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# Raspberry Pi Extension board # Raspberry Pi Extension Board
A custom PLC-like system based on the Raspberry Pi. A custom PLC-like system based on the Raspberry Pi.
With a custom interface board, a Raspberry Pi is extended with protected I/O, bus systems, analog inputs, and Relay or PWM outputs. All components, including a display, are housed in a custom-designed enclosure. With a custom interface board, a Raspberry Pi is extended with protected I/O, bus systems, analog inputs, and Relay or PWM outputs. All components, including a display, are housed in a custom-designed enclosure.
@ -9,7 +9,7 @@ The project is intended for versatile use in prototyping and project development
--- ---
### Photo of all hardware components ## Photo of All Hardware Components
<p align="center"> <p align="center">
<img src="doc/photos/all-components.jpg" alt="All Components (Disassembled)" width="75%"/> <img src="doc/photos/all-components.jpg" alt="All Components (Disassembled)" width="75%"/>
</p> </p>
@ -21,7 +21,7 @@ The project is intended for versatile use in prototyping and project development
# Repository Content # Repository Content
- **KiCad Projects**: 3 KiCad projects with schematics and PCB layouts for the custom PCBs created. - **KiCad Projects**: 3 KiCad projects with schematics and PCB layouts for the custom PCBs created.
- **Housing**: Custom enclosure design for PCBs and Raspberry Pi created in FreeCAD. - **Housing**: Custom enclosure design for PCBs and Raspberry Pi created in FreeCAD.
- **Software/Firmware**: Python scripts for operating and testing the PCB features (WIP). - **Software/Firmware**: Python scripts run on the Raspberry Pi for operating and testing the PCB features and providing examples as base for future projects.
--- ---
@ -42,7 +42,7 @@ Detailed features of each PCB are described in the respective sections below.
# Designed PCBs # Designed PCBs
## 1. **Raspberry Pi Interface Board** ## 1. Raspberry Pi Interface Board
This board connects to the Raspberry Pi via a 40-pin ribbon cable and provides protected GPIO extensions and versatile input/output features. This board connects to the Raspberry Pi via a 40-pin ribbon cable and provides protected GPIO extensions and versatile input/output features.
### Photo ### Photo
@ -51,7 +51,7 @@ This board connects to the Raspberry Pi via a 40-pin ribbon cable and provides p
### Features ### Features
**Inputs**: **Inputs**:
- **8x Digital Inputs**: - **8x Digital Inputs**:
- Wide continuous voltage range (-1.7 V to 120 V), idea: compatible with 3 V and 24 V devices. - Wide voltage range (-1.7 V to 120 V) → compatible with 3 V and 24 V devices.
- TVS diodes for ESD and spike protection. - TVS diodes for ESD and spike protection.
- Reverse polarity protection. - Reverse polarity protection.
- Isolated with optocouplers. - Isolated with optocouplers.
@ -74,7 +74,7 @@ This board connects to the Raspberry Pi via a 40-pin ribbon cable and provides p
- 8x digital outputs (via shift register): - 8x digital outputs (via shift register):
- Low-power (30 mA push-pull) and high-power (500 mA open-drain) outputs. - Low-power (30 mA push-pull) and high-power (500 mA open-drain) outputs.
- Buzzer and relays connected to channels 6-8, with enable/disable switches. - Buzzer and relays connected to channels 6-8, with enable/disable switches.
- Note: Outputs are **not short-circuit proof**. - **Note**: Outputs are **not short-circuit proof**.
**General**: **General**:
- WAGO spring-loaded terminals for easy wiring. - WAGO spring-loaded terminals for easy wiring.
@ -85,7 +85,7 @@ This board connects to the Raspberry Pi via a 40-pin ribbon cable and provides p
- UART (unprotected). - UART (unprotected).
- I2C (TVS diodes, 2.2 kΩ pull-ups). - I2C (TVS diodes, 2.2 kΩ pull-ups).
