[arm-allstar] Adding a real-time clock (i2c etc) to arch Linux all Star?

[Tony Ross]

On 10/2/19 1:55 PM, "Kvo via ARM-allstar" wrote:
> I have attempted to ( quite unsuccessfully) add a hardware rtc (i2c) module to my raspberry pi running the Arch Linux image.
> Can someone guide me to the correct steps?

Since the GPIO pins are open on George's "Yellowbox", I decided to 
install http://amazon.com/gp/product/B01M105UFC which uses a DS3231 
clock chip. The included battery maintains time during power-off states, 
very useful for when Internet isn't available for "fakehwclock" 
synchronization at boot time, allowing a correct timestamp in the log files.

The following script worked perfectly for installation, and will most 
likely also install your RTC:


#!/usr/bin/env bash
#-----------------------------------------------------------
# Copyright (C) 2014-2016 GRUBERND http://grubernd.at
# released under a FreeBSD License
#-----------------------------------------------------------
# CATE installer module :: device RealTimeClock RPi
#
#???????????? !!?? needs to be run as root / sudo?? !!
#
# works both for DS1307 and DS3231 chips.
# this script is also designed to run standalone for
# both Arch Linux ARM and Raspbian installs.
#-----------------------------------------------------------
#_CATECONF__?????? # RTC service requires no configuration

if [[ "$(which pacman)" != "" ]]; then
 ?????? echo -e ""
 ?????? echo -e ".. installing I2C RTC for Arch Linux ARM"
 ?????? echo -e ""
 ?????? modules_file="/etc/modules-load.d/raspberrypi.conf"
 ?????? pacman -S --needed --noconfirm i2c-tools
fi

if [[ "$(which apt-get)" != "" ]]; then
 ?????? echo -e ""
 ?????? echo -e ".. installing I2C RTC for Raspbian"
 ?????? echo -e ""
 ?????? modules_file="/etc/modules"
 ?????? apt-get install --yes i2c-tools
fi

echo -e ""
echo -e ".. activating I2C devicetree in /boot/config.txt"

sed --in-place 
's/^#device_tree_param=i2c_arm=on/device_tree_param=i2c_arm=on/' 
"/boot/config.txt"

#-----------------------------------------------------------
echo -e ""
echo -e ".. adding i2c and rtc modules to the conf"

cp "$modules_file" /tmp/rtc.tmp
echo rtc-ds1307 >> /tmp/rtc.tmp
echo i2c-dev?????? >> /tmp/rtc.tmp
sort /tmp/rtc.tmp | uniq > "$modules_file"

#-----------------------------------------------------------
echo -e ""
echo -e ".. creating init script for the RTC"

mkdir -p /usr/lib/systemd/scripts/
cat > /usr/lib/systemd/scripts/rtc << ENDRTCSCRIPT
#!/bin/bash
# create an i2c device DS1307 (works also for DS3231)
# set systemclock from external i2c-rtc
echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-1/new_device
hwclock -s
ENDRTCSCRIPT

chmod 755 /usr/lib/systemd/scripts/rtc

echo -e ""
echo -e ".. creating service for the RTC"

cat > /etc/systemd/system/rtc.service << ENDRTCSERVICE
[Unit]
Description=RTClock
Before=network.target

[Service]
ExecStart=/usr/lib/systemd/scripts/rtc
Type=oneshot
[Install]
WantedBy=multi-user.target
ENDRTCSERVICE

#-----------------------------------------------------------
echo -e ""
echo -e ".. enabling and starting RTC service"

systemctl enable rtc
systemctl start rtc

#-----------------------------------------------------------
########## end script ##############