Get my Udoo to see my pca9685 (I2C) - Need help

Discussion in 'UDOO X86' started by ChaoticMachinery, Oct 17, 2017.

Tags:
  1. ChaoticMachinery

    ChaoticMachinery New Member

    Joined:
    Jun 17, 2017
    Messages:
    6
    Likes Received:
    4
    Hello,

    I am trying to get the Udoo to talk to my PCA9685 board. I am running Fedora 25 and have the I2C tools and such installed.
    i2cdetect -y 0 {to 11} doesnt detect the board.

    I've connect SDA/SCL pins to the following:
    CN14 - GPIO pins 8 and 9
    CN13 - GPIO pins 14 and 15
    CN14 - pins 35 and 34

    For each connection I ran i2cdetect from 0 to 11. Nothing.

    I know the PCA9685 board works as I have used it with my Rasberry Pi 3.

    Any ideas?

    Thank you,
    K Murphy
     
  2. ChaoticMachinery

    ChaoticMachinery New Member

    Joined:
    Jun 17, 2017
    Messages:
    6
    Likes Received:
    4
    Am assuming I am missing a kernel module.

    Any suggestions?
     
  3. jas-mx

    jas-mx Active Member

    Joined:
    Dec 31, 2013
    Messages:
    407
    Likes Received:
    118
    Firstly check that the PCA9685 can accept 1.8v as a HIGH-level input voltage. Secondly you try enabling the kernel driver although from reviewing the driver source it needs to be bound to the correct i2c port which on the rpi is done through the dts file.
     
  4. ChaoticMachinery

    ChaoticMachinery New Member

    Joined:
    Jun 17, 2017
    Messages:
    6
    Likes Received:
    4
    Ok. Re-read the docs for the Braswell. So my PCA9685 is a 3.3v device. It looks like I need a bidirectional level shifter. Thats problem 1.

    Problem 2 is I guess bound the correct i2c port as you mentioned. I don't have a dts file. Kinda at a loss on that part.
     
  5. waltervl

    waltervl UDOOer

    Joined:
    Dec 12, 2015
    Messages:
    2,302
    Likes Received:
    575
    You could also try to use the Arduino i2c bus to control your board (with Arduino sketch). That is already 3.3v compliant.
     
  6. jas-mx

    jas-mx Active Member

    Joined:
    Dec 31, 2013
    Messages:
    407
    Likes Received:
    118
    Although that is possible, it does defeat the purpose of the exposing the i2c ports on the x86 side if they can't be used.
     
    Last edited: Oct 18, 2017
  7. waltervl

    waltervl UDOOer

    Joined:
    Dec 12, 2015
    Messages:
    2,302
    Likes Received:
    575
  8. jas-mx

    jas-mx Active Member

    Joined:
    Dec 31, 2013
    Messages:
    407
    Likes Received:
    118
    [QUOTE="ChaoticMachinery, post: 31152, member: 41485"
    Problem 2 is I guess bound the correct i2c port as you mentioned. I don't have a dts file. Kinda at a loss on that part.[/QUOTE]

    There is a ACPI Id "INT3492", that the kernel driver can use to determine if it needs to be activated however I don't think this will set by the BIOS. Anyway once you have the level shifters it should be visible through i2cdetect.
     
  9. ChaoticMachinery

    ChaoticMachinery New Member

    Joined:
    Jun 17, 2017
    Messages:
    6
    Likes Received:
    4
    Still bagging my head on this one.

    I've made sure the kernel has the pinctrl_cherryview module install. Hence:
    # lsmod | grep cherry
    pinctrl_cherryview 36864 3

    But I have no /sys/class/gpio directory. Any ideas what I am missing?

    A i2cdetect shows the following:
    # i2cdetect -y -l
    i2c-3 i2c i915 gmbus vga I2C adapter
    i2c-1 i2c Synopsys DesignWare I2C adapter I2C adapter
    i2c-11 smbus SMBus I801 adapter at 2040 SMBus adapter
    i2c-8 i2c DPDDC-B I2C adapter
    i2c-6 i2c i915 gmbus dpb I2C adapter
    i2c-4 i2c i915 gmbus panel I2C adapter
    i2c-2 i2c i915 gmbus ssc I2C adapter
    i2c-0 i2c Synopsys DesignWare I2C adapter I2C adapter
    i2c-9 i2c DPDDC-C I2C adapter
    i2c-10 i2c DPDDC-D I2C adapter
    i2c-7 i2c i915 gmbus dpd I2C adapter
    i2c-5 i2c i915 gmbus dpc I2C adapter

    Thank you for any help.
     

Share This Page