Jean Delvare <khali@...> writes:
>
> Hi Chris,
>
> On Fri, 17 Apr 2009 10:33:38 -0400, Chris Cole wrote:
> > Hey all, I found the i2c-tools and lm-sensors packages today...great
> > stuff! I had a question about using i2cset properly. I'm trying to set
> > the value of a digital potentiometer (maxim 5434L) over the i2cbus, and
> > I can tell by using i2cdump that it's setting the register value
> > properly...but I keep getting "Warning - readback failed" after i use
> > i2cset. Here's the output of what I'm trying to do:
> >
> > ccole <at> test:~$ sudo modprobe scx200_acb
> > ccole <at> test:~$ sudo modprobe i2c-dev
> > ccole <at> test:~$ sudo su -
> > root <at> test:~# i2cdetect -l
> > i2c-0 smbus CS5536 ACB0 SMBus adapter
> >
> > root <at> test:~# i2cdetect 0
> > WARNING! This program can confuse your I2C bus, cause data loss and worse!
> > I will probe file /dev/i2c-0.
> > I will probe address range 0x03-0x77.
> > Continue? [Y/n] y
> > 0 1 2 3 4 5 6 7 8 9 a b c d e f
> > 00: -- -- -- -- -- -- -- -- -- -- -- -- --
> > 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> > 20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> > 30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> > 40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> > 50: 50 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> > 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> > 70: -- -- -- -- -- -- -- --
> > root <at> test:~# i2cdump 0 0x50
> > No size specified (using byte-data access)
> > WARNING! This program can confuse your I2C bus, cause data loss and worse!
> > I will probe file /dev/i2c-0, address 0x50, mode byte
> > Continue? [Y/n] y
> > 0 1 2 3 4 5 6 7 8 9 a b c d e f 0123456789abcdef
> > 00: 80 08 07 0d 0b 01 40 00 04 60 70 00 82 08 00 01 ??????@.?`p.??.?
> > 10: 0e 04 0c 01 02 20 c0 75 70 00 00 48 30 48 2a 80 ????? ?up..H0H*?
> > 20: 80 80 45 45 00 00 00 00 00 3c 48 30 2d 55 00 01 ??EE.....<H0-U.?
> > 30: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 10 68 ..............?h
> > 40: 7f 7f 7f 7f 7f ba 00 00 00 56 4c 34 37 30 4c 36 ??????...VL470L6
> > 50: 7f 32 33 2d 42 33 53 00 00 00 00 00 00 00 00 00 ?23-B3S.........
> > 60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> > 70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> > 80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
> > 90: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
> > a0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
> > b0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
> > c0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
> > d0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
> > e0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
> > f0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
>
> This is the SPD EEPROM of your memory module (512 MB of PC2700 DDR
> SDRAM according to decode-dimms.) This is not your digital
> potentiometer.
>
> >
> > root <at> test:~# i2cset 0 0x50 0x50 0x21
> > No size specified (using byte-data access)
> > WARNING! This program can confuse your I2C bus, cause data loss and worse!
> > DANGEROUS! Writing to a serial EEPROM on a memory DIMM
> > may render your memory USELESS and make your system UNBOOTABLE!
>
> As the warning says, you REALLY shouldn't do this!
>
> > I will write to device file /dev/i2c-0, chip address 0x50, data address
> > 0x50, data 0x21, mode byte.
> > Continue? [y/N] y
> > Warning - readback failed
> >
> > root <at> test:~# i2cdump 0 0x50
> > No size specified (using byte-data access)
> > WARNING! This program can confuse your I2C bus, cause data loss and worse!
> > I will probe file /dev/i2c-0, address 0x50, mode byte
> > Continue? [Y/n] y
> > 0 1 2 3 4 5 6 7 8 9 a b c d e f 0123456789abcdef
> > 00: 80 08 07 0d 0b 01 40 00 04 60 70 00 82 08 00 01 ??????@.?`p.??.?
> > 10: 0e 04 0c 01 02 20 c0 75 70 00 00 48 30 48 2a 80 ????? ?up..H0H*?
> > 20: 80 80 45 45 00 00 00 00 00 3c 48 30 2d 55 00 01 ??EE.....<H0-U.?
> > 30: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 10 68 ..............?h
> > 40: 7f 7f 7f 7f 7f ba 00 00 00 56 4c 34 37 30 4c 36 ??????...VL470L6
> > 50: 21 32 33 2d 42 33 53 00 00 00 00 00 00 00 00 00 !23-B3S.........
> > 60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> > 70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> > 80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
> > 90: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
> > a0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
> > b0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
> > c0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
> > d0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
> > e0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
> > f0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
> >
> > root <at> test:~# i2cset 0 0x50 0x50 0x00
> > No size specified (using byte-data access)
> > WARNING! This program can confuse your I2C bus, cause data loss and worse!