- SPI (unprotected). - SPI (unprotected).
Note: Either RS485 or UART can be used at the same time (select with jumpers). - **Note**: RS485 and UART cannot be used simultaneously (select via jumpers).
### Schematic and Layout ### Schematic and Layout
<p align="center"> <p align="center">
@ -160,70 +160,179 @@ Small PCBs with LEDs, resistors, and mounting holes for housing indicators.
</p> </p>
<br>
--- ---
<br>
# Software/Firmware # Raspberry Pi Usage
Python code for operating the extension PCBs (e.g., GPIO pins, shift registers, ADC, and bus communication). This section is a work in progress (WIP), and example scripts will be added as development continues.
# ======== WIP ========
# Python scripting
The pin assignment to the actual terminals are defined / mapped in
`rpi-scripts\interface_board_pins.py` so it should be included in any custom script created to easily reference the terminal numbers printed onto the project housing in the code. See examples in `rpi-scripts\examples`
TODO: make those files link to file but with text still the file path
# Usage Raspberry-PI
## Connectivity ## Connectivity
The Raspberry Pi can operate **standalone** with a connected keyboard, mouse, and HDMI monitor, or by using the integrated display in the housing.
### Establish LAN Connection (ethernet) However, for **development**, it is recommended to connect it to a network via **WiFi or LAN**, allowing easy remote access from a laptop. A direct **Ethernet connection** between the Raspberry Pi and a laptop is often the simplest method.
configure in command.txt in boot partition?
### Establish WIFI Connection ### LAN Connection (Ethernet)
- **Connection**: Connect cable directly between raspberry and PC
- **Configure the PC interface**: Set a static ip address e.g. `192.168.1.1/24`
Note: Optionally also enable network sharing to enable the RPI to use the internet connection the PC currently has.
- **Configure the Raspberry Interface**: Set a static ip address e.g. `192.168.1.100/24`
The Raspberry Pi can be configured for **Ethernet access** using different methods:
- **Boot Partition Configuration:** Modify `cmdline.txt` on the SD card.
- **GUI Setup:** Use the built-in network manager if a monitor is connected.
- **Command Line (`nmcli`)**: Configure networking via the terminal.
To check the assigned IP run:
```bash ```bash
s nmcli device wifi connect <SSID> password <password> ip a
# replace <SSID> and <password> with actual wifi
``` ```
### Connect via ssh ### WiFi Connection
```powershell Probably the **fastest and easiest** way to set up communication between the Raspberry Pi and a PC - while even maintaining internet access - is to **use a mobile phone as a WiFi hotspot**.
Simply **connect both the Raspberry Pi and the laptop** to the same hotspot.
To connect to a WiFi network, use:
```bash
nmcli device wifi connect <SSID> password <password>
```
Replace `<SSID>` and `<password>` with the actual credentials.
The Raspberry Pi will **automatically reconnect** after a reboot.
Once connected, you can check the assigned IP on the Raspberry Pi using:
```
ip a
```
### SSH Access
For remote terminal access, connect via SSH from a laptop:
```bash
ssh pi@192.168.1.100 ssh pi@192.168.1.100
``` ```
Replace the IP with the actual address of the Raspberry Pi.
### Connect via rdp ### Remote Desktop (RDP)
Open mstsc from windows start menu, and enter ip, user root and password. To control the Raspberry Pi’s **GUI remotely**, RDP is pre-configured.
Or use powershell:
#### Connect via Windows Remote Desktop:
- Open **Remote Desktop Connection (mstsc)**.
- Enter the Raspberry Pi’s IP address.
- **Login:**
- **User:** `root`
- **Password:** (configured during setup)
- **Note:** Logging in as `pi` may result in a black screen.
