RTC

Introduction

The AIO-1126BJD4V0 development board uses the RV1126B chip's internal
peripherals as the RTC (Real Time Clock). It provides year, month,
day, weekday, hour, minute, and second based on a 32.768 kHz crystal
oscillator. Second and hour count compensation is supported. BCD
indicates time, calendar, and alarm. It supports 12 or 24-hour format,
with AM and PM in 12-hour mode.

Interrupts can be individually masked by software.  Alarm interrupt
Periodic interrupt  Chip power-off interrupt  Battery power atypical
interrupt

This RTC peripheral does not support timed sleep/wake-up.

Driver RTC

DTS configuration reference in Linux SDK:
"kernel-6.1/arch/arm64/boot/dts/rockchip/rv1126b-firefly-aio-
1126bjd4v0.dts"

   &rtc {
           rockchip,rtc-suspend-bypass;
           status = "okay";
   };

Driver Reference: "kernel-6.1/drivers/rtc/rtc-rockchip.c"

Interface usage

Linux provides three user-space call interfaces. The corresponding
path in the AIO-1126BJD4V0 development board is:

SYSFS Interface : /sys/class/rtc/rtc0/

PROCFS Interface : /proc/driver/rtc

IOCTL Interface : /dev/rtc0

SYSFS Interface

You can directly use the interface below "cat" and "echo" operations
"/sys/class/rtc/rtc0/".

For example, check the date and time of the current RTC:

   # cat /sys/class/rtc/rtc0/date
   2013-01-18
   # cat /sys/class/rtc/rtc0/time
   09:36:10

PROCFS Interface

Print RTC related information:

   # cat /proc/driver/rtc
   rtc_time        : 06:53:50
   rtc_date        : 2022-06-21
   alrm_time       : 06:55:05
   alrm_date       : 2022-06-21
   alarm_IRQ       : yes
   alrm_pending    : no
   update IRQ enabled      : no
   periodic IRQ enabled    : no
   periodic IRQ frequency  : 1
   max user IRQ frequency  : 64
   24hr            : yes

IOCTL Interface

You can use "ioctl" to control "/dev/rtc0".

Please refer to the document "rtc.txt" for detailed instructions.

FAQs

Q1: The time is out of sync after the development board is powered on
?

A1 :

  Check that the RTC battery is properly connected