piupsmonitor

Program to monitor the PiUPS+ (PiUSV+) module for the raspberry pi.

This program is a replacement for the original piupsmon which lacks the availability of source code.

I tried to use the original init.d script, but that does not work, due to the fact, that the Raspian Os now uses systemd. The PiUSV+ won't power off because the variable RUNLEVEL ist not set during shutdown causing the poweroff timer not to be set.

So I created two systemd-services, one to start the daemon in multi-user.target and another to programm the poweroff timer on shutdown. By replacing the /usr/sbin/piupsmonitor with /usr/bin/piupsmon the service might even work with the original piupsmon.

Reqirements

Hardware

• Raspberry Pi
• PiUSV+

Software

• libi2c-dev # Library for C

Use the following command to install the library:

sudo apt install libi2c-dev

Configure

Enable I2C

sudo raspi-config

Go to "3 Interface Options" -> "I5 I2C" -> select Yes and reboot.

Install

Compile piusvmonitor.c

mkdir -p usr/sbin
gcc -O -o usr/sbin/piupsmonitor src/piupsmonitor.c -li2c

Install config file

sudo cp -a etc/piupsmonitor /etc

The configuration can be changed in /etc/piupsmonitor/piupsmonitor.conf

Install binary

Copy the binary

sudo cp -a usr/sbin/piupsmonitor /usr/sbin

Copy the systemd service files if you want to start piupsmonitor during boot

sudo cp -a etc/systemd/system/piupsmonitor*.service /etc/systemd/system/

and enable the services

sudo systemctl daemon-reload
sudo systemctl enable piupsmonitor.service
sudo systemctl start piupsmonitor.service
sudo systemctl enable piupsmonitor-poweroff.service

Don't start the piupsmonitor-poweroff.service or your Raspberry will poweroff whithout shutting down. The service will be started during shutdown to switch off the power after a delay (default 15 seconds).

Problems

i2c speed problems

On my Raspberry Pis I get Remote I/O error (121) if I use the default i2c baudrate. So I reduced it to 40000 and got no errors anymor.

Add the following to /boot/config.txt

dtparam=i2c_baudrate=40000

and reboot.

This problem is probably caused by the Raspberry Pi I2C clock-stretching bug. For more details s. e.g. here or ask Google.

By the way the problem exists with the original piupsmon, too. There I get occasionaly power failures in the logfile. With lowering the i2c baudrate they are gone.