Writing EEPROM Using I2C Commands over U-Boot

[Buğra AYDOĞAR]

Hi folks,

We have custom Am335x board with eeprom.We want to shape our eeprom like BeagleBone (I mean name,version,serial etc...).

I tried with U-Boot using I2C commands.You can see my logs below. Firstly i read my eeprom, then i tried to write byte by btye.Then i read again but nth happened.Then i tried to fill with 0xAA again it didnt succeed. How do you do it? By the way,I ported and used U-Boot 2011.09 for this purpose.I used i2c-tool over Linux but it says UU which means driver is used by Linux and it doesnt let me dump or anything else. 

What do you suggest to move on?

Regards,

Buğra

U-Boot# i2c probe

Valid chip addresses: 24 48 4F 50 51

U-Boot# i2c dev 1

Setting bus to 1

U-Boot# i2c dev 0

Setting bus to 0

U-Boot# i2c md 0x50 0 0x10

0000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................

U-Boot# i2c mm 0x50 0

00000000: ff ? AA

00000001: ff ? BB

00000002: ff ? CC

00000003: ff ? DD

00000004: ff ? U-Boot# <INTERRUPT>

U-Boot# <INTERRUPT>

U-Boot#

U-Boot#

U-Boot# i2c md 0x50 0 0x10

0000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................

U-Boot#

U-Boot# i2c mw 0x50 0 0x10 0xAA

U-Boot# i2c md 0x50 0 0x10

0000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................

U-Boot# i2c md 0x50 0 0x10

0000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................

[Gerald Coley]

Is your EEPROM write protected?

Gerald

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Gerald

 

ger...@beagleboard.org

g-co...@ti.com

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[Buğra AYDOĞAR]

Hi Gerald,

No, it is not write protected.

I wrote my EEPROM over Linux using Sysfs last night.

I dont remember exactly (I dont have my development board right now) but it did sth like that

cd sys/bus/i2c/devices/1-0050/

echo 12345678 >eeprom

In case, the value which you wrote above is ASCII so you will see 31:32:33:34:35:36:37:38 in your EEPROM. Here is converter .(http://www.dolcevie.com/js/converter.html)

I think U-Boot I2C commands have some problems.It also doesnt  always read BeagleBone's EEPROM correctly.(%50 sucessfully show BeagleBone's header and magic number.) . Maybe it is about U-Boot version. I also looked with scope, it really sent data to EEPROM  but I dont know exactly.

As a result my problem is solved but it is more logicial  to write EEPROM over U-Boot.

Regards,

Buğra

[Juanjo]

Have seen similar problems. Sometimes U-Boot has problems reading I2C EEPROM, on Robert Nelson version it even gives exception when changing to I2C 2 bus :)

BTW it seems matter how you read the I2C, bytes, words, etc. I2C "Beagle" standard is 16 bits words and 16 bits addressing.

[Gerald Coley]

Does your I2C lines have sufficient pullups on them? Should be around 4.7K.

Gerald

[Tom Rini]

On Wednesday, October 31, 2012 5:02:18 AM UTC-7, Juanjo wrote:

Have seen similar problems. Sometimes U-Boot has problems reading I2C EEPROM, on Robert Nelson version it even gives exception when changing to I2C 2 bus :)

Note that on mainline U-Boot (which I assume Robert's build is based on), there's also the eeprom command that will batch write from DRAM to the EEPROM.  So you could use 'mw' to setup an area of memory with the right contents or even hexedit a file on your host and then load the file to memory, write the memory to EEPROM.

--
Tom

[great...@gmail.com]

hi every body  

valid command in uboot  is   i2c mw 0x50.0  AA    1 --->times of  reading 

                                                     0x50.0   write b

                                                     0x50.1  write w

                                                     0x50.2  write  long  

[avde...@ncsu.edu]

Hi 

I don't understand the what you mean by "write b" or "write long". Could you please give the exact statements to execute? I believe the header the bootloader is looking for is "0xEE3355AA". Is that correct?

Thanks and Regards,

Abhijeet

[John Nash]

Hi Buğra AYDOĞAR,

you said "In case, the value which you wrote above is ASCII so you will see 31:32:33:34:35:36:37:38 in your EEPROM.",but how I can see it 

在 2012年10月31日星期三UTC+8下午2时39分12秒，Buğra AYDOĞAR写道：

[kavitha bk]

Yes the eeprom write in U-boot wont work as they might be 16 bit adressses or 16 bit data 

Modify the i2c driver to make it work in U-boot or write a new Uboot command to access the eeprom

Thanks 

Kavitha

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