jsobota
Posts: 42
Joined: Tue Jul 10, 2012 3:24 pm
Location: Plzen, Czech Republic

Overlay for MCP79410 RTC

Mon Apr 13, 2015 4:45 pm

I am trying to make the MCP79410 RTC chip working in Raspbian. The UniPi extension board is using this chip. I have an overlay file which I am able to compile (see below). Afterwards I can access the RTC data via hwclock when I add to /boot/config.txt:

Code: Select all

dtoverlay=mcp7941x-rtc
However, udev is not recognizing the device. Moreover, I would like to have an overlay which can be used as a parameter to the i2c-rtc overlay, just like in the case of ds1307, ds3231, etc.

Any hints on turning the MCP79410 RTC chip into a standard RTC device (in terms of Raspbian)?

The mcp7941x-rtc-overlay.dts file:

Code: Select all

/dts-v1/;
/plugin/;

/ {
    compatible = "brcm,bcm2708";
    fragment@0 {
        target = <&i2c1>;

        __overlay__ {
            /* shut up DTC warnings */
            #address-cells = <1>;
            #size-cells = <0>;

            /* UniPi mcp7941x RTC module */
            rtc@6f {
                compatible = "dallas,mcp7941x";
                reg = <0x6f>;
            };
        };
    };
};

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