Rev. 1.00
180
September 11, 2018
Rev. 1.00
181
September 11, 2018
HT45F4050
A/D NFC Flash MCU
HT45F4050
A/D NFC Flash MCU
The response of the selected NFC tag device to the Select CL2 command is the Select Acknowledge
(SAK) byte, which in accordance with ISO/IEC 14443 indicates that the anticollision cascade
procedure has finished. After this the selected NFC tag device is now uniquely selected and only this
device will communicate with the NFC polling device even if other contactless devices are present
within the NFC field.
ACTIVE State
When a NFC tag device in the READY1 or READY2 state is read from page 0x00h~0x0Fh by a
READ command or successfully selected by a Select CL2 command in the READY2 state, it will
enter the ACTIVE state. All memory related operations, read or write, are executed in the ACTIVE
state. The available commands in the ACTIVE state include the READ, FAST_READ, WRITE,
COMPATIBILITY_WRITE and GET_VERSION commands. When an available command is
received but is followed by a NAK signal in reply, the device will exit the ACTIVE state and enter
the IDLE or HALT state according to its previous state. The NFC tag device will exit the ACTIVE
state and switch to the HALT state when a HLTA command is received and executed successfully.
However, the device will enter the IDLE state when a
n
HLTA command is received and a NAK
signal is sent in reply if the device has never entered the HALT state. Any other command received
in this state is interpreted as an error and the NFC tag device will return to the IDLE or HALT state
depending on its previous state.
HALT State
When a halt command, HLTA, is successfully executed in the ACTIVE state, the NFC tag will enter
the HALT state. The only way to exit the HALT state is with the execution of the WUPA command.
Any other command received in the HALT state will be interpreted as an error and the NFC tag
device will stay in the HALT state. A
n
NFC tag device with a recognized UID can be set in the
HALT state. To execute the anticollision process the NFC reader can transmit a REQA command
followed by an Anticollision command to simply distinguish between the recognized tag devices and
the devices whose UID bytes are necessary to be resolved.
NFC Command Set
The device NFC function follows the ISO/IEC 14443 Type A standard. The NFC function is also
compatible with the NFC Forum Type 2.
After the NFC tag device has been selected, it can be
activated or deactivated using various commands. All available commands for the NFC function are
shown in the table below.
Command
ISO/IEC 14443 Type A
NFC Forum Type 2
Command Code
REQA
REQA
SENS_REQ
26h (7-bit)
WUPA
WUPA
ALL_REQ
52h (7-bit)
Anticollision CL1
Anticollision CL1
SDD_REQ CL1
93h 20h
Select CL1
Select CL1
SEL_REQ CL1
93h 70h
Anticollision CL2
Anticollision CL2
SDD_REQ CL2
95h 20h
Select CL2
Select CL2
SEL_REQ CL2
95h 70h
HLTA
HLTA
SLP_REQ
50h 00h
READ
—
READ
30h
GET_VERSION
—
—
60h
FAST_READ
—
—
3Ah
WRITE
—
WRITE
A2h
COMPATIBILITY_WRITE
—
—
A0h
To ensure reliable data transfer the data integrity mechanisms including the CRC, Block Check
Character and parity bytes are provided in the NFC tag device. Refer to the following command
description for details.