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Last Post 29 Oct 2013 02:35 PM by  Andreas Gschossmann
Using I2C0 Bus when Battery is Not Being Used?
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steven.eckhoff
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25 Oct 2013 09:37 AM
    Hello,

    I have a question about the I2C-ports of the logicpd "L138 SOM-M1". According to the "OMAP-L138 SOM-M1 Hardware Specification" the SOM has the following I2C ports:


    - I2C0, pin 60 and 62 of J2
    - I2C1, pin 97 and 99 of J1

    The Spec sais that I2C0 bus is used for communication between the OMAP-L138 processor and the TPS65070 PMIC. This Chip is used for battery management. I am not using any battery in my device. If I can do without this functionality, is it possible to use this I2C port for own purposes?
    steven.eckhoff
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    25 Oct 2013 10:23 AM
    You cannot reconfigure the signal for a use different from I2C. The PMIC does more than battery management. It also does power sequencing and resets which is critical to the system. If you are going to use the signal for I2C purposes make sure to not overload the bus. The maximum capacitance is 400pF which is outlined in the I2C specification[1]. In general make sure anything using the I2C bus does not interfere with the PMIC communication from the processor.

    [1] http://www.nxp.com/docume...r_manual/UM10204.pdf
    Andreas Gschossmann
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    29 Oct 2013 02:35 PM
    Thank you for this information Steven.

    I will not have many members on the bus, however I am expecting have a lot of communication on it. In order to prevent the bus to be blocked by this, I prefer to use I2C1. Since I2C1 shares its function with UART2, which seems to be the default terminal of the Linux system, I hope it is possible to reconfigure the U-Boot and the Linux System to use UART0 or UART1 for terminal purposes.
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