I have seen many tutorials about connecting real time clock hardware on Orange Pi and Raspberry Pi.
What i didn't like was removing of fake-hwclock service, because I want that RTC works when it is connected, and fake-hwclock when RTC is not connected.
Therefore, I changed /sbin/fake-hwclock script to work in this way.
So, here is how to do this, tested on OrangePi+2E, Armbian Ubuntu legacy kernel:
Purchase cheap DS3231 module on eBay (cca. $1) like this one:
Edit /sbin/fake-hwclock and place this code in it:
Spoiler
!/bin/sh
#
# script: /sbin/fake-hwclock
# Changed by I.S. to use RTC if it is connected
#
#
# Trivial script to load/save current contents of the kernel clock
# from/to a file. Helpful as a *bootstrap* clock on machines where
# there isn't a useful RTC driver (e.g. on development boards). Using
# NTP is still recommended on these machines to get to real time sync
# once more of the system is up and running.
#
# Copyright 2012 Steve McIntyre <93sam@debian.org>
#
# License: GPLv2, see COPYING
# Config variables
# RTC is attached on bus...
i2c_bus=0
eeprom_address="57"
rtc_address="68"
# Orange PI +2e have RTC, so our device will be:
rtc_device="rtc1"
# fake-hwclock is using cron.hourly to periodically save system clock
cronfile="/etc/cron.hourly/fake-hwclock"
# If you want to periodically synchronize rtc with system time, change this to true
update_rtc_periodically=false
# End of config variables
# I don't know are all needed programs in PATH,
# therefore I'll declare all mine
echo="/bin/echo"
i2cdetect="/usr/sbin/i2cdetect"
grep="/bin/grep"
awk="/usr/bin/awk"
ln="/bin/ln"
hwclock="/sbin/hwclock"
readlink="/bin/readlink"
progs="$echo $i2cdetect $grep $awk $ln $hwclock $readlink"
check_external_progs(){
not_found=""
prog=""
for prog in ${progs}
do
if [ ! -e "$prog" ]; then
not_found=$prog" "$not_found
echo "Required program not found: $prog"
fi
done
if [ "$not_found"x = ""x ] ; then
progs_ok=true
else
progs_ok=false
fi
unset not_found
unset prog
}
recreate_cronjob() {
if [ ! -e "$1" ]; then
cat << 'EOF' > "$1"
#!/bin/sh
#
# Simple cron script - save the current clock periodically in case of
# a power failure or other crash
if (command -v fake-hwclock >/dev/null 2>&1) ; then
fake-hwclock save
fi
EOF
fi
}
is_rtc_connected(){
check_external_progs
if $progs_ok; then
list=$($i2cdetect -y "$i2c_bus")
rtc=$(echo "$list" | $grep "60:" | $awk '{print $10}')
eeprom=$(echo "$list" | $grep "50:" | $awk '{print $9}')
if [ "$eeprom" -eq "$eeprom_address" ]; then
case $rtc in
"UU")
t="/dev/$rtc_device"
r=$($readlink -f /dev/rtc)
if [ "$r"="$t" ]; then
$echo "true"
else
$ln -sf /dev/$rtc_device /dev/rtc >/dev/null 2>&1
if [ "$r"="$t" ]; then
$echo "true"
else
$echo "false"
fi
fi;;
$rtc_address)
$echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-0/new_device
sleep 5
$ln -sf /dev/$rtc_device /dev/rtc >/dev/null 2>&1
t="/dev/$rtc_device"
r=$($readlink -f /dev/rtc)
if [ "$r"="$t" ]; then
$echo "true"
else
$echo "false"
fi;;
*)
$echo "false";;
esac
else
$echo "false"
fi
else
$echo "false"
