SL3ICS1002 datasheet(36/56 Pages) NXP

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139036

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Product data sheet

COMPANY PUBLIC

Rev. 3.6 — 10 March 2011

139036

36 of 56

NXP Semiconductors

SL3ICS1002/1202

UCODE G2XM and G2XL

15.12 Custom Commands

15.12.1 ReadProtect

The G2X ReadProtect custom command enables reliable read protection of the entire

G2X memory. Executing ReadProtect from the Secured state will set the ReadProtect-bit

to '1'. With the ReadProtect-Bit set the G2X will continue to work unaffected but fail its

content.

Following commands will be disabled: Read, Write, Kill, Lock, Access, ReadProtect,

ChangeEAS, EAS Alarm and Calibrate. The G2X will only react upon an anticollision with

Select, Query, QueryRep, QueryAdjust, ACK (no truncated reply), NAK, ReqRN but reply

with zeros as EPC and CRC-16 content (except PC/password). ACK will return zeros

except for the PC.

The read protection can be removed by executing Reset ReadProtect. The

ReadProtect-Bit will than be cleared.

Devices whose access password is zero will ignore the command. A frame-sync must be

prepended the command.

After sending the ReadProtect command an interrogator shall transmit CW for the lesser

of TReply or 20 ms, where TReply is the time between the interrogator's ReadProtect

command and the backscattered reply. An interrogator may observe three possible

responses after sending a ReadProtect, depending on the success or failure of the

operation:

• ReadProtect succeeds: After completing the ReadProtect the G2X shall backscatter

the reply shown in Table 19 comprising a header (a 0-bit), the tag's handle, and a

CRC-16 calculated over the 0-bit and handle. Immediately after this reply the G2X will

render itself to this ReadProtect mode. If the interrogator observes this reply within 20

ms then the ReadProtect completed successfully.

• The G2X encounters an error: The G2X will backscatter an error code during the CW

period rather than the reply shown in the EPCglobal Spec (see Annex I for error-code

definitions and for the reply format).

• ReadProtect does not succeed: If the interrogator does not observe a reply within

20 ms then the ReadProtect did not complete successfully. The interrogator may

issue a Req_RN command (containing the handle) to verify that the G2X is still in the

interrogation zone, and may re-initiate the ReadProtect command.

The G2X reply to the ReadProtect command will use the extended preamble shown in

EPCglobal Spec (Figure 6.11 or Figure 6.15), as appropriate (i.e. a Tag shall reply as if

TRext=1) regardless of the TRext value in the Query that initiated the round.

Table 17.

ReadProtect command

Command

CRC-16

# of bits

description

11100000 00000001

handle

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