ams-han-port

Read HAN port on Norwegian AMS Smart Meters

This is a fork of https://github.com/per-erik-nordbo/ams-han-port, with added MQTT functionality. It is in a very early stage, but the MQTT sending works. Tested on a Raspberry Pi.

I cannot promise any development, as long as it works for me and nobody else asks for anything.

Main changes to the parent project:

New files

• han-reader.c reimplements the HAN-reading functionality from read.c, in a more reusable way
  • in the long run, the original serial-output code could be rewritten to use this
• han-mqtt.c implements the MQTT functionality
• han2mqtt.c is the main driver
  • currently a bare minimum, no command-line options etc.

Future possibilities

There are two main options:

• keep han2mqtt as a separate binary, with only MQTT functionality
• add the MQTT with the original binary, as one of possible outputs
  • note that this option would imply dependence on a MQTT library for all users

Independent on this, the MQTT part needs the following:

• some way of controlling the parameters: either command-line parameters, or a config file
• possibly a more "standard" format of the MQTT messages, for example using the Homie format

Dependencies

The code requires Mosquitto MQTT library. In Debian, this can be installed using apt install libmosquitto-dev.

Building han2mqtt

• Using the Makefile

  1. edit the SERIAL_PORT and MQTT_SERVER values in the han2mqtt line in the Makefile
  2. run make han2mqtt

• Direct gcc command:

  • run gcc -Wall -Wextra -O2 -D SERIAL_PORT='"<SERIAL_PORT>"' -D MQTT_SERVER='"<MQTT_SERVER>"' han2mqtt.c han-mqtt.c han-reader.c rs232.c aes.c -lmosquitto -lm -o han2mqtt
  • on Raspberry Pi with UART adapter, the SERIAL_PORT tends to be /dev/ttyUSB0
  • at the moment, the MQTT broker port is hard-coded in han2mqtt.c

Make it a services that starts on boot

This assumes a linux system with systemd (almost any modern linux).

• As a root (sudo), create /etc/systemd/system/ams-han.service with the following content:

   [Unit]
   Description=ams-han
   After=network.target
   
   [Service]
   ExecStart=/opt/ams-han/han2mqtt
   WorkingDirectory=/opt/ams-han
   StandardOutput=inherit
   StandardError=inherit
   Restart=always
   User=pi
   
   [Install]
   WantedBy=multi-user.target
  

  • replace /opt/ams-han by the path to the code and pi by your user name
  • make sure that the user has access to the folder

• Run sudo systemctl daemon-reload to refresh the service list

• Run sudo systemctl start ams-han.service

• Run sudo systemctl status ams-han.service to check everything is OK

• If everything looks OK, enable the service: sudo systemctl enable ams-han.service

At any later point, you can see the current output using journalctl -u ams-han -f