[UP2] How to select I2C speed mode ?

hgemini New Member Posts: 17
edited October 2019 in UP Squared Linux


I am using UP2 with Ubuntu 16.04 and want to utilize I2C.
Default speed seems to be 400kHz and want to select standard mode.

I tried to find the menu for selecting I2C speed in BIOS, but cannot find.

BIOS version is UPA1AM40.

Could you please let us know how to change I2C speed ?

Best regards



  • hgemini
    hgemini New Member Posts: 17

    I have updated BIOS to 4.6 (seems to be the latest) and found no selecting I2C speed yet.

  • mdostie
    mdostie New Member Posts: 4
    edited October 2019

    Similar situation in my case. I found the settings in the BIOS menu and selected the 100 kHz speed. However this value seems to be overwritten by the OS (Ubuntu Server 18.04 with Up Kernel 4.15.0-37-generic) during the booting. As soon as I send something to the I2C pin (27, 28), the clock frequency is close to 380 kHz, whether it is echoing something to /dev/i2c-4 or running a Python script with the smbus2 package. Next step for me is to modify the I2C driver code inside the kernel source code and to build it afterwards. Any idea?

  • Dan O'Donovan
    Dan O'Donovan Administrator, Moderator, Emutex Posts: 241 admin

    Hi @hgemini , @mdostie

    We're investigating this issue now. I'll post back here as soon as I have an answer. Thanks for your patience.


  • mlkcampion
    mlkcampion New Member, Moderator, Emutex Posts: 1 admin

    Hi @hgemini , @mdostie

    We have tested the I2C speeds on UP Squared with

    BIOS version UPA1AM40 and
    BIOS version UPA1AM46

    on Ubuntu 18.04, kernel version 4.15.0-37-generic

    We can confirm that speeds selected in the BIOS are correctly applied.

    We have added a guide to the UP Wiki to provide the steps for changing the I2C speed on UP Squared, please check the following link:


    Hope this helps!

    Mike @ Emutex

  • niharG
    niharG New Member Posts: 7

    Hi @mlkcampion @Dan O'Donovan
    I'm running UP2 with Ubuntu 18.04 and the R5.0 BIOS, but it looks completely different from what the wiki shows and does not have any options for configuring I2C speed. How do I set Fast Mode on this BIOS?

  • rogertsai(AAEON)
    rogertsai(AAEON) New Member Posts: 350 ✭✭✭

    Press "del" enter bios password screen, then Enter the BIOS password with "upassw0rd" and you will have access to settings which is CRB setup

    To change the speed of I2C in BIOS, Main > CRB Setup > CRB Chipset > South Cluster Configuration > LPSS Configuration