AN4125 Datasheet, PDF (1/15 Pages) STMicroelectronics – ST has published various supporting application

AN4125
Application note
How to manage simultaneous I²C and RF
data transfers with the M24LRxxE-R
Introduction
The M24LRxxE_R is an EEPROM device designed to be accessed via two different
interfaces: a wired I²C interface and a standard contactless ISO 15693 RFID interface.
Figure 1. Typical application of an M24LRxxE_R dual interface EEPROM
!PPLICATIONMASTER
3$!
3#,
)£#BUS
.-3YY&@3
)3/2&
!PPLICATIONBOARD
-36
ST has published various supporting application notes explaining how the RF interface
works and the basic principles of passive RFID technology. These documents are available
from: www.st.com/dualeeprom.
The possibility of using two different interfaces to control the dual-interface EEPROM implies
two host controllers: a microcontroller with an I²C bus and an ISO 15693 RFID reader. Due
to their nature, these two host controllers are not synchronized, which means that both
controllers might try to access the M24LRxxE_R concurrently.
To manage this kind of situation, the M24LRxxE_R has a built-in circuitry able to handle
possible concurrent communications and powering activities from the RF and I²C sides.
This application note describes how the M24LRxxE_R arbitration circuitry operates. It
applies to the products listed in Table 1.
Table 1.
Applicable products
Type
Part numbers
Memory products
M24LR04E-R, M24LR16E-R, M24LR64E-R
June 2012
Doc ID 023297 Rev 1
1/15
www.st.com