apple’s 2011/0221575 application and RFID memory
Published United States Patent Application 2011/0221575 (‘575) came to light last week catching the attention of Appleinsider. The timing of such publications is often an interesting coincidence, with ‘575 appearing just as rumours say iPhone 5 is about to arrive. Will iPhone 5 have RFID capabilities? It is certainly too big a leap to think […]
Published United States Patent Application 2011/0221575 (‘575) came to light last week catching the attention of Appleinsider. The timing of such publications is often an interesting coincidence, with ‘575 appearing just as rumours say iPhone 5 is about to arrive. Will iPhone 5 have RFID capabilities? It is certainly too big a leap to think the iPhone 5 will sport RFID capabilities because of this application. However, there were some interesting hardware considerations in the various embodiments discussed in ‘575.
In broad brush strokes ‘575 presents systems and methods for providing messages related to the operation or failure of an electronic device, even after the device has failed. These messages may include error messages and messages related to the operation of software on the device. RFID circuitry is well suited to this use as it can be independently powered by the RF reader allowing information be extracted from the RFID memory, even after the rest of the device, including the power supply, has failed.
Embodiments of an RFID system are outlined in Fig. 3 and Fig. 4, and discussed in paragraphs  to , and  to , respectively. In both embodiments specific error messages are stored in separate pre-programmed memories, with the system in Fig.4 having a higher granularity. In both of these embodiments a particular error message is stored in a particular memory. The desired error message is selected when the control circuit selects the memory. In paragraph : “Such high speed communication may be desirable in situations where device 300 is about to completely fail and the error message in second memory 316 needs to be selected before failure”. In other words, one can provide the desired error message without having to write the message to memory in the limited time in a failure situation.
Why might such a system be advantageous? The outlined RFID circuit operates like a kind of tag that is in this case connected to and communicates with the circuitry of the electronic device. Now the memory of a tag is commonly EEPROM, which is non-volatile and cheap. This works well in situations where one simply wants to read data from the tag. However EEPROM has very slow writes and has a limited write endurance. In the case of a device failure there may not be sufficient time to write the error message to EEPROM. Thus one would want a way around this slow write speed.
So what about the embodiment presented in Fig. 5? It contains rewritable memory 512. In paragraph : “… memory 512 may store information written thereto by control circuit 520”. Other comments about memory 512 include “ … may store any information suitable for being provided as a message by RFID circuit 510…”, “… memory 512 may store error messages and various software events…”, and in paragraph  “… memory 512 of RFID circuitry 510 provides limitless opportunity to communicate messages of varying specificity…” and “Other information such as the software event information may be updated at predetermined time intervals by writing updated data to memory 512 …”. This sure does not sound like performance requirements EEPROM could meet. Is it possible for another type of memory to meet the described performance? FRAM comes to mind.
‘575 does not mention many of the hardware details, including the nature of the RFID memory associated with the various embodiments. It appears to be directed more towards implementations of RFID circuits and their uses. However, if the rewritable memory 512 still has to meet the requirement of writing an error message prior to device failure it is probably advisable to be a memory other than EEPROM. Else, it has to be a really short message.