+++
title = 'DMRHost on a RaspberryPi 4 with OpenBSD'
summary = '''A rather quick demonstration of my recent test to install
    DMRHost on a Raspberry Pi 4 which is running OpenBSD 7.3'''
date = '2023-08-26T19:07:53+0200'
#lastmod = ''
categories = [ 'amateur-radio' ]
tags = [ 'hotspot', 'raspberry-pi', 'mmdvm', 'dmr', 'openbsd' ]

+++

## 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][0]

[0]: https://ftp.openbsd.org/pub/OpenBSD/snapshots/arm64/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).

```console
$ cu -l /dev/cuaU0 -s 115200
```

To save you another manpage lookup, exit the serial console
with <kbd>Enter</kbd>, <kbd>~.</kbd>.

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

1. Stop the autoboot process at the bootloader by typing something at
    the boot prompt (and delete the typed characters afterwards)

2. Plugin the SD-Card and hit <kbd>Enter</kbd>

3. The Installation media starts and detects your SD-Card

4. 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)

```aconf {linenos=inline,hl_lines="6"}
#
#	$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.

```console
$ 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.

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

Now, let's create the DMRHost executable.

```console
$ 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:

```ini
[...]

[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`.

```bash
#!/bin/sh
# rc-script for DMRHost on OpenBSD 7.3
# Dominic Reich <https://oe7drt.com>

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 -n "Starting DMRHost..."
    ${DOAS} ${DMRHOST} ${MMDVM_INI} &
    echo $! > ${DMRHOST_PID}
    echo " done"
  ;;

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

  "restart")
    $0 stop
    sleep 2
    $0 start
  ;;

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

esac
```

### First test / first start

Start DMRHost (not the service)

```console
$ 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 <kbd>CTRL</kbd>+<kbd>C</kbd>.

### Enable and start the service

```console
$ 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.