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DM814x EZSDK I2C question

Jian Wu1
Intellectual 360 points

Other Parts Discussed in Thread: PCF8575, TVP7002

Hello ,

my board : dm814x

my ezsdk : ti-ezsdk_dm814x-evm_5_03_01_15

I want to access I2c device mxt224 (0x4a) and pcf8575 (0x21)

This is my log:

root@dm814x-evm:/# i2cdetect -l
i2c-1   i2c             OMAP I2C adapter                        I2C adapter
i2c-3   i2c             OMAP I2C adapter                        I2C adapter
root@dm814x-evm:/# i2cdetect -r 1
WARNING! This program can confuse your I2C bus, cause data loss and worse!
I will probe file /dev/i2c-1 using read byte commands.
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: -- -- -- -- -- -- -- -- UU -- -- -- -- -- -- --
20: 20 UU -- -- -- -- -- -- -- -- -- -- -- 2d -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: UU 41 -- -- -- -- -- -- 48 -- UU -- -- -- -- --
50: 50 51 -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --                         
root@dm814x-evm:/#

According to the below:

root@dm814x-evm:/sys/devices/platform/omap/omap_i2c.1/i2c-1# ls
1-0018         1-0023         1-0050         i2c-dev        power
1-0020         1-0040         delete_device  name     subsystem
1-0021         1-004a         device         new_device     uevent

The device 18, 20, 21,23, 40,4a and 50 should be detected. but why they can't and instead of showing "UU"?

Thanks very much,

Jian

  • 0
    TI__Expert 5660 points

    Hi,

    Each cell in the output table of i2cdetect will contain one of the following symbols:

    • "--". The address was probed but no chip answered.
    • "UU". Probing was skipped, because this address is currently in use by a driver. This strongly suggests that there is a chip at this address.
    • An address number in hexadecimal, e.g. "2d" or "4e". A chip was found at this address.

    Regards,

    Nageswari

  • 0 in reply to Nageswari Srinivasan
    Intellectual 610 points

    Understand that in the EZSDK release, the dual ARM M3s that form the media controller have control over the I2C bus that speaks to the TVP7002 on the main board, as well as other devices.

    A PSP is available that removes this restriction, placing all I2C control in the hands of the ARM Cortex A8. This package is required for use of V4L2 for capture initialization, but may have negative effects on GStreamer and various demos. Search on "V4L2" in this subform for details. Useful posts will be from December or January.