Autoreplicant π-box - installation guide

// page en cours / documentation in construction //

Autoreplicant is a program that scans all the files on the π-box, and transfer them by audio using minimodem, the packet transfer is routed to the audio output of the pibox, so you can choose to use stream, radio or line out, or all of them together. Another raspberry can use the reception script, listen to the audio, and will be able to duplicate the π-box on this new host.

Prerequisites : the installation requires two raspberry pis. One that transmits, and one that receives the packets, and a radio if you transmit through FM.

Step 1. Setup the transmitter node - on the π-box

The transmitter has to be set on a working π-box. If you need to build one, refer to the π-box documentation page.

Install minimodem

Then, connect in ssh to the π-box and install minimodem.

 $ sudo apt-get install minimodem

Set the script to scan the π-box and transmits the files to minimodem

Download the transmission scripts here !
transmission.zip

You can put the scripts either via ssh/scp, or copy them directly on the π-box sd card in the /home/pi/
or
create them with nano, and copy paste the content below :

The sending script is to be put at: /home/pi/

 $ cd /home/pi

Create the script that scans the files and send them to minimodem :

$ nano launchrepicate.sh

Copy the script:

#!/bin/bash
######################################################################
# find all files of the os and send 2 minimodem one by one           #
######################################################################
sleep 3
while true
do
        find / -type d \( -path /proc -o -path /sys -o -path /tmp \) -prune -o -exec ./minimodemTXaudio.sh {} +
done

Save and quit the file.

Transform launchrepicate.sh into an executable

sudo chmod +x /home/pi/launchrepicate.sh

Set the Minimodem script that transmit the file name and its content

Create the file called minimodemTXaudio.sh :

nano minimodemTXaudio.sh

then copy the following script : 

#!/bin/bash
##########################################################################
# minimodemTXaudio pass any type of document to binary and then to Pi audio internal out #
##########################################################################
echo $(basename "$1") |tee /dev/tty1 | minimodem -q -8 --tx --alsa=plughw:0,0 100
sleep 1
cat "$1" | pv -l -L 1 -q |tee /dev/tty1 | minimodem -q -8 --tx --alsa=plughw:0,0 200 
exit 0

Save and quit the file.

The command pv allow to read slowly the result of the cat command line by line, tee allow to show on screen - console /dev/tty1 (see which console is used who) and send it to minimodem at the same time

Transform minimodemTXaudio.sh into an executable

sudo chmod +x /home/pi/minimodemTXaudio.sh

Startup script

you have to modify the rc.local file

nano /etc/rc.local

then modify as follow

/usr/bin/python3 /home/pi/pibox_V2/go.py 2> /home/pi/pibox_V2/error_log.txt >/dev/null &

cd /home/pi/
./launchrepicate.sh &

exit 0

Set up the pibox sound parameters

you have to set up the pibox settings as follows

inputs (with or without internet):
line in

outputs
through a stream, line out, or radio, according to how you want to transmit the signal (over internet, locally on FM, or via a cable)

Connect the minijack cable

Connect the minijack cable from the native soundcard of the Raspberry pi (audio output included on the Pi) to the microphone input of the USB external sound card

Configure alsamixer

while connected to the pibox with ssh, type :

     $ alsamixer

You will have to put the minimodem sound to the maximum. It uses the native spound card of the raspberry pi.
Then check the pibox external sound card by raising the mic input to the maximum.

after this step the sound shall be audible on the sound medium you chose.
now time to configure the receiver, on you second pibox

Step 2. Setup the receiver Node

on the second Raspberry pi or computer

Get the script

download the scripts here!
reception_script.zip

Install minimodem

 $ sudo apt-get install minimodem

Setup for reception script

the TX reception script is to put in the directory /home

 $ cd /home

Create the file minimodemRXaudioTXT.sh :

nano minimodemRXaudioTXT.sh

Copy the script : 

#!/bin/bash
######################################################################
# minimodem2fm_rcv.sh receive sound for textfile_name and data       #
######################################################################

minimodem --rx 200 -q -8 --rx-one
#minimodem --rx 200 -8 --rx-one

while true
do
    echo -e "\n"
    minimodem --rx 100 -q -8 --rx-one
#    minimodem --rx 100 -8 --rx-one
#    name="$(cat /tmp/name_textfile.txt)"
    echo -e "\n"

#    minimodem --rx 200 -8 --rx-one
done 

while true
do
        echo -e "\n"
        minimodem --rx 100  -8 --rx-one > /tmp/name_textfile.txt
        echo -e "\n"
        minimodem --rx 200  -8 --rx-one > /tmp/name_textfile.txt 
done

Save and exit the file (ctrl-X)

Then transform the file in an executable:

sudo chmod +x /home/pi/minimodemRXaudioTXT.sh

Configure Zlsa mixer depending on your global set up (with radio ? through a stream ? )

     $ alsamixer

then store the alsamixer parameter

    $ alsactl store

Then connect the sound output of the sound source (computer, radio) to the input of the receiver
and test the script !

It shall work !

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