AT24RF08 - Revision history

Lambda.tango: AT24RF08C: Replaced broken datasheet link with DigiKey copy and removed broken (doesn't seem to exist anymore) product page link. AT24C08: Updated broken product page link and updated working datasheet link (to match Atmel site structure).

2013-10-10T23:00:25Z

AT24RF08C: Replaced broken datasheet link with DigiKey copy and removed broken (doesn't seem to exist anymore) product page link. AT24C08: Updated broken product page link and updated working datasheet link (to match Atmel site structure).

Hmh: Reword paragraph so that it makes sense in english

2007-01-18T01:53:20Z

Reword paragraph so that it makes sense in english

Marvin at 08:42, 6 February 2006

2006-02-06T08:42:58Z

Wyrfel at 23:12, 17 January 2006

2006-01-17T23:12:58Z

Wyrfel at 23:12, 17 January 2006

2006-01-17T23:12:30Z

Hmh: Fix wikilink to Maintenance#Recovering_BIOS_passwords

2005-12-01T12:15:43Z

Fix wikilink to Maintenance#Recovering_BIOS_passwords

Hmh: Initial submission

2005-12-01T12:14:11Z

Initial submission

New page

The ATMEL AT24RF08 (24RF08 for shorts) is a 8KiB serial access EEPROM with an RFID interface. Its serial interface is similar to that of the AT24C08 EEPROM, and it is better described in the AT24C08 datasheet.

Serial interface access to the EEPROM is available through the I2C bus on some ThinkPads, at I2C addresses 0x54 - 0x57 with an additional "access protection page" at address 0x5c. Since the chip itself is not an I2C client, a bridge of some sort is likely being employed. This is probably the reason for the [[Problem_with_lm-sensors|Problem with lm-sensors killing some older ThinkPads]].

The RF interface is not used on the ThinkPads, but the EEPROM also has a memory protection map, which the BIOS uses to protect access to sensitive data. Note that this means the EEPROM suffers at least two write cycles every boot (unprotect/protect).

ThinkPads store critical information on this EEPROM, including the BIOS admin password. Editing this EEPROM bypassing the BIOS requires hardware hacking to access the chip's serial interace directly, however. It also requires special programs to access the chip's serial interface and decode the password. The procedure is detailed in [[http://www.thinkwiki.org/wiki/Maintenance#Recovering_BIOS_passwords]].

===External Sources===
* [http://www.atmel.com ATMEL]
* [http://www.atmel.com/dyn/resources/prod_documents/DOC1072.PDF ATMEL - Direct link to AT24RF08C datasheet]
* [http://www.atmel.com/dyn/resources/prod_documents/doc3256.pdf ATMEL - Direct link to AT24C08 datasheet]
* [http://www.atmel.com/dyn/products/product_card.asp?family_id=644&family_name=RF+Identification&part_id=2370 ATMEL - AT24RF08C product page]
* [http://www.atmel.com/dyn/products/product_card.asp?family_id=647&family_name=Serial+EEPROM&part_id=3701 ATMEL - AT24C08 product page]

@@ Line 5: / Line 5: @@
 An important difference to the 24C08 is, that burst writes over page boundaries WRAP AROUND to the beginning of the same page, instead of continuing in the next page.
-Older Thinkpads suffered from accidental writes to this EEPROM by the device discovery routines in old lm_sensors implementations [[Problem_with_lm-sensors|Problem with lm-sensors killing some older ThinkPads]], resulting in a corrupted CMOS checksum ("CRC2 Error").
+Older Thinkpads suffered from accidental writes to this EEPROM by the device discovery routines in old lm_sensors implementations, resulting in a corrupted CMOS checksum ("CRC2 Error") as described in the [[Problem with lm-sensors|problem with lm-sensors page]].
 The RF interface is not used on the ThinkPads, but the EEPROM also has a memory protection map, which the BIOS uses to verify the existence of the 24RF08 Part (otherwise it could be replaced with the 24C08 part). Note that this means the EEPROM suffers at least two write cycles every boot (unprotect/protect).

@@ Line 6: / Line 6: @@
 ThinkPads store critical information on this EEPROM, including the BIOS admin password.  Editing this EEPROM bypassing the BIOS requires hardware hacking to access the chip's serial interace directly, however.  It also requires special programs to access the chip's serial interface and decode the password.  The procedure is detailed in [[Maintenance#Recovering_BIOS_passwords|Recovering BIOS Passwords]].
 == ThinkPads this chip may be found in ==
 *ThinkPad {{570E}}
 *ThinkPad {{600E}}, {{600X}}
@@ Line 22: / Line 14: @@
 *ThinkPad {{X20}}
 *probably more

@@ Line 21: / Line 21: @@
 ==External Sources==
 * [http://www.atmel.com ATMEL]
-* [http://www.atmel.com/dyn/resources/prod_documents/DOC1072.PDF ATMEL - Direct link to AT24RF08C datasheet]
+* [http://media.digikey.com/pdf/Data%20Sheets/Atmel%20PDFs/AT24RF08C.pdf DigiKey - AT24RF08C datasheet on DigiKey]
 * [http://www.atmel.com/dyn/resources/prod_documents/doc3256.pdf ATMEL - Direct link to AT24C08 datasheet]
-* [http://www.atmel.com/dyn/products/product_card.asp?family_id=644&family_name=RF+Identification&part_id=2370 ATMEL - AT24RF08C product page]
+* [http://www.atmel.com/devices/at24c08.aspx ATMEL - AT24C08 product page]

@@ Line 1: / Line 1: @@
 The ATMEL AT24RF08 (24RF08 for shorts) is a 8KiB serial access EEPROM with an RFID interface.  Its serial interface is similar to that of the AT24C08 EEPROM, and it is better described in the AT24C08 datasheet.
-Serial interface access to the EEPROM is available through the I2C bus on some ThinkPads, at I2C addresses 0x54 - 0x57 with an additional "access protection page" at address 0x5c.  Since the chip itself is not an I2C client, a bridge of some sort is likely being employed.  This is probably the reason for the [[Problem_with_lm-sensors|Problem with lm-sensors killing some older ThinkPads]].
+Serial interface access to the EEPROM is available through the I2C bus on some ThinkPads, at I2C addresses 0x54 - 0x57 with an additional "access protection page" at address 0x5c.
-The RF interface is not used on the ThinkPads, but the EEPROM also has a memory protection map, which the BIOS uses to protect access to sensitive data. Note that this means the EEPROM suffers at least two write cycles every boot (unprotect/protect).
+An important difference to the 24C08 is, that burst writes over page boundaries WRAP AROUND to the beginning of the same page, instead of continuing in the next page.
 ThinkPads store critical information on this EEPROM, including the BIOS admin password.  Editing this EEPROM bypassing the BIOS requires hardware hacking to access the chip's serial interace directly, however.  It also requires special programs to access the chip's serial interface and decode the password.  The procedure is detailed in [[Maintenance#Recovering_BIOS_passwords|Recovering BIOS Passwords]].