fi
}
# Is RTC installed?
rtc_installed=$(is_rtc_connected)
if $rtc_installed; then
# We dont need periodically saving
rm -f "$cronfile" >/dev/null 2>&1
else
# Restore periodically saving
recreate_cronjob "$cronfile"
fi
if [ "$FILE"x = ""x ] ; then
FILE=/etc/fake-hwclock.data
fi
COMMAND=$1
if [ "$COMMAND"x = ""x ] ; then
COMMAND="save"
fi
FORCE=false
if [ "$2"x = "force"x ] ; then
FORCE=true
fi
case $COMMAND in
save)
if $rtc_installed; then
#$echo "RTC save"
$hwclock -w
if $update_rtc_periodically; then
$echo "cronjob restore"
recreate_cronjob "$cronfile"
fi
else
if [ -e $FILE ] ; then
SAVED="$(cat $FILE)"
SAVED_SEC=$(date -u -d "$SAVED" '+%s')
NOW_SEC=$(date -u '+%s')
if $FORCE || [ $NOW_SEC -ge $SAVED_SEC ] ; then
date -u '+%Y-%m-%d %H:%M:%S' > $FILE
else
echo "Current system time: $(date -u '+%Y-%m-%d %H:%M:%S')"
echo "fake-hwclock saved clock information is in the future: $SAVED"
echo "To force the saved system clock backwards anyway, use \"force\""
fi
else
date -u '+%Y-%m-%d %H:%M:%S' > $FILE
fi
fi
;;
load)
if $rtc_installed; then
#$echo "RTC load"
$hwclock -s
else
if [ -e $FILE ] ; then
SAVED="$(cat $FILE)"
SAVED_SEC=$(date -u -d "$SAVED" '+%s')
NOW_SEC=$(date -u '+%s')
if $FORCE || [ $NOW_SEC -le $SAVED_SEC ] ; then
date -u -s "$SAVED"
else
echo "Current system time: $(date -u '+%Y-%m-%d %H:%M:%S')"
echo "fake-hwclock saved clock information is in the past: $SAVED"
echo "To set system time to this saved clock anyway, use \"force\""
fi
else
echo "Unable to read saved clock information: $FILE does not exist"
fi
fi
;;
*)
echo $0: Unknown command $COMMAND
exit 1
;;
esac
Reboot.
Now you should have right system time backed up by RTC.
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Question
IgorS
I have seen many tutorials about connecting real time clock hardware on Orange Pi and Raspberry Pi.
What i didn't like was removing of fake-hwclock service, because I want that RTC works when it is connected, and fake-hwclock when RTC is not connected.
Therefore, I changed /sbin/fake-hwclock script to work in this way.
So, here is how to do this, tested on OrangePi+2E, Armbian Ubuntu legacy kernel:
Purchase cheap DS3231 module on eBay (cca. $1) like this one:
http://www.ebay.com/itm/DS3231-AT24C32-IIC-Modul-High-Precision-Real-Time-Clock-Module-Arduino-New-/292041844936?hash=item43ff0ce8c8:g:d80AAOSwdGFYtsFP
Put battery in module.
Shutdown and powerof OPi and connect module:
Orange (i2c0 bus) RTC module (DS3231 RTC + 24C32 eeprom) 1 3.3V 2 VCC 3 PA12 (TWI0_SDA/DI_RX/PA_EINT12) 3 SDA 5 PA11 (TWI0_SCK/DI_TX/PA_EINT11) 4 SCL 9 GND 1 GNDPower up OPi
Install i2c-tools.
sudo apt install i2c-toolsType command:
i2cdetect -y 0You should see:
0 1 2 3 4 5 6 7 8 9 a b c d e f 00: -- -- -- -- -- -- -- -- -- -- -- -- -- 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 40: -- -- -- -- -- -- -- -- UU -- -- -- -- -- -- -- 50: -- -- -- -- -- -- -- 57 -- -- -- -- -- -- -- -- 60: -- -- -- -- -- -- -- -- 68 -- -- -- -- -- -- -- 70: -- -- -- -- -- -- -- --This means that module is connected properly and that we have DS3231 on address 0x68 and eeprom 24C32 on address 0x57.
Type:
sudo echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-0/new_device i2cdetect -y 0You should see:
0 1 2 3 4 5 6 7 8 9 a b c d e f 00: -- -- -- -- -- -- -- -- -- -- -- -- -- 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 40: -- -- -- -- -- -- -- -- UU -- -- -- -- -- -- -- 50: -- -- -- -- -- -- -- 57 -- -- -- -- -- -- -- -- 60: -- -- -- -- -- -- -- -- UU -- -- -- -- -- -- -- 70: -- -- -- -- -- -- -- --This means that system is now using our RTC. Also, now should exist new device /dev/rtc1
Be sure that your system time is right, and type:
sudo hwclock -w -f /dev/rtc1Now our RTC must have right time. Check with:
sudo hwclock -r -f /dev/rtc1If everithing was ok, copy /sbin/fake-hwclock to bacup (just in case)
sudo cp ~/programming/sh/fake_hwclock/sbin/fake-hwclock /sbin/fake-hwclockEdit /sbin/fake-hwclock and place this code in it:
