[U-Boot-Users] SPD EEPROM Addresses on Ebony

Wolfgang Denk wd at denx.de
Mon May 22 01:49:57 CEST 2006

In message <513a5e60605211549v34ee26bfq313e93195c2479e3 at mail.gmail.com> you wrote:
> The u-boot/include/configs/ebony.h file has the following #defines (line 13=
> 6):
> #define CONFIG_SPD_EEPROM               /* Use SPD EEPROM for setup     */
> #define SPD_EEPROM_ADDRESS {0x53,0x52}  /* SPD i2c spd addresses        */
> The PPC440GP evaluation board user's manual says on Page 63 (also on
> Page 46) that the SPD EEPROM addresses are 0xA6, 0xA7 (for DIMM0) and
> 0xA4, 0xA5 (for DIMM1).
> Why is there a difference between these addresses?  Am I even looking
> at the right addresses or am I totally missing something?

There is actually no difference. I2C addresses are 7 bit  and  occupy
the  7 high order bits in a byte. The LSB is used to indiccat read or
write accesses.

So you get: DIMM0: 0xA6 >> 1 = 0x53
                   0xA7 >> 1 = 0x53

       and: DIMM1: 0xA4 >> 1 = 0x52
                   0xA5 >> 1 = 0x52

You see?

Best regards,

Wolfgang Denk

Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
If a packet hits a pocket on a socket on a port,
And the bus is interrupted as a very last resort,
And the address of the memory makes your floppy disk abort,
Then the socket packet pocket has an error to report! - Ken Burchill?

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