Difference between revisions of "RTC"
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== Hardware == | == Hardware == | ||
| − | No permanent RTC is present on the APF9328 but it is not so complex to add a DS1374 (with | + | No permanent RTC is present on the APF9328 but it is not so complex to add a DS1374 (with integrated quartz) on the I2C bus. Do not forget to provide the two power-supply (VCC and Vbackup). |
== Configuration == | == Configuration == | ||
Revision as of 17:17, 27 July 2008
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.
Contents
[hide]Hardware
No permanent RTC is present on the APF9328 but it is not so complex to add a DS1374 (with integrated quartz) on the I2C bus. Do not forget to provide the two power-supply (VCC and Vbackup).
Configuration
First be sure to use an armadeus 2.0 or higher. The RTC/DS1374 support is already configured 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
Installation is automatic with the default configuration but 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
you will get something like this :
$ dmesg | grep rtc <6>ds1374 0-0068: rtc intf: sysfs <6>ds1374 0-0068: rtc intf: proc <6>ds1374 0-0068: rtc intf: dev (254:0) <6>ds1374 0-0068: rtc core: registered ds1374 as rtc0
Usage
- From U-Boot there is a command date to read, reset, update the RTC.
$ help date for more information $ date reset to be done after battery exchange to remove message ### Warning: RTC oscillator has stopped $ date 013122302007 to set the date January 31th 2007 22h30.
- From linux use the commande hwclock to read, write, synchronize the RTC and date to read and update system date and time.
$ hwclock --help $ hwclock -r to read hardware clock and print result $ hwclock -s to set the system time from the hardware RTC clock $ hwclock -w to set the hardware RTC clock to the current system time
$ date --help for more information $ date -R to read hardware clock and print result $ date 013122302007 to sets the system date january 31th 2007 22h30.
- Then, when booting you will see something like this:
ds1374 0-0068: setting the system clock to 2007-09-09 17:35:51 (1189359351)
Links
- maxim-ic ds1374 datasheet http://datasheets.maxim-ic.com/en/ds/DS1374-DS1374U.pdf
