[U-Boot-Users] 512-Bytes EEPROM

VanBaren, Gerald (AGRE) Gerald.VanBaren at smiths-aerospace.com
Fri Apr 23 16:15:24 CEST 2004

Hi Bruno,

If you look in .../common/soft_i2c.c you will find the following:

	 * EEPROM chips that implement "address overflow" are ones
	 * like Catalyst 24WC04/08/16 which has 9/10/11 bits of
	 * address and the extra bits end up in the "chip address"
	 * bit slots. This makes a 24WC08 (1Kbyte) chip look like
	 * four 256 byte chips.
	 * Note that we consider the length of the address field to
	 * still be one byte because the extra address bits are
	 * hidden in the chip address.
	chip |= ((addr >> (alen * 8)) & CFG_I2C_EEPROM_ADDR_OVERFLOW);

	PRINTD("i2c_read: fix addr_overflow: chip %02X addr %02X\n",
		chip, addr);

The EEPROM you are using apparently uses the "overflow" method of addressing beyond the first 256 bytes.


> -----Original Message-----
> From: u-boot-users-admin at lists.sourceforge.net
> [mailto:u-boot-users-admin at lists.sourceforge.net]On Behalf Of Bruno
> Sent: Friday, April 23, 2004 9:51 AM
> To: u-boot-users at lists.sourceforge.net
> Subject: [U-Boot-Users] 512-Bytes EEPROM
> Hello,
> I'm porting U-Boot 1.1.0 to a board which has a
> 512-Bytes EEPROM. So, I set the define
> CFG_I2C_EEPROM_ADDR_LEN to 2, to support the 16-bit
> addresses. But the EEPROM doesn't worked fine, I can't
> even read or write it. If I set this define to 1, the
> EEPROM works properly (but only the first 256 bytes).
> So, my question is: it's necessary set another
> define/flag to user EEPROMs larger than 256 bytes?
> Thanks in advance,
> Bruno
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