dominic

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vim: ft=markdown

title = 'DMRHost on OpenBSD on a Raspberry-Pi 4' summary = '' date = '2023-08-20T08:24:04+02:00' lastmod = '2023-08-20T09:15:14+0000' categories = [ 'amateur-radio' ] tags = [ 'hotspot', 'raspberry-pi', 'openbsd' ]

draft = true

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Get the files

Download install73.img from https://www.openbsd.org/arm64.html and write it to a USB stick.

Installation of OpenBSD

Get yourself comfortable with this nice piece of documentation: INSTALL.arm64

Connect a USB-to-TTL cable to the GPIO pins of the serial console on your Raspberry Pi (That means you have to remove the MMDVM hat for now).

$ cu -l /dev/cuaU0 -s 115200

To save you another manpage lookup, exit the serial console with Enter, ~..

Boot the Raspberry Pi with no SD-Card plugged in but the USB stick.

Stop the autoboot process at the bootloader by typing something at the boot prompt (and delete the typed characters afterwards)
Plugin the SD-Card and hit Enter
The Installation media starts and detects your SD-Card
Continue with the installation of OpenBSD

We booted without SD-Card because I had problems selecting the USB media for booting. You can select this from within Raspbian OS but I did not want to install this in the first place.

System configuration

Make sure to enable ssh. We will need that because we have to drop support for the serial console to use the MMDVM hat.

Disable the use of the serial console

Modify /etc/ttys (only the first lines are relevant)

#
#	$OpenBSD: ttys,v 1.2 2020/03/13 13:14:40 patrick Exp $
#
# name	getty				type	status		comments
#
console	"/usr/libexec/getty std.115200"	vt220	off secure
ttyC0	"/usr/libexec/getty std.9600"	vt220	off secure
ttyC1	"/usr/libexec/getty std.9600"	vt220	on  secure
ttyC2	"/usr/libexec/getty std.9600"	vt220	on  secure

Change on to off. Now select the framebuffer device for your tty.

$ echo "set tty fb0" | doas tee /etc/boot.conf

Once you made sure that you can login via ssh, turn off the Raspberry Pi and put on the MMDVM hat.

Now you should be able to select /dev/cua00 as the modem in your MMDVM.ini.

Setup DMRHost

Installation

Get the files: https://github.com/BrandMeister/DMRHost.

I prefer to use a separate user for this.

$ doas useradd -L daemon -G dialer,users -m -d /home/mmdvm -s /sbin/nologin -c "Radio &" mmdvm

Now, let's create the DMRHost executable.

$ cd /home/mmdvm
$ doas -u mmdvm (mkdir git && cd git)
$ doas -u mmdvm (git clone https://github.com/BrandMeister/DMRHost && cd DMRHost)
$ doas -u mmdvm (mkdir build && cd build && cmake -DCMAKE_BUILD_TYPE=Release ..)
$ doas -u mmdvm make && doas make install

Note: the last command is not executed as the user mmdvm but as root as it is installing the executable into /usr/local/bin. Therefore we dropped the -u mmdvm on the last doas invocation!

Configuration of DMRHost: `MMDVM.ini`

I use /home/mmdvm/MMDVM.ini because I'll put everything MMDVM-related into /home/mmdvm.

The essential congiguration changes:

[...]

[Log]
# Logging levels, 0=No logging, 1=Debug, 2=Message, 3=Info, 4=Warning, 5=Error, 6=Fatal
SyslogLevel=0
DisplayLevel=0
FileLevel=2
FilePath=/home/mmdvm/logs
FileRoot=DMRHost
FileRotate=0

[...]

[Modem]
Port=/dev/cua00
Protocol=uart

[...]

This is basically the same configuration as in the repository. Have a look at the [Log] section.

The rc script `/etc/rc.d/DMRHost`.

#!/bin/sh

DMRHOST="/usr/local/bin/DMRHost"
MMDVM_INI="/home/mmdvm/MMDVM.ini"
DMRHOST_PID="/home/mmdvm/DMRHost.pid"
DOAS="/usr/bin/doas -u mmdvm"
LOGDIR="/home/mmdvm/logs"

case "$1" in
  "start")
    if [ ! -d ${LOGDIR} ] ; then
      mkdir ${LOGDIR}
      chown mmdvm:users ${LOGDIR}
      chmod 0775 ${LOGDIR}
    fi
    if ${DOAS} [ ! -r ${MMDVM_INI} ] ; then
      echo "${MMDVM_INI} is not readable... aborting!"
      exit 1
    fi
    echo "Starting DMRHost..."
    ${DOAS} ${DMRHOST} ${MMDVM_INI} &
    echo $! > ${DMRHOST_PID}
    echo "done"
  ;;

  "stop")
    echo "Stopping DMRHost..."
    if [ -f ${DMRHOST_PID} ] ; then
      kill `cat ${DMRHOST_PID}`
      rm -f ${DMRHOST_PID}
      echo "done"
    else
      echo "not running?"
    fi
  ;;

  "restart")
    echo "Restarting DMRHost..."
    $0 stop
    sleep 2
    $0 start
  ;;

  *)
    echo "$0 [start|stop|restart]"
  ;;

esac

First test / first start

Start DMRHost (not the service)

$ doas -u mmdvm /usr/local/bin/DMRHost /home/mmdvm/MMDVM.ini

and see what it does. If it's logging into the master, all is good and can be stopped with CTRL+C.

Enable and start the service

$ doas rcctl enable DMRHost
$ doas rcctl start DMRHost

DMRHost runs.

Some additional notes

I put myself (another user on the Raspberry Pi) into the users group and chmod the MMDVM.ini with with 664.

That allows me to edit the file as my usual user and I do not have to use doas -u mmdvm everytime I want to modify something in that file.

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