ASL-Display: AllStarLink Display Driver

A Python display driver for Raspberry Pi with an Adafruit Mini PiTFT (ST7789 240×240). Shows IP, uptime, connected nodes, and a favourites menu, with two-button navigation for connecting and disconnecting AllStarLink nodes.

NEW: Simple install instructions on my website https://g1lro.uk/?p=848

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✨ What's New in v1.75

This release is a major performance rewrite focused on UI responsiveness.

Background display thread

The SPI transfer to the screen (~38ms per frame) previously blocked everything — buttons felt sluggish because the loop couldn't read input while the screen was updating. The display now renders in a dedicated background thread. Button presses register instantly regardless of what the screen is doing.

Non-blocking connect / disconnect

Pressing Button B to connect or disconnect a node used to freeze the display for 1–3 seconds while waiting for Asterisk. It now shows "Connecting NodeName..." or "Disconnecting 12345..." immediately, and the Asterisk command runs in the background. The screen updates again as soon as it completes.

Faster button polling

The main loop runs at 50 Hz (20 ms sleep) instead of the previous effective rate, so button presses are detected up to 5× faster.

Smart display updates

The display now only refreshes when something actually changes — on a button press, or every 5 seconds for the periodic data refresh. Previously it refreshed every second unconditionally.

No more subprocess for IP / uptime

IP address and uptime are now read using native Python (socket, /proc/uptime) instead of spawning shell subprocesses. This removes two process launches per second from the old code.

New features

• Node name lookup — connected nodes are looked up in astdb.txt for their callsign, falling back to favourites labels or "Node".
• Total linked node count — displayed at the bottom of the main screen.
• Safe shutdown — hold both buttons for 2 seconds to initiate a clean shutdown -h now with an on-screen message.

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Features

• Real-time display: IP address, uptime, connected AllStarLink nodes (up to 3), favourites menu (up to 6 nodes).
• Button controls:
  • Button A — cycle through selections.
  • Button B — connect / disconnect nodes, enter favourites mode, or exit.
  • Both buttons held 2 s — safe shutdown.
• Automatic updates: display refreshes on button press or every 5 seconds.
• Favourites: load node names and numbers from ~/favourites.txt.

Hardware Requirements

• Raspberry Pi (tested on Raspberry Pi OS, Debian-based).
• Adafruit Mini PiTFT or equivalent ST7789-based 240×240 display.
• Also available from AliExpress
• Wiring (standard on this model):
  • CS: GPIO CE0 (pin 24)
  • DC: GPIO D25 (pin 22)
  • Backlight: GPIO D22 (pin 15)
  • Reset: not connected
  • SPI: MOSI (pin 19), SCLK (pin 23)
• Buttons: GPIO D23 (pin 16) = Button A, GPIO D24 (pin 18) = Button B.
• AllStarLink / Asterisk installed and running.

Software Requirements

• Python 3
• Raspberry Pi OS or similar (Debian-based)
• AllStarLink with Asterisk
• SPI interface enabled (handled by the install script)

Installation

1. Clone the repository:

   sudo apt update
   sudo apt install git
   git clone https://github.com/G1LRO/ASL-Display.git
   cd ASL-Display
   

2. Make the install script executable and run it:

   chmod +x installdisplay.sh
   ./installdisplay.sh
   

   The script installs dependencies, creates a virtual environment, enables SPI, and sets up a systemd service.

3. Edit your favourites file (~/favourites.txt):

   58175        ← your node number on line 1
   Hubnet,41223
   FreeSTAR,63061
   

4. Reboot:

   sudo reboot
   

Configuration

• Node number: first line of ~/favourites.txt.
• Favourites: subsequent lines in Name,NodeNumber format, up to 6 entries.
• Version: edit VERSION = "1.75" near the top of display_driver.py.

Service management

sudo systemctl status display_driver.service
sudo systemctl restart display_driver.service
sudo systemctl stop display_driver.service
journalctl -u display_driver.service -b

Troubleshooting

• Blank display: check SPI (lsmod | grep spi_bcm2835) and service logs.
• Asterisk errors: test with sudo asterisk -rx "rpt lstats <node>".
• Font missing: check /usr/share/fonts/truetype/dejavu/DejaVuSans.ttf exists.
• Quick hardware test (save as test_display.py):

  #!/usr/bin/env python3
  import digitalio, board
  from adafruit_rgb_display import st7789
  from PIL import Image, ImageDraw
  cs_pin = digitalio.DigitalInOut(board.CE0)
  dc_pin = digitalio.DigitalInOut(board.D25)
  spi = board.SPI()
  disp = st7789.ST7789(spi, cs=cs_pin, dc=dc_pin, rst=None,
                       baudrate=24000000, width=240, height=240,
                       x_offset=0, y_offset=80)
  image = Image.new("RGB", (240, 240))
  draw = ImageDraw.Draw(image)
  draw.rectangle((0, 0, 240, 240), fill=(255, 0, 0))
  disp.image(image, 180)

  A red screen confirms hardware is wired correctly.

License

Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0). Portions based on Adafruit code are under MIT. Retain all copyright notices in modifications or distributions.

Credits

• Inspired by Adafruit's RGB display examples.
• Developed by G1LRO for non-commercial ham radio use.
• Website: g1lro.uk

Contributions welcome — open an issue or submit a pull request.