BallonSonde

BallonSonde Project 2023

This aim to group all ressources to create the PoC

Hardware requirements

• GNU/Linux Debian
• a RaspberryPi Zero 1.3 with nothing more (no WiFi, no BT)

Software requirement

For the RaspberryPi

apt update
apt upgrade
apt install bpython3 python3-venv python3-serial supervisor libopenjp2-7 screen imagemagick

# in user mode, setup PySSTV to convert pictures in wav mode
cd ~
mkdir PySSTV
python3 -m venv PySSTV/
cd PySSTV/
source bin/activate
pip install pysstv

Specs to do

Get the default shell

Should have a Serial interface on GPIO14(UART0_TXD) and GPIO15(UART0_RXD). I'm using a cheap FTDI232, from anywhere.

Enable secondary UART port

/!\ This step don't works, should not use it ! /!

Should add this config parameters to /boot/config.txt :

dtoverlay=disable-bt
dtoverlay=uart1,txd1_pin=32,rxd1_pin=33
force_turbo=1
enable_uart=1

Now we can use GPIO12 and GPIO13 for a secondary serial port

Switch the output soundcard to GPIOs

We have to play WAV files from the PySSTV converter, and put it directly in the microphone +/- input of the SA828 radio module.

By the way, we don't need stereo output, that's why I only made a single RC filter for filtering frequencies over 20Khz.

The configuration of /boot/config.txt will contain this line, then you can connect GPIO12 and GPIO13 to a stereo jack.

dtoverlay=audremap,pins_12_13 # for pins 12 and 13

Usages

chroot-to-pi.sh script

Use this script to chroot your system on another system.