Datasheet

Product data sheet

COMPANY PROPRIETARY

Rev. 3.0 — 17 October 2011

213830 15 of 30

NXP Semiconductors

NTAG203

NFC Forum Type 2 Tag compliant IC with 144 bytes user memory

8.6 Counter

NTAG203 features 16-bit one-way counter, located at first two bytes of page 29h. In its

delivery state, counter value is set to 0000h.

The first

valid Write or Compatibility write to the address 29h can be performed with any

value in the range between 0001h and FFFFh and corresponds to initial counter value.

Every consequent valid WRITE command, which represents the increment, can contain

values between 0001h and 000Fh. Upon such WRITE command and following mandatory

RF reset, the value written to the address 29h is added to the counter content.

If - after initial write - a value higher then 000Fh is used as a parameter, NTAG203 will

answer with NAK. Once counter value reaches FFFFh and an increment is performed via

valid command, NTAG203 will answer with NAK. If the sum of counter value and

increment is higher than FFFFh, NTAG203 will answer with NAK and will not update the

counter.

Increment by zero (00h) is always possible, but does not have any impact to counter

value.

8.7 PICC response to a command from NFC device

NFC Tag Type 2 compliant IC uses, apart from the responses defined in the following

sections, two half-byte answers to acknowledge the command received in Active state

(see Figure 4 “

Communication principle state diagram - 4-byte; 16-byte”).

NFC Tag Type 2 compliant IC distinguishes between positive (ACK) and negative (NAK)

acknowledge. Valid values for ACK and NAK are shown in Table 8 “

ACK and NAK

values”.

After every NAK, NTAG203 will perform an internal reset.

1. First valid write is defined as write to a counter value of zero with an argument different then zero

Table 8. ACK and NAK values

Answer value Answer explanation

Ah positive acknowledge (ACK)

1h parity or CRC error (NAK)

0h any other error (NAK)