SL3S1003_1013 All information provided in this document is subject to legal disclaimers. © NXP Semiconductors N.V. 2015. All rights reserved.
Product data sheet
COMPANY PUBLIC
Rev. 3.7 — 21 May 2015
201237 25 of 43
NXP Semiconductors
SL3S1003_1013
UCODE G2iM and G2iM+
10.7.5 ReadProtect
2
The UCODE G2iM ReadProtect custom command enables reliable read protection of the
entire UCODE G2iM memory. Executing ReadProtect from the Secured state will set the
ProtectEPC and ProtectTID bits of the Configuration Word to '1'. With the ReadProtect-Bit
set the UCODE G2iM will continue to work unaffected but veil its protected content.
The read protection can be removed by executing Reset ReadProtect. The
ReadProtect-Bits will than be cleared.
Devices whose access password is zero will ignore the command. A frame-sync must be
pre-pended the command.
After sending the ReadProtect command an interrogator shall transmit CW for the lesser
of T
Reply
or 20 ms, where T
Reply
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 UCODE G2iM shall
backscatter the reply shown in Table 23
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 UCODE G2iM will render itself to this ReadProtect mode. If the interrogator
observes this reply within 20 ms then the ReadProtect completed successfully.
• The UCODE G2iM encounters an error: The UCODE G2iM 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 UCODE G2iM is
still in the interrogation zone, and may re-initiate the ReadProtect command.
The UCODE G2iM 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.
2. Note: The ChangeConfig command can be used instead of “ReadProtect”, “ResetReadProtect”, “ChangeEAS”.
Table 22. ReadProtect command
Command RN CRC-16
# of bits 16 16 16
description 11100000 00000001 handle -
Table 23. UCODE G2iM reply to a successful ReadProtect procedure
Header RN CRC-16
# of bits 1 16 16
description 0 handle -
