional CRC functionality.