#### Alternatively, use PowerShell:
```powershell ```powershell
mstsc /v:192.168.1.100:3389 mstsc /v:192.168.1.100:3389
``` ```
Note: currently only user `root` works (using user pi results in blackscreen)
### Mount filesystem in windows ### Mount Raspberry Pi Filesystem in Windows (SAMBA)
You can mount /home/pi folder in windows natively using samba For convenient file access and editing (e.g., with **VS Code**), the Raspberry Pi’s `/home/pi` directory can be **mounted as a network drive** using Samba.
Run in powershell to mount it as network device X (replace ip with the current ip of rpi)
Find out ip with running `ip a` on the raspberry #### Steps:
1. Determine the Raspberry Pi’s IP address:
```bash
ip a
```
2. Mount the `/home/pi` directory in Windows:
```powershell ```powershell
net use X: \\192.168.1.100\pi /user:pi net use X: \\192.168.1.100\pi /user:pi
``` ```
Replace `192.168.1.100` with the actual IP address.
## Scripts **Note:**
Currently, only `/home/pi` is available for mounting. To share additional directories, edit the Samba configuration file:
### Autostart GUI
```bash ```bash
git/rpi-interface-board/rpi-scripts/gui% s cp gui-start.service /etc/systemd/system/ # add a new `[share]` section with the desired folder path and permissions.
sudo nano /etc/samba/smb.conf
# then restart samba
sudo systemctl restart smbd
``` ```
# ======== END WIP ========
<br>
--- ---
<br>
# Python Scripting
All **terminal-to-pin assignments** are mapped in [`interface_board_pins.py`](rpi-scripts/interface_board_pins.py), allowing easy reference to terminal numbers labeled on the housing.
Example scripts demonstrating I/O control can be found in [`rpi-scripts/examples`](rpi-scripts/examples).
---
## Scripts & Development
### Running Python Examples
Pre-written **Python scripts** to control I/O terminals are located in:
```
rpi-scripts/examples
```
To run an example, execute:
```bash
cd /home/pi/git/rpi-interface-board/rpi-scripts/examples/
python read_digital_inputs.py
```
### Starting a New Python Project with I/O Access
To create a custom Python project using the **interface board**, follow these steps:
1. **Copy the entire `rpi-scripts/` folder** to your new project directory.
2. **Remove unnecessary files**, keeping at least:
- `rpi-scripts/interface_board_libs/` → contains custom drivers.
- `rpi-scripts/interface_board_pins.py` → maps terminal numbers to GPIO/ADC channels.
3. **Start coding** by modifying an existing example in `examples/`.
---
## GUI Interface
A **Python GUI** is available for **real-time monitoring** and **control** of all I/O terminals for quick testing.
### Run the GUI
```bash
cd rpi-scripts/gui
python main.py
```
### Enable GUI Autostart on Boot
The GUI is configured to start automatically on boot in **fullscreen mode**. To modify this behavior:
#### Enable autostart:
```bash
sudo cp rpi-scripts/gui/gui-start.service /etc/systemd/system/
sudo systemctl enable gui-start.service
```
#### Disable autostart:
```bash
sudo systemctl disable gui-start.service
```
### GUI Screenshots
<p align="center">
<img src="doc/graphics/python-gui-control.png" width="80%" />
<img src="doc/graphics/python-gui-monitor.png" width="80%" />
</p>
<br>
---
<br>
# Housing # Housing
Custom-designed enclosure includes: Custom-designed enclosure includes:
- Ports for Raspberry Pi. - Cutouts for all Ports for Raspberry Pi.
- Banana sockets for power outputs. - Mounting screws for all pcbs and Raspberry
- Exposed screw terminals. - Fan mount + venting slots
- Openings for buttons and LEDs. - Cutouts for all external pcb terminals
- Mounts for all PCBs and wiring. - Cutout + mounting arms (M2.5) for Display
<img src="doc/graphics/3d-model_housing.png" width="80%" alt="3D Model"/> <img src="doc/graphics/3d-model_housing.png" width="80%" alt="3D Model"/>