Copyright 2015, EM Microelectronic-Marin SA
4325-DS, Version 7.0, 24-Apr-15
www.emmicroelectronic.com
420005-A01, 2.0
Functional Description
The EM4325 is used in passive, or battery assisted passive (BAP), UHF read-only or read/write transponder applications
operating at 860 MHz - 960 MHz. It is powered either by a battery or by the RF energy transmitted by the reader, which is
received and rectified to generate a supply voltage for the device.
The device is normally off if it is used in a passive application and normally ready to receive commands if used in a BAP
application. Once the device completes its power-on reset (POR), a Boot Sequence is performed that loads configuration data
and other commonly used information from EEPROM into registers and then transitions the device into either a Tag Only
Talks After Listening (TOTAL) protocol or into a Reader Talk First (RTF) protocol.
In the TOTAL protocol, the devices listens for a short period of time to determine if a reader is attempting to use the RTF
protocol. If the RTF protocol is not detected then the device assumes the reader is waiting for an automated response and will
initiate communications. The device continues to listen for the reader to use the RTF protocol and will automatically switch to
RTF protocol if it is detected and then switch back to TOTAL protocol when the RTF communications are completed.
In the RTF protocol, the reader initiates communications to the device and the device provides a response to the reader only
when appropriate. Additional custom commands/responses are implemented in this device to support SPI operation and
temperature readings. RTF protocol supports read/write EEPROM operations.
The device includes a programmable auxiliary function that can be used to support:
- Tamper detection feature that checks impedance of a continuity loop. Tamper detection can be implemented using a simple
continuity loop, with heat sensitive fuse wire, with sensors having both high and low impedance states, or with external
devices controlling an electronic switch such as a MOSFET.
- Notification of an RF event to external devices. RF events that are available for output are the detection of an RF field, the
detection of Gen2/6C commands, the detection that the device has been singulated, or the present state of the Select flag.
A programmable 4-bit I/O port can be configured to provide four general purpose I/O signals or an SPI bus. The SPI bus
allows communications to/from an SPI device on a tag and allows for control and data exchange between a reader and other
components on a tag. The device uses the configuration data to determine if it is an SPI Master or an SPI Slave device.
An integrated temperature sensor provides an absolute temperature reading on demand. BAP applications can be
programmed to set temperature alarm conditions, provide continuous temperature monitoring, and provide the time stamp for
when an alarm condition occurs.
This device is in full compliance with ISO/IEC 18000-63, ISO/IEC 18000-64, EPC
TM
Class-1 Generation-2, AIAG
TM
B-11, and
ATA Spec 2000 Chapter 9 Low Memory Tag Model specifications according to the following documents:
"ISO/IEC 18000-63 Information technology – Radio frequency identification for item management – Part 63:
Parameters for air interface communications at 860 MHz to 960 MHz Type C”
"ISO/IEC 18000-64 Information technology – Radio frequency identification for item management – Part 64:
Parameters for air interface communications at 860 MHz to 960 MHz Type D”
"EPC Radio-Frequency Identity Protocols, Class-1 Generation-2 UHF RFID, Protocol for Communications at
860 Mhz - 960 MHz, Version 1.2.0” from EPCglobal Inc.
"EPCglobal Tag Data Standards, Version 1.8" from EPCglobal Inc.
“B-11, Item Level Radio Frequency Identification (RFID) Standard”, Revision 8, from Automotive Industry Action
Group
“ATA Spec 2000 Chapter 9, Automated Identification and Data Capture (AIDC)”, from Air Transport Association
The ISO/IEC 18000-63, ISO/IEC 18000-64, and the EPC
TM
Class-1 Generation-2 specifications have many optional features
and the following table identifies which of them are supported by this device.