Hello,
still not pleased with the accuracy of the builtin rtc of my banana pi, I added a ds3231 module similar to the one described at https://thepihut.com/blogs/raspberry-pi-tutorials/17209332-adding-a-real-time-clock-to-your-raspberry-pi to it.
With that, I noticed two things:
- The example I started with at https://github.com/armbian/sunxi-DT-overlays/blob/master/examples/i2c-ds1307.dts contains a typo (a space too much between * and /) at line 11.
- It is not completely easy to have an external rtc chip being the default rtc for the board.
Anyway, here is the overlay I ended up with:
/dts-v1/;
/plugin/;
/ {
compatible = "allwinner,sun4i-a10", "allwinner,sun7i-a20", "allwinner,su
n8i-h3", "allwinner,sun50i-a64", "allwinner,sun50i-h5";
/*
* Aliases can be used to set the external RTC as rtc0
* Needs supplying the correct path to the I2C controller RTC is connect
ed to,
* this example is for I2C1 on A20
*/
fragment@0 {
target-path = "/aliases";
__overlay__ {
rtc1 = "/soc@01c00000/rtc@01c20d00";
};
};
fragment@1 {
target-path = "/aliases";
__overlay__ {
rtc0 = "/soc@01c00000/i2c@01c2b400/ds3231@68";
};
};
fragment@2 {
target = <&i2c2>;
__overlay__ {
#address-cells = <1>;
#size-cells = <0>;
ds3231@68 {
compatible = "maxim,ds3231";
reg = <0x68>;
status = "okay";
};
};
};
};
Works fine through armbian-add-overlay and is currently in works-for-me state.
Added bonus: the chip has a temperature sensor:
# sensors
ds3231-i2c-1-68
Adapter: mv64xxx_i2c adapter
temp1: +19.8°C
Bye,
Joerg
P.s.: These rtc-board are available also from your Chinese hardware crap dealer of least distrust for less than 1 USD.
