139037 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2013. All rights reserved.
Product data sheet
COMPANY PUBLIC
Rev. 3.8 — 11 November 2013
139038 34 of 48
NXP Semiconductors
SL3ICS1002/1202
UCODE G2XM and G2XL
14.12.4 EAS_Alarm
EAS_Alarm is a custom command causing the G2X to immediately backscatter an
EAS-Alarmcode, when EAS ALARM bit is set without any delay caused by Select, Query
and without the need for a backend database.
The EAS feature of the G2X is available after enabling it by sending a ChangeEAS
command described in Section 14.12.3 “
ChangeEAS”. With an EAS-Alarm bit set to '1' the
G2X will reply to an EAS_Alarm command by backscattering a fixed 64 bit alarm code. A
G2X will reply to an EAS_Alarm command from the ready state only.
If the EAS-Alarm bit is reset ('0') by sending a ChangeEAS command in the password
protected Secure state the G2X will not reply to an EAS_Alarm command.
The EAS_Alarm command is structured as following:
• 16 bit command
• 16 bit inverted command
• DR (TRcal divide ratio) sets the T=>R link frequency as described in EPCglobal Spec.
6.3.1.2.8 and Table 6.9.
• M (cycles per symbol) sets the T=>R data rate and modulation format as shown in
EPCglobal Spec. Table 6.10.
• TRext chooses whether the T=>R preamble is prepended with a pilot tone as
described in EPCglobal Spec. 6.3.1.3.
A preamble must be prepended the EAS_Alarm command according EPCglobal Spec,
6.3.1.2.8.
Upon receiving an EAS_Alarm command the tag loads the CRC5 register with 01001b
and backscatters the 64 bit alarm code accordingly. The reader is now able to calculate
the CRC5 over the backscattered 64 bits received to verify the received code.
Table 21. EAS_Alarm command
Command Inv_Command DR M TRext CRC-16
# of bits 16 16 1 2 1 16
description 11100000
00000100
00011111
11111011
0: DR=8
1: DR=64/3
00: M=1
01: M=2
10: M=4
11: M=8
0: No pilot
tone
1: Use pilot
tone
-
Table 22. G2X reply to a successful EAS_Alarm command
Header EAS Code
# of bits 1 64
description 0 CRC5 (MSB)
