AIO-3399J Buy Spec

Uses RK3399 Six-Core ( A72x2+A53x4 ) 64-Bit CPU, up to 2.0Ghz , integrated Quad-Core Mali-T864 GPU. Onboard M.2 PCIe, 4G LTE interface, multiple display interface and serial port. Support Android/Linux/Ubuntu system.

RTC

Update time:2018-04-16 Views:1121

Introduction

There are one RTC(Real Time Clock) integrated in RK808 on the AIO-3399J .The main capabilities are clock, calendar,alarm, timer, and two 32KHz clock ouput.

Connect CR2032  to J3 for providing rtc power if want to keep rtc running when main power goes off. connect like the following picture:

英文_02.jpg

Driver

RTC's DTS information  integrated in rk808 note

driver path: drivers/rtc/rtc-rk808.c

Interface

Linux has three main userspace RTC API:

  • SYSFS:/sys/class/rtc/rtc0/

  • PROCFS: /proc/driver/rtc

  • IOCTL: /dev/rtc0

SYSFS

you can use cat/echo to operate the interfaces in /sys/class/rtc/rtc0/.

for example, you can check date/time like this:

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

and set the boot time, such as boot after 120s:

echo +120 >  /sys/class/rtc/rtc0/wakealarm
cat /sys/class/rtc/rtc0/wakealarm
reboot -p

PROCFS

List RTC information:

# cat /proc/driver/rtc                                                                                       rtc_time        : 09:34:59                                                                                                             rtc_date        : 2013-01-18                                                                                                           alrm_time       : 08:52:45                                                                                                             alrm_date       : 2013-01-18                                                                                                           alarm_IRQ       : no                                                                                                                   
alrm_pending    : no                                                                                                                   
update IRQ enabled      : no                                                                                                           
periodic IRQ enabled    : no                                                                                                           
periodic IRQ frequency  : 1                                                                                                            max user IRQ frequency  : 64                                                                                                           24hr            : yes

IOCTL

The ioctl() calls supported by /dev/rtc0 are also supported by the RTC class framework.
Please refer to rtc.txt  for detailed instructions.

FAQs

Q1: RTC clock does not  synchronize after power on
A1: check whether the battery connect to the J2.