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Beaglebone Black: how to use RTC DS1307/DS1338 with Android?

Matthias_zurich
Prodigy 20 points

Hello

I am usinge the TI-Android-JB-4.2.2-DevKit-4.1.1 to build an Android for Beaglebone Black which works perfectly well. I try to use the RTC-Cape (http://elinux.org/CircuitCo:RTC_Cape). With the "onboard" Angström on the BBB I was able to set and read the RTC manually, therefore I assume that the hardware is ok.

To put the RTC in operation with Android, I added in the file kernel/arch/arm/mach-omap2/board-am335xevm.c in the struct static struct i2c_board_info __initdata am335x_i2c0_boardinfo[] at the end

{
    I2C_BOARD_INFO("ds1338", 0x68),
},

In kernel/arch/arm/configs/am335x_evm_android_defconfig I activated the CONFIG_RTC_DRV_DS1307 (CONFIG_RTC_DRV_DS1307=y) and deactivated the CONFIG_RTC_DRV_OMAP.

At bootup it says

<4>[    1.880767] rtc-ds1307: probe of 1-0068 failed with error -5
<6>[    1.886779] i2c /dev entries driver

and

<3>[    2.306884] drivers/rtc/hctosys.c: unable to open rtc device (rtc0)


I am new to Android/Linux kernel configuration. How do I have to include and configure the RTC in the kernel that it is usable at bootup? Can anyone give some advice?


Best regards

Matthias

  • 0
    Prodigy 20 points

    A temporary solution was found here: http://stackoverflow.com/questions/25133760/beaglebone-black-rtc-ds1307-ds1338-gives-error-in-android-at-bootup

    (It requires some soldering. A more elegant solution would be to activate i2c-2 in the kernel.)