> > DANGEROUS! Writing to a serial EEPROM on a memory DIMM
> > may render your memory USELESS and make your system UNBOOTABLE!
> > I will write to device file /dev/i2c-0, chip address 0x50, data address
> > 0x50, data 0x00, mode byte.
> > Continue? [y/N] y
> > Warning - readback failed
> >
> > root <at> test:~# i2cdump 0 0x50
> > No size specified (using byte-data access)
> > WARNING! This program can confuse your I2C bus, cause data loss and worse!
> > I will probe file /dev/i2c-0, address 0x50, mode byte
> > Continue? [Y/n] y
> > 0 1 2 3 4 5 6 7 8 9 a b c d e f 0123456789abcdef
> > 00: 80 08 07 0d 0b 01 40 00 04 60 70 00 82 08 00 01 ??????@.?`p.??.?
> > 10: 0e 04 0c 01 02 20 c0 75 70 00 00 48 30 48 2a 80 ????? ?up..H0H*?
> > 20: 80 80 45 45 00 00 00 00 00 3c 48 30 2d 55 00 01 ??EE.....<H0-U.?
> > 30: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 10 68 ..............?h
> > 40: 7f 7f 7f 7f 7f ba 00 00 00 56 4c 34 37 30 4c 36 ??????...VL470L6
> > 50: 00 32 33 2d 42 33 53 00 00 00 00 00 00 00 00 00 .23-B3S.........
> > 60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> > 70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> > 80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
> > 90: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
> > a0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
> > b0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
> > c0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
> > d0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
> > e0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
> > f0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
>
> You are very lucky that you didn't write to a byte location < 0x40,
> that would have broken the checksum and you would no longer be able to
> boot your system.
>
> I encourage you to restore the value of byte 0x50 to what it originally
> was and never ever again touch this SPD EEPROM.
>
> The "readback failed" warning is presumably because it takes some time
> to the EEPROM to write the new data and in the meantime you can't read
> from it.
>
> The MAX5434L has I2C address 0x28 or 0x29. It doesn't show on
> i2cdetect. Check whether it's properly soldered. If it is, try i2cget
> instead of i2cdetect, maybe the Maxim chip doesn't like the probes
> i2cdetect does.
>
Hi, Jean
I have the same problem than Chris. I am working with an ALIX motherboard with
voyage linux distribution and I have connected a 24LC64 eeprom. When I try to
write the epprom with i2cset command it doesn't work.
I am sure that the address of the eeprom is 0x51 because if I change it
i2cdetect shows me it in the new address (the first test I did it was in the
0x50 address, then I changed it to 0x51).
I loaded i2c-dev and i2c-core modules.
voyage:~# i2cdetect -l
i2c-0 smbus CS5536 ACB0 SMBus adapter
voyage:~# i2cdetect -y 0
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- 51 -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --
voyage:~# i2cdump -y 0 0x51
No size specified (using byte-data access)
0 1 2 3 4 5 6 7 8 9 a b c d e f 0123456789abcdef
00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
10: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
20: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
30: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
40: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
50: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
60: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
70: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
90: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
a0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
b0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
c0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
d0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
e0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
f0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
As you see the eeprom is empty. The first thing I don't understand is why
i2cdump shows only 256 bytes and not all the eeprom (64K).
If I try to write it doesn't complain, but when I dump the memory again nothing
changed.
voyage:~# i2cset -y 0 0x51 0x01 0xaa
voyage:~# i2cdump -y 0 0x51
No size specified (using byte-data access)
0 1 2 3 4 5 6 7 8 9 a b c d e f 0123456789abcdef
00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
10: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
20: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
30: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
40: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
50: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
60: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
70: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
90: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
a0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
b0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
c0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
d0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
e0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
f0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
The only way I see a change is writing in data address 0 with c mode, then in
the next dump I see 00 in 0x00 address.. BUT if I repeat the dump it prints ff
again!
voyage:~# i2cset -y 0 0x51 0 c
voyage:~# i2cdump -y 0 0x51
No size specified (using byte-data access)
0 1 2 3 4 5 6 7 8 9 a b c d e f 0123456789abcdef
00: 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
10: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
20: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
30: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
40: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
50: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
60: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
70: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
90: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
a0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
b0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
c0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
d0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
e0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
f0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
voyage:~# i2cdump -y 0 0x51
No size specified (using byte-data access)
0 1 2 3 4 5 6 7 8 9 a b c d e f 0123456789abcdef
00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
10: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
20: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
30: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
40: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
50: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
60: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
70: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
90: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
a0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
b0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
c0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
d0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
e0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
f0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
I have tried this with two different chips, the result was exactly the same.
Any idea? Any help will be apreciated!
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