!/bin/sh # # script: /sbin/fake-hwclock # Changed by I.S. to use RTC if it is connected # # # Trivial script to load/save current contents of the kernel clock # from/to a file. Helpful as a *bootstrap* clock on machines where # there isn't a useful RTC driver (e.g. on development boards). Using # NTP is still recommended on these machines to get to real time sync # once more of the system is up and running. # # Copyright 2012 Steve McIntyre <93sam@debian.org> # # License: GPLv2, see COPYING # Config variables # RTC is attached on bus... i2c_bus=0 eeprom_address="57" rtc_address="68" # Orange PI +2e have RTC, so our device will be: rtc_device="rtc1" # fake-hwclock is using cron.hourly to periodically save system clock cronfile="/etc/cron.hourly/fake-hwclock" # If you want to periodically synchronize rtc with system time, change this to true update_rtc_periodically=false # End of config variables # I don't know are all needed programs in PATH, # therefore I'll declare all mine echo="/bin/echo" i2cdetect="/usr/sbin/i2cdetect" grep="/bin/grep" awk="/usr/bin/awk" ln="/bin/ln" hwclock="/sbin/hwclock" readlink="/bin/readlink" progs="$echo $i2cdetect $grep $awk $ln $hwclock $readlink" check_external_progs(){ not_found="" prog="" for prog in ${progs} do if [ ! -e "$prog" ]; then not_found=$prog" "$not_found echo "Required program not found: $prog" fi done if [ "$not_found"x = ""x ] ; then progs_ok=true else progs_ok=false fi unset not_found unset prog } recreate_cronjob() { if [ ! -e "$1" ]; then cat << 'EOF' > "$1" #!/bin/sh # # Simple cron script - save the current clock periodically in case of # a power failure or other crash if (command -v fake-hwclock >/dev/null 2>&1) ; then fake-hwclock save fi EOF fi } is_rtc_connected(){ check_external_progs if $progs_ok; then list=$($i2cdetect -y "$i2c_bus") rtc=$(echo "$list" | $grep "60:" | $awk '{print $10}') eeprom=$(echo "$list" | $grep "50:" | $awk '{print $9}') if [ "$eeprom" -eq "$eeprom_address" ]; then case $rtc in "UU") t="/dev/$rtc_device" r=$($readlink -f /dev/rtc) if [ "$r"="$t" ]; then $echo "true" else $ln -sf /dev/$rtc_device /dev/rtc >/dev/null 2>&1 if [ "$r"="$t" ]; then $echo "true" else $echo "false" fi fi;; $rtc_address) $echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-0/new_device sleep 5 $ln -sf /dev/$rtc_device /dev/rtc >/dev/null 2>&1 t="/dev/$rtc_device" r=$($readlink -f /dev/rtc) if [ "$r"="$t" ]; then $echo "true" else $echo "false" fi;; *) $echo "false";; esac else $echo "false" fi else $echo "false" fi } # Is RTC installed? rtc_installed=$(is_rtc_connected) if $rtc_installed; then # We dont need periodically saving rm -f "$cronfile" >/dev/null 2>&1 else # Restore periodically saving recreate_cronjob "$cronfile" fi if [ "$FILE"x = ""x ] ; then FILE=/etc/fake-hwclock.data fi COMMAND=$1 if [ "$COMMAND"x = ""x ] ; then COMMAND="save" fi FORCE=false if [ "$2"x = "force"x ] ; then FORCE=true fi case $COMMAND in save) if $rtc_installed; then #$echo "RTC save" $hwclock -w if $update_rtc_periodically; then $echo "cronjob restore" recreate_cronjob "$cronfile" fi else if [ -e $FILE ] ; then SAVED="$(cat $FILE)" SAVED_SEC=$(date -u -d "$SAVED" '+%s') NOW_SEC=$(date -u '+%s') if $FORCE || [ $NOW_SEC -ge $SAVED_SEC ] ; then date -u '+%Y-%m-%d %H:%M:%S' > $FILE else echo "Current system time: $(date -u '+%Y-%m-%d %H:%M:%S')" echo "fake-hwclock saved clock information is in the future: $SAVED" echo "To force the saved system clock backwards anyway, use \"force\"" fi else date -u '+%Y-%m-%d %H:%M:%S' > $FILE fi fi ;; load) if $rtc_installed; then #$echo "RTC load" $hwclock -s else if [ -e $FILE ] ; then SAVED="$(cat $FILE)" SAVED_SEC=$(date -u -d "$SAVED" '+%s') NOW_SEC=$(date -u '+%s') if $FORCE || [ $NOW_SEC -le $SAVED_SEC ] ; then date -u -s "$SAVED" else echo "Current system time: $(date -u '+%Y-%m-%d %H:%M:%S')" echo "fake-hwclock saved clock information is in the past: $SAVED" echo "To set system time to this saved clock anyway, use \"force\"" fi else echo "Unable to read saved clock information: $FILE does not exist" fi fi ;; *) echo $0: Unknown command $COMMAND exit 1 ;; esacReboot.
Now you should have right system time backed up by RTC.
Edited by Tidoadded Spoiler
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