RTC

On this page, you will find usefull informations to use an external DS1374 Real Time Clock. This feature apply to the armadeus software release 2.0 and above.

Hardware

No permanent RTC is present on the APF9328 but it is not so complex to add a DS1374 (with quartz integrated) on the I2C bus. Do not forget to provide the power-supply.

Configuration

First be sure to use an armadeus 2.0 or higher. The RTC/DS1374 support is already present in U-BOOT and linux kernel 2.6.18.1 and higher. Therefore you have nothing to configure to use the RTC. Nevertheless these are the parameters to check to have the RTC supported:

$ make linux-menuconfig

• check the i2c module drivers "I2C support", "I2C DEVICE", "I2C HARDWARE/bus on imx"
• check the RTC module driver "RTC class", "set time from RTC" "RTC interface dev"
• if you integrates these module statically in the kernel then the system date will be set at power-up.

$ make

and reload your kernel and/or rootfs

Installation

if you choose to compile rtc and i2c drivers as module then you have load them:

$ modprobe i2c-imx
$ modprobe rtc-ds1374
$ modprobe rtc-dev

Usage

• From U-Boot there is a command date to read, reset, update the RTC.

$ help date

for more information

• From linux use the commande hwclock to read, write, synchronize the RTC.

$ date --help 

for more information

Links

• maxim-ic ds1374 datasheete