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Updates and improvements on adding rtc boards

This commit is contained in:
KemoNine 2019-04-12 00:47:16 +01:00
parent fde8fb3287
commit 5d43882dd6
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1 changed files with 31 additions and 50 deletions
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hardware/rtc.md
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@ -35,15 +35,17 @@ armbian-config # enable i2c busses
systemctl reboot # reboot to enable bus(es)
apt install i2c-tools # install tools
i2cdetect -l # check to ensure busses are present
i2cdetect -y 0 # 0 for orange pi zero ; 1 for recent pi's
i2cdetect -y 1 # 0 for orange pi zero ; 1 for recent pi's
modprobe rtc-pcf8523 # load the proper rtc module (adafruit cheap model)
echo pcf8523 0x68 > /sys/class/i2c-adapter/i2c-0/new_device # setup device so it's seen
echo pcf8523 0x68 > /sys/class/i2c-adapter/i2c-1/new_device # setup device so it's seen
dmesg | grep rtc # verify the kernel sees the rtc
ls /dev/rtc* # should have rtc1
hwclock -r -f /dev/rtc1 # See if anything is on the rtc
hwclock -f /dev/rtc1 --systohc -D --noadjfile --utc # set / init the rtc
hwclock -r -f /dev/rtc1 # read the value from the rtc
hwclock -w -f /dev/rtc1 # write the current time to the rtc
apt remove --purge fake-hwclock # purge the fake hwclock as we have a real one now
systemctl disable fake-hwclock # Disable any dangling services
```
@ -58,50 +60,6 @@ EOF
```
## Internal RTC Adjustments
A systemd service to ensure the internal RTC is 'close' to the real time w/o battery.
``` bash
# Set the internal RTC on shutdown to match ntpified time
cat > /etc/systemd/system/rtc0-shutdown-fix.service <<EOF
[Unit]
Description=Set sunxi internal RTC on shutdown
DefaultDependencies=no
Before=shutdown.target reboot.target halt.target
[Service]
Type=oneshot
ExecStart=/sbin/hwclock --systohc -D --noadjfile --utc -f /dev/rtc0
[Install]
WantedBy=halt.target reboot.target shutdown.target
EOF
systemctl daemon-reload
systemctl enable rtc0-shutdown-fix
# Trick for getting the early boot time 'close'
cat > /etc/systemd/system/rtc0-online.service <<EOF
[Unit]
Description=Set system clock to rtc0
DefaultDependencies=no
Before=time-sync.target
[Service]
Type=oneshot
ExecStart=/sbin/hwclock -s -f /dev/rtc0
[Install]
WantedBy=time-sync.target
EOF
systemctl daemon-reload
systemctl enable rtc0-online
```
## External RTC On Boot
A systemd unit that brings the external RTC online during boot
@ -113,17 +71,15 @@ cat > /etc/systemd/system/rtc1-online.service <<EOF
Description=Setup rtc1 as primary clock
DefaultDependencies=no
Before=time-sync.target
After=rtc0-online.service
[Service]
Type=oneshot
ExecStart=/bin/sh -c '/sbin/modprobe rtc_pcf8523 \
&& echo pcf8523 0x68 > /sys/class/i2c-adapter/i2c-0/new_device \
ExecStart=/bin/sh -c '/sbin/modprobe rtc-pcf8523 \
&& echo pcf8523 0x68 > /sys/class/i2c-adapter/i2c-1/new_device \
&& /sbin/hwclock -s -f /dev/rtc1'
[Install]
WantedBy=time-sync.target
After=rtc0-online
EOF
systemctl daemon-reload
@ -131,6 +87,31 @@ systemctl enable rtc1-online
```
## Set RTC on shutdown
A systemd unit that sets the current time to the rtc on shutdown to minimize clock drift during next boot
``` bash
cat > /etc/systemd/system/rtc1-shutdown-fix.service <<EOF
[Unit]
Description=Set rtc1 on shutdown
DefaultDependencies=no
Before=shutdown.target reboot.target halt.target
[Service]
Type=oneshot
ExecStart=/sbin/hwclock --systohc -D --noadjfile --utc -f /dev/rtc1
[Install]
WantedBy=halt.target reboot.target shutdown.target
EOF
systemctl daemon-reload
systemctl enable rtc1-shutdown-fix
```
## Misc Notes
``` bash