I am using i2cset just fine on my BBB of P9 19 and 20, it is currently Bus1.
My notes:
i2c detect on Bus1, see my address at 4C and 4D:
i2cdetect -r -y 1
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- UU -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- *4c 4d* -- --
50: -- -- -- -- UU UU UU UU -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
Dump the 4C device registers, register 0x14 is 0x*00*:
i2cdump -y 1 0x4c
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 00 00 00 11 31 00 00 20 00 00 01 7c 10 00 00 ....?1.. ..?|?..
10: 00 00 00 10 *00* 10 00 00 01 00 80 01 0f 03 07 04 ...?.?..?.??????
20: 00 00 00 04 00 08 f3 04 13 00 11 1f 00 00 00 00 ...?.????.??....
30: 00 00 00 00 00 00 00 00 00 00 00 00 00 30 30 22 .............00"
40: 02 04 14 05 00 00 00 00 55 00 00 00 00 00 00 00 ????....U.......
50: 00 00 00 00 00 07 00 00 81 00 00 00 00 40 78 15 .....?..?....@x?
60: 01 10 00 00 00 01 0f 03 07 11 00 00 00 00 06 03 ??...?????....??
70: 02 83 03 00 04 00 80 01 00 00 00 00 00 00 00 00 ???.?.??........
80: 00 00 00 00 11 31 00 00 20 00 00 01 7c 10 00 00 ....?1.. ..?|?..
90: 00 00 00 10 00 10 00 00 01 00 80 01 0f 03 07 04 ...?.?..?.??????
a0: 00 00 00 04 00 08 f3 04 13 00 11 1f 00 00 00 00 ...?.????.??....
b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 30 30 22 .............00"
c0: 02 04 14 05 00 00 00 00 55 00 00 00 00 00 00 00 ????....U.......
d0: 00 00 00 00 00 07 00 00 81 00 00 00 00 40 78 15 .....?..?....@x?
e0: 01 10 00 00 00 01 0f 03 07 11 00 00 00 00 06 03 ??...?????....??
f0: 02 83 03 00 04 00 80 01 00 00 00 00 00 00 00 00 ???.?.??........
Write 0x*01* to register 0x14:
i2cset -y 1 0x4c 0x14 0x*01*
Dump the registers and not the change to 0x*01*:
i2cdump -y 1 0x4c
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 00 00 00 11 31 00 00 20 00 00 01 7c 10 00 00 ....?1.. ..?|?..
10: 00 00 00 10 *01* 10 00 00 01 00 80 01 0f 03 07 04 ...???..?.??????
20: 00 00 00 04 00 08 f3 04 13 00 11 1f 00 00 00 00 ...?.????.??....
30: 00 00 00 00 00 00 00 00 00 00 00 00 00 30 30 22 .............00"
40: 02 04 14 05 00 00 00 00 55 00 00 00 00 00 00 00 ????....U.......
50: 00 00 00 00 00 07 00 00 81 00 00 00 00 40 78 15 .....?..?....@x?
60: 01 10 00 00 00 01 0f 03 07 11 00 00 00 00 06 03 ??...?????....??
70: 02 83 03 00 04 00 80 01 00 00 00 00 00 00 00 00 ???.?.??........
80: 00 00 00 00 11 31 00 00 20 00 00 01 7c 10 00 00 ....?1.. ..?|?..
90: 00 00 00 10 01 10 00 00 01 00 80 01 0f 03 07 04 ...???..?.??????
a0: 00 00 00 04 00 08 f3 04 13 00 11 1f 00 00 00 00 ...?.????.??....
b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 30 30 22 .............00"
c0: 02 04 14 05 00 00 00 00 55 00 00 00 00 00 00 00 ????....U.......
d0: 00 00 00 00 00 07 00 00 81 00 00 00 00 40 78 15 .....?..?....@x?
e0: 01 10 00 00 00 01 0f 03 07 11 00 00 00 00 06 03 ??...?????....??
f0: 02 83 03 00 04 00 80 01 00 00 00 00 00 00 00 00 ???.?.??........
Works for me!
On Thu, Aug 14, 2014 at 3:18 PM, Brandon I <[email protected]> wrote:
> I think this can only mean that a device isn't responding to the address
> you're providing. Did you set the i2c device address to the same value used
> with i2ctest?
>
>
> On Thu, Aug 14, 2014 at 10:09 AM, Akhil Panyamparambil <
> [email protected]> wrote:
>
>> Hi all. Can you guys help me.I am using beaglebone black i2c2 pin 19 and
>> 20 of p9. Somewhere in the net it was told i2c2 has told accessed with
>> i2c-1 in /dev folder. I am booting default amstrom linux from emmc.
>> Hardware is completely checked and verified. I have connected 3 io
>> expansion modules to i2c bus. I can communicate to them by i2ctest commands
>> from command line. But the problem is with the file writes. I cant write to
>> /dev/i2c-1 file with "write" function. The file descriptor doeant have an
>> error. Also the ioctl calls doest make any errors. But the write function
>> is having problem. And thus I cant access i2c bus in application layer.
>>
>> --
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