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Setting up a PI-Star MMDVM hotspot node with a Raspberry PI

 The first thing is to download the Pi-Star software from https://www.pistar.uk/downloads/, at time of writing the current version is Pi-Star_RPi_V4.1.5_21-Jun-2021.zip,but you should get the latest available. I used a Raspberry PI 3B but it is possible to use a PI Zero W or other model.

You should then use either Etcher, or the Raspberry Pi imager to copy the image to your SD card, which should be at least 4GB and Class 10 or better, I used a 16GB simply because they are available for little money these days.

Simply put the SD card into your PI and attach a monitor and keyboard via USB connection. The PI should boot with the usual rainbow screen, the default login is pi-star and the password raspberry. We will change these soon. To find out what IP address your pi is on type ifconfig and hit return. If you are connected via ethernet you will be able to type http://pi-star.local into a browser and access the dashboard as below -

This will redirect after 10 seconds and you will be presented with the configuration screen -



 

The first thing is to go to Host Configuration and ensure that MMDVMHost and Simplex mode are checked and apply the changes for this section.

Next in the MMDVMHost Configuration and select a mode, my radio is DMR so that is what I have selected. You should not set up more than two modes as at the end of each transmission the node will start to scan for each mode in turn, and you should certainly setup the modes one at a time or it will get very confusing. You may also set up an LED display if you have one attached, or do this later. Click apply.

 The general configuration allows you to change the hostname in case you have more than one node or device with a similar name. Enter your callsign and RadioID number from RadioID.net, you cannot use digital radio without it. You should also select a suitable frequency, my node is dual band. You can get your latitude and longitude either form QRZ.com or maps.google.com. Simply right click your address on the map and click to copy the latitude and longitude into a text editor and paste them into the form. Below this enter your town or city. If you wish to enter a locator square then visit https://levinecentral.com/ham/grid_square.php and enter your postcode or callsign.

If you click auto it will insert your QRZ page if it exists, or you can paste it or any website url in manually. You should then select the modem pcb type that you are using. It may take a few goes but most end in Raspberry Pi and they are similar. We are setting up a private node so I have selected that and I want ARS to be transmitted too, this is of course optional.


You will need to set your timezone and dashboard language then click apply.


DMR Configuration - there may be other modes if you have selected them

Important to set all of these marked in blue

You should select DMRGateway for your country and BM_2341_United_Kingdom, note: this is not a talk group, just a server ID. Enable the Brandmeister network or it will not work. I left the DMR+ settings as the defaults and selected Color Code 1, you may choose others if needed, apply the changes.

Mobile GPS Configuration - I left alone

Firewall Configuration 

I did enable the dashboard to be public, actually it was already public due to me setting up port forwarding on my router, refer to the documentation for your router and whatever port forwarding you may already have in place.

Wireless Configuration

I clicked Configure WIFI and entered my SSID and password. I had to login to the terminal and run ifconfig again to see the new IP address. But pi-star.local worked into my browser over WiFI just fine.

Radio Configuration

I set up a number of new channels for the Brandmeister groups I wanted including TG9990 Parrot so I could test the node and it worked fine. I then copied the channels and edited them got TG8, 9 91, 2350, 2351, 2352, etc. That is your personal preference, you won't need more than a dozen. Do not forget to set each channel to TS2 (Time slot2) as that is the only one available and the same color code as you selected above. ** I then found out is is better to have only one static group such as 2350 or TG8, 9, 10

Remote Access Password

Last of all you should change your remote access pass word to prevent intruders logging in.

Backup the configuration

Is is very useful  to be able to restore the configuration in an emergency or just to transfer it to another PI.


Save it to your pc and keep it safe, also useful for experimenting with different settings.

 

Testing the Pi Star Node

You may need to experiment with the location of your node for best WiFi reception (if not using ethernet) and make the most of the transmit power.  I suggest listening in to TG91 Worldwide, or turning Digital Monitoring on your radio and seeking a less busy group. You can then test how far you can receive the radio. When there is a gap in transmissions, press the PTT and check the dashboard sees your connection both at the top of the screen, and at the bottom where the RF connections are listed. You will see info regarding dropped packets and signal strength there too.

Extra Information

Having tested the configuration above I discovered that it does not access all talk groups automatically as there are too many. We need to register and login to the Brandmeister Dashboard at brandmeister.network/ and select 'My Hotspots' as below
 

Selec 'My Hotspots' and the digital Id, then add talk groups as needed for what you want to listen to



 These settings will automatically be linked to your node.

We can also enable DMR+ by going to http://phoenix-f.opendmr.net/ipsc/
 


If we select a DMR+ server as above 'DMR+_IPSC2-PhoenixF' and enter the options below like 'StartRef=4440;RelinkTime=15;UserLink=1;' where StartRef is the start Talk Group, RelinkTime is the hang time before a disconnect occurs, we can access more talk groups via Phoenix, see the lists at https://www.dmr-uk.net/index.php/hotspots/

Moving forwards
 
If you expereince errors, distortion or audio drop-outs then calibrate your MMDVM board by following this great article https://www.george-smart.co.uk/tag/mmdvmcal/. You will need to ssh or use Putty to login to the Pi-Start terminal. I did not need to change anything!



Static IP address configuration
 
I needed static IP addresses (or so I thought - see below), so I executed the following commands after logging in with Putty from Windows, you could of course SSH from Linux or Mac OS
 
(To get the ip address, login to the pi-star and type ifconfig )
 
login with pi-star and your password
 
rpi-rw 
cd /etc
 
sudo nano dhcpcd.conf

Now remove the '#' symbols and edit the ip addresses to suit your network, wlan0 is WiFi and eth0 is Ethernet (wired connection)

interface wlan0
static ip_address=192.168.178.100/24
static ip6_address=fd51:42f8:caae:d92e::ff/64
static routers=192.168.1.1
static domain_name_servers=192.168.178.1 8.8.8.8 fd51:42f8:caae:d92e::

# define static profile
profile static_eth0
static ip_address=192.168.178.100/24
static ip6_address=fd51:42f8:caae:d92e::ff/64
static routers=192.168.1.1
static domain_name_servers=192.168.178.1 8.8.8.8 fd51:42f8:caae:d92e::

sudo reboot

this should give you static IP addresses!
 
If you  have multiple routers like me then see this article https://forum.pistar.uk/viewtopic.php?p=14156#p14156
 
 


Let me know how you get on with your node. I have ordered a different OLED display as the 1.3" 7 pin one would not work. I'll try a 0.96 inch 4 pin one like everyone else. I also found the case used by many others for pre-built solutions!

Loads more info at https://www.pistar.uk/

 

 

 

 

 

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