JUno

Showcase

Showcase programs are complete, working applications built with Juno. Each one runs on real hardware, uses several parts of the API together, and is the best place to see how a larger program is organized. Their source is in juno-examples.

Mailbox

Mailbox is a remote messaging system for Claude. Run Mailbox and define an API key to be shared with Claude and the M5Stack Cardputer. On the M5Stack Cardputer you can send messages to Mailbox, and Claude periodically reviews the mailbox to process them and notify the status.

The M5Stack Cardputer ADV running the Mailbox client, its screen showing a message and the keyboard below it The Mailbox setup: a Java logo on one TFT shield, the mailbox screen on another with its message count and address, and the Cardputer below
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Sources usecases/mailbox
Board supported Arduino Q (server), M5Stack Cardputer (client)
Features used HTTPS server, HTTPS client, self-signed certificates, Wi-Fi, SD card, API key header, TFT touch screen, Cardputer keyboard, MVC view router, JSON, serial output, clock, delays

Gladiator

Gladiator is a game for the ELEGOO 2.8" TFT touch shield. Two gladiators fight in a Roman arena, each seen from its own board, while a third board keeps the arena. The solo mode runs a CPU-versus-CPU duel on a single board, with no network needed.

Gladiator Solo: the title, class selection, the versus view, then a CPU-versus-CPU bout until the result
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Sources games/gladiator
Board supported Arduino Q
Features used Wi-Fi, UDP, SD card, TFT touch screen, rotating 3D wireframe view, CPU opponent AI, lion, javelins, smoke, stamina, random numbers, clock

Doom

DOOM runs in landscape on the ELEGOO 2.8" TFT touch shield, drawn as a wireframe with DOOM's own BSP renderer. Pick HUMAN (touch to turn, walk and fire) or CPU (an autopilot), then the episode and skill. The game reads your own DOOM1.WAD from the microSD card.

DOOM on the TFT shield in the emulator: the CPU on I'm Too Young to Die clears E1M1 and E1M2 with the pistol, then picks up the shotgun on E1M3 and fights there until it dies
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Sources games/doom
Board supported Arduino Q
Features used TFT touch screen, SD card with RandomAccessFile, MVC view router, BSP wireframe renderer, CPU autopilot, serial output, delays, clock

Supabase

SupabaseGroveTemperatures reads three Grove temperature sensors once a minute and inserts them as one row of a Supabase table through its PostgREST API. It shows Wi-Fi, HTTPS requests with caller-owned buffers, and a timestamp taken once from LocalDateTime.now() and then advanced by the board's clock, so the program makes no extra time requests.

A failing sensor is sent as null, so one broken sensor does not stop the other two from being published. The board is a public client, so it uses a publishable key that is protected by Row Level Security. The UNO R4 WiFi page describes the wiring.

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Sources usecases/supabase
Board supported UNO R4 WiFi, UNO Q
Features used Wi-Fi, HTTPS, Grove sensors, Grove Base Shield, LocalDateTime, clock, TFT touch screen, MVC view router, serial output, delays

Lichess

LichessDailyChallenges is a chess tactics trainer for the UNO R4 WiFi and its TFT touch shield. The cover leads to a challenge menu built with the MVC pattern. The daily puzzle and a fresh public puzzle are fetched from Lichess as a position and its solution, and the player finds the moves on the touch board.

The program reads wifi.ssid and wifi.password from application.properties on the shield's microSD card. Its buffers are allocated once at startup, so the frame loop allocates nothing.

Lichess daily puzzle on the TFT shield: the board with the player's moves and Lichess's replies, then the win screen
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Sources usecases/lichess
Board supported UNO R4 WiFi
Features used Wi-Fi, HTTPS, JSON, SD card, TFT touch screen, MVC view router, chess piece rendering, clock, serial output, delays

Polyphonic RCX

ZeldaPolyphonicRcx plays the opening of Ocarina of Time as three synchronized instruments, one on each of the LEGO RCX bricks' channels one, two and three. The three bricks sound together, so the melody and its harmony come from different bricks.

The same program runs on an Arduino Nano ESP32 through the Nano Connector Carrier, in ZeldaPolyphonicRcxNano. Its infrared transmitter is on a Grove socket and its receiver on the Grove I2C socket. See the LEGO page for the RCX link. This version adds a bass instrument on a fourth brick, channel 4.

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Sources usecases/zeldapoliphonicrcx
Board supported Arduino Nano ESP32
Features used Infrared link, RCX channels, multi-brick playback, RCX indicator lights, Grove infrared emitter and receiver, Nano Connector Carrier, serial output, delays