Adding a peripheral real time clock with ncs 1.8.0 SDK over I2C

[jake11212]

I'm trying to interface with the ds1339 real time clock to set and read the time for timestamping tasks in ncs 1.8.0.  I've found a few tutorials that boil down to:

1. add the dts child node under the i2c controller node: in my overlay file I changed to this:

&i2c1 {

    compatible = "nordic,nrf-twim";

    status = "okay";

    sda-pin = < 22 >;

    scl-pin = < 23 >;

    clock-frequency = <I2C_BITRATE_STANDARD>;  

    ds1339@68 {

        compatible = "maxim,ds1339";

        reg = <0x68>;

        label = "ds1339";

    };

};

My question here is: are the sda and scl pins in this overlay being defined on the 52dk I'm using?  So I then just need to connect my rtc pins to these pins?

2. create a binding

For this I went to ..\ncs\v1.8.0\zephyr\dts\bindings\rtc and added a .yaml file called maxim,ds1339 with contents:

description: Maxim DS1339 I2C RTC

compatible: "maxim,ds1339"

include: i2c-device.yaml

Is anything else needed here?

3. create a driver

This part was the most confusing.  I went to ..\ncs\v1.8.0\zephyr\drivers\counter which had a number of RTC drivers such as counter_mcux_rtc and counter_mcux_lpc_rtc which both seemed like they may work.  But I wasn't sure if this needed to be made specifically for my ds1339. 

Do I need to write a specific driver for my device?  How do I go about completing this section and what is needed to build and interface with the ds1339?

To my prj.config I added 

CONFIG_I2C=y
CONFIG_I2C_1=y

Is there anything else that I need to add to configure the drivers and I2C for the device?

Thanks

[Hakon]

Hello,

there is no driver for ds1339, so that will most likely not work, unless you create one yourself. You can try the ds3231 driver, and use the zephyr\samples\drivers\counter\maxim_ds3231 sample. It's possible that you need to make some modifications to the zephyr\drivers\counter\maxim_ds3231.c file in order for it to work.