NextionDriver (for MMDVMHost)

The purpose of this program is to provide additional control for Nextion display layouts other than the MMDVMHost supplied layouts. It does this by sitting between MMDVMHost and the Nextion Display. This program takes the commands, sent by MMDVMHost and translates, changes, adds or removes these commands.

The program will have to read MMDVM.ini to know the Layout, so it can set the baudrate accordingly.

The program can take some commandline parameters, but it also is possible to set the configuration parameters in the MMDVM configuration file by adding an extra section [NextionDriver].

The NextionDriver program will change the commands as needed and adds extra info (i.e. temperature, TG's info, ...) and sends this to the Nextion display.

This program also checks the network interface regularly, and it will show the most recent IP address, so you can check if the IP address changed.

When the files 'groups.txt' and 'stripped.csv' are present, user and talkgroup names will be looked up and sent to the display.
NOTE1 : both files have to be sorted in ascending ID order !
NOTE2 : for the user data lookup to work, you MUST switch off the DMRID lookup of MMDVMHost (check README-examples in the Nextion subdirectory)

The program also has the ability of receiving commands from the Nextion display. This way, one can provide buttons on a layout and do something in the host when such a button is pressed. One could, for example, make a 'system' page on the Nextion with system info and buttons to restart MMDVMHost, reboot or poweroff the host, ...

Yes, it is possible (when NextionDriver is running) to start/stop/restart MMDVMHost with buttons on the Nextion display !

How to use this program ?

Pi-Star users : check my website on7lds.net

after compiling with
make

you should have a binary
NextionDriver

You can start this program in debug mode, then all commands that are sent to the display, will be printed to stdout. Or you can start this program in normal mode, then it will go to the background and do its work quietly (start and stop of the program will be logged in syslog)

The most practical way to start is by specifying only one parameter: the place of the MMDVMHost configuration file. This way, all configuration can be done in the ini file.

./NextionDriver -c /etc/MMDVM.ini

will start NextionDriver from the current directory and read all parameters from the MMDVMHost ini file.

You can get the necessary changes in your MMDVMHost configuration file by executing the patch script

./NextionDriver_ConvertConfig

Then the script will make a backup of your current config and do the changes for you.

In case you want to do it by hand : In your MMDVMHost configuration file (mostly MMDVM.ini), make a section as below:

[NextionDriver]
Port=/dev/ttyAMA0
LogLevel=2
DataFilesPath=/opt/NextionDriver/
GroupsFile=groups.txt
DMRidFile=stripped.csv

IMPORTANT In the MMDVM.ini [Nextion] section you have to specify the NextionDriver's virtual port as the port to connect to :

[Nextion]
Port=/dev/ttyNextionDriver
...

to tell MMDVMHost to talk to our program an not directly to the display !

How to autostart this program ?

when systemd is used : (files are found in /etc/systemd/system being links to the real files in /lib/systemd/system/ )

First you alter mmdvmhost.service by adding the 'BindsTo' line This will tell the service it needs nextion-helper.service before starting MMDVMHost

mmdvmhost.service

[Unit]
Description=MMDVM Host Service
After=syslog.target network.target
BindsTo=nextion-helper.service

[Service]
User=root
WorkingDirectory=/opt/MMDVMHost
ExecStartPre=/bin/sleep 3
ExecStart=/usr/bin/screen -S MMDVMHost -D -m /opt/MMDVMHost/MMDVMHost /opt/MMDVM.ini
ExecStop=/usr/bin/screen -S MMDVMHost -X quit

[Install]
WantedBy=multi-user.target

Then you make a service 'nextion-helper.service' where you tell it needs to start before MMDVMHost :

nextion-helper.service

[Unit]
Description=Nextion Helper Service Service
After=syslog.target network.target
Before= mmdvmhost.service

[Service]
User=root
WorkingDirectory=/opt/MMDVMHost
Type=forking
ExecStart=/opt/NextionDriver/NextionDriver -c /opt/MMDVM.ini
ExecStop=/usr/bin/killall NextionDriver

[Install]
WantedBy=multi-user.target

How to change this program to your needs ?

The program has a lot of functions included, but those who want to add even more could do so. There are 2 files you could change :

Data to the Nextion Display

the routine process() in processCommands.c

• this routine is called for each command, sent by MMDVMHost. The command which is sent, is in RXbuffer (without the trailing 0xFF 0xFF 0xFF).
• the RXbuffer holds a string, so it is not possible to send 0x00 characters
• you can inspect, change or add commands, but keep in mind that at the end of the routine the RXbuffer (if not empty) is sent to the Nextion display (empty the buffer if you do not want to send something to the display)

Data from the Nextion Display

the routine processButtons() in processButtons.c

• This routine is called whenever there is an event sent from the display. For this you have to make a button on the Nextion display which has in its Touch Release Event following code:
  printh 2A
  printh (code nr)
  printh FF
  printh FF
  printh FF

where (code nr) is a number 0x01...0xEF (look sharp: 0xEF NOT 0xFF !) The command is in the RXbuffer (without the trailing 0xFF 0xFF 0xFF).

Then there are some special codes :

• when there is a command
  printh 2A
  printh F0
  printh (linux command)
  printh FF
  printh FF
  printh FF

the 'linux command' is executed

• When there is a command
  printh 2A
  printh F1
  printh (linux command)
  printh FF
  printh FF
  printh FF

the 'linux command' is executed and the FIRST line of the result is sent to the display variable 'msg'

There is an example HMI file included.
Press on the MMDVM logo on the main screen to go to the 'system' page