PPISS — Pee Percentage of the International Space Station

A tiny desk gadget that shows real-time ISS waste-tank levels on a round LCD. Built with a Wemos D1 Mini (ESP8266) and a GC9A01 240×240 TFT, housed in a 3D-printed enclosure.

The data comes straight from NASA's public ISS Live telemetry feed via the Lightstreamer protocol.

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Features

• Live telemetry — polls NASA's Lightstreamer server for urine tank, waste water, and clean water percentages
• Page-cycling display — each tank gets its own screen, rotating every 5 seconds
• Multi-SSID WiFi — configure multiple networks in secrets.h; the device cycles through them automatically
• 3D-printable case — top and bottom STL files included

Hardware

Part	Notes
Wemos D1 Mini	ESP8266-based, any clone works
GC9A01 240×240 round TFT	SPI, 1.28″

Wiring

GC9A01 Pin	D1 Mini Pin	GPIO
CS	D8	GPIO15
DC	D3	GPIO0
MOSI	D7	GPIO13
SCLK	D5	GPIO14
RST	NC	Software reset
BL	VCC	Always on

Enclosure

The models/ folder contains the 3D-printable enclosure:

File	Description
PPISS.skp	Master SketchUp source file
PPISS_top.stl	Top half of the case
PPISS_bottom.stl	Bottom half of the case

Project Structure

├── platformio.ini          PlatformIO config (ESP8266 RTOS SDK)
├── models/                 3D-printable enclosure files
│   ├── PPISS.skp
│   ├── PPISS_top.stl
│   └── PPISS_bottom.stl
└── app/
    ├── main.cpp            Entry point — creates all FreeRTOS tasks
    └── src/
        ├── secrets.h           WiFi credentials (git-ignored)
        ├── secrets.h.example   Template for secrets.h
        ├── blink/              Heartbeat LED task
        ├── wifi/               WiFi station management (multi-SSID)
        ├── iss/                Lightstreamer client + telemetry data
        └── display/
            ├── ui.c            Page-cycling UI task
            ├── gfx.h           Drawing primitives
            ├── font.h          Bitmap font
            ├── driver/         GC9A01 SPI driver (bit-banged)
            └── icons/          Tank and WiFi status icons

Getting Started

Prerequisites

• PlatformIO (VS Code extension or CLI)

Setup

1. Clone the repo

   git clone https://github.com/Matp101/PPISS.git
   cd PPISS
   

2. Configure WiFi — copy the example and fill in your credentials:

   cp app/src/secrets.h.example app/src/secrets.h
   

   Edit secrets.h and add one or more SSIDs:

   static const wifi_cred_t WIFI_CREDS[] = {
       { "MyNetwork",     "MyPassword"     },
       { "BackupNetwork", "BackupPassword"  },
   };

3. Build & upload

   pio run -t upload -t monitor
   

Nix / NixOS

If you're on NixOS or have Nix with flakes enabled, you can build and develop without installing PlatformIO globally.

Build the firmware:

nix run .

The firmware is output to .pio/build/d1_mini/firmware.bin.

Upload to board:

nix run .#upload

Serial monitor:

nix run .#monitor

Interactive dev shell

nix develop

Then use PlatformIO commands directly:

pio run
pio run -t upload
pio device monitor

Telemetry Items

The device tracks these ISS parameters (defined in app/src/iss/iss.c):

Item ID	Label	Description
NODE3000005	Urine Tank	Urine tank fill percentage
NODE3000008	Waste Water Tank	Waste water tank fill percentage
NODE3000009	Clean Water Tank	Clean water tank fill percentage

To add more items, append to the g_telem[] array in iss.c.

License

This project is licensed under the MIT License.

Acknowledgements

• Inspired by pISSStream
• NASA ISS Live for the public telemetry data
• Lightstreamer for the streaming protocol