Abstract

This is the repository for SALMO, the Solar Azimuth and eLevation Motorized lOcator.
SALMO is a PCB used for driving a tracking PV solar panel system, using only GPS location (and of course one magnetometer and one accelerometer to read the feedback of the panel position).

About the project

During the second semester of the 2021/2022 A.Y. of their bachelor degree in Electronics Engineering, a group of students known as SALMO SOCIETY, developed a custom board to solve real world problems.
Nowadays, we are all aware about climate change and it's impact, so the SALMO SOCIETY decided in partecipate to the renewable energy run, in particular exploiting the energy obtained by a solar panel to drive a load.
The aim of the board it's to move the solar panel using two step motors (along z-y axis) facilitating the MPPT (not implemented yet) and, as consequence, delivering the maximum power to the batteries.
Using a GPS module, the board knows exactly where it is located around the globe; afterwards the position of the sun is computed with a specific algorithm based on astronomical calculations. Then, the spatial position of the panel is derived by the accelerometer and compass modules; lastly, the motor is moved in order to follow the exact position of the sun (given its azimuth and elevation).

Project Features

The project has a lot of features, designed for an easy and pleasant user exeperience, such as:

• USB interface
• OLED Display (need firmware implementation)
• Buzzer and RGB led (need corrections) to indicate board status
• Current and Voltage sensing (need firmware implementation)
• Simple "Tracking Enable" and "Home" buttons
• Extreme expandability through the expansion connector (4 GPIO, 2 ADC input, I2C lines, +3.3V)

Repo structure

📂 SALMO_pico_fw    -> Firmware 
📂 datasheets       -> Datasheet of every component mounted on board
📂 kicad-project    -> KiCad and gerber files 

🌈 Building process

Debian:

sudo apt install cmake gcc-arm-none-eabi libnewlib-arm-none-eabi build-essential

Fedora:

sudo dnf install cmake
sudo dnf group install "C Development Tools and Libraries" "Development Tools"
sudo dnf install gcc-arm-linux-gnu \
arm-none-eabi-gcc-cs-c++ \
arm-none-eabi-gcc-cs \
arm-none-eabi-binutils \
arm-none-eabi-newlib

then:

git pull
git submodule update --init --recursive

now add to your shell profile (~/.bashrc or ~/.zshrc) the current directory (pico-sdk folder) as env variable:

export PICO_SDK_PATH=<path_to>/pico-sdk

Windows:

Follow this guide and you're good to go.

Finally, in order to compile:

cd SALMO_pico_fw
mkdir build
cd build 
cmake ..
cd src
make -j4

After this process some binaries files will be created.
The suitable one is the .uf2 file, which is located into SALMO_pico_fw/build/src.
Now you can start the board in bootloader mode:

1. Disconnect the board
2. Hold the BOOTSEL button
3. Connect the device to your computer

Then drag and drop the .uf2 file to RPI-RP2 mass storage device.

Picotool

If you want to install picotool and easily flash when RP2040 is not in BOOTSEL mode, you need to follow these steps:

Debian:

sudo apt install build-essential pkg-config libusb-1.0-0-dev

Fedora:

sudo dnf install libusb-devel libusb libusb1-devel systemd-devel
sudo reboot

Mac:

xcode-select --install
brew install libusb
brew link --overwrite libusb

Windows:

For now Picotool doesn't seem to work on Windows, skip these steps and flash "manually" moving the .uf2 file.

Compiling Picotool

After you have downloaded picotool you have to compile it:

cd picotool
mkdir build
cd build
cmake ..
make

Afterwards, you must give execution permissions to the scripts:

cd ../../SALMO_pico_fw/src
sudo chmod +x build.sh
sudo chmod +x flash.sh
sudo chmod +x build_and_flash.sh

If something on MacOS doesn't work use

sudo chown -R {username}:{workgroup} ppse-2021

Then, you can simply navigate to SALMO_pico_fw/src/ and execute build.sh, flash.sh or build_and_flash.sh to respectively build, flash or build and flash the project. 💅

Firmware flow chart

graph TB
A[Peripherals initialization] -->B(Infinite loop)
    B --> C{Is go home btn pressed?}
    C -->|Yes| D(Go home) --> E
    C -->|No| E{Is tracking enable btn pressed?}
	E -->|Yes| E1(Enable or disable tracking mode) --> F
	F{Is update_motor_position_timer elapsed <br>and tracking mode on?}
	F -->|Yes| G(Update motor position) --> H
	F -->|No| H{Is gps timer elapsed?}
	E -->|No| H
	H -->|Yes| I(Read and parse GPS output) --> L
	H -->|No| L{Is update sun position timer elapsed?}
	L -->|Yes| M(Run algorithm to compute sun position based on GPS data) --> B
	L -->|No| B

How to contribute to the project

In this sections you can find some guidelines in order in order to contribute with out project

Commits

A good commit message should be preceded by a prefix, then a colon and then a brief and descriptive comment on the changes made.
All commits should be written in the present simple tense (eg. add file, modify this, edit that).
Commits may also include longer descriptions in the second argument of a commit message.

Following are the prefix conventions for this repository.

• hw: for hardware (schematic, pcb, ...)
• fw: for firmware
• sw: for software (interfaces on a pc and such)
• docs: for documentation
• notes: for lecture notes
• chore: for general tasks (file management, moving stuff around, ...)

❌ git commit -m "Added some features to code"
✔️ git commit -m "fw: add uart implementation to gps driver"

File naming

All files must have no spaces and should be lowercase.

❌ Name of file.ext
✔️ name-of-file.ext

💼 Adding new drivers or libraries

If you want to add a new driver or library please keep this tree structure

📦 SALMO_pico_fw
 ┣📜 CMakeLists.txt (Project cmake file)
 ┣ 📂 build
 ┣ 📂 src
 ┗ 📜 CMakeLists.txt (SALMO.C cmake file)
 ┣ 📂 your_lib
 ┃ ┗ 📂 your_lib docs
 ┃ ┗ 📜 CMakeLists.txt (lib cmake file)
 ┃ ┗ 📜 your_lib.c.
 ┃ ┗ 📜 your_lib.h

Every library needs some sort of documentation, and of course a cmake file!