This program uses Arduino. If you'd just like to run the program without using Arduino, you can download the .UF2 file below in the green box. Save the file to your computer. Plug the Metro RP2350 into your computer with a known good USB cable (data + power, not a charge only cable).
Hold down the BOOT/BOOTSEL button (highlighted in red above), and while continuing to hold it (don't let go!), press and release the reset button (highlighted in blue above). Continue to hold the BOOT/BOOTSEL button until the RP2350 drive appears on your computer! Copy the .UF2 file you saved previously to the RP2350 drive and The Matrix should appear if you have the display connected.
Arduino
Please refer to the Arduino IDE setup in the Adafruit Metro RP2350 guide.
You will want to add the library Adafruit DVI HSTX (version 1.10 or later, likely the latest version) to your Arduino environment. Select Sketch - > Include Library -> Manage Libraries... Search for "Adafruit DVI HSTX" by Jeff Epler. You will want version 1.1.0 or later, likely the newest version. Click Install and accept installing libraries that Adafruit DVI HSTX is dependent on. Those are the only libraries which need to be loaded.
For the main program, get the code by clicking the "Download Project Bundle" button below. Extract the file Metro_HSTX_Matrix.ino from the zip archive. Load it into the Arduino IDE.
// SPDX-FileCopyrightText: 2021 Anne Barela for Adafruit Industries
//
// SPDX-License-Identifier: MIT
//
// Based on Adafruit-DVI-HSTX library code written by Jeff Epler
// and use of Claude 3.7 Sonnet on 3/2/2025
// https://claude.site/artifacts/cf022b66-50c3-43eb-b334-17fbf0ed791c
#include <Adafruit_dvhstx.h>
// Display configuration for text mode in Adafruit-DVI-HSTX
const int SCREEN_WIDTH = 91;
const int SCREEN_HEIGHT = 30;
// Animation speed (lower = faster)
// Adjust this value to change the speed of the animation
const int ANIMATION_SPEED = 70; // milliseconds between updates
// Initialize display for Adafruit Metro RP2350
DVHSTXText display({14, 18, 16, 12}); // Adafruit Metro HSTX Pinout
// Define structures for character streams
struct CharStream {
int x; // X position
int y; // Y position (head of the stream)
int length; // Length of the stream
int speed; // How many frames to wait before moving
int countdown; // Counter for movement
bool active; // Whether this stream is currently active
char chars[30]; // Characters in the stream
};
// Array of character streams - increased for higher density
// To fill 60-75% of the screen width (91 chars), we need around 55-68 active streams
CharStream streams[250]; // Allow for decent density
// Stream creation rate (higher = more frequent new streams)
const int STREAM_CREATION_CHANCE = 65; // % chance per frame to create new stream
// Initial streams to create at startup
const int INITIAL_STREAMS = 30;
// Random characters that appear in the streams
const char matrixChars[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!@#$%^&*()-_=+[]{}|;:,.<>?/\\";
const int numMatrixChars = sizeof(matrixChars) - 1;
// Function declarations
void initStreams();
void updateStreams();
void drawStream(CharStream &stream);
void createNewStream();
char getRandomChar();
void setup() {
// Initialize the display
display.begin();
display.clear();
// Seed the random number generator
randomSeed(analogRead(A0));
// Initialize all streams
initStreams();
}
void loop() {
// Update and draw all streams
updateStreams();
// Randomly create new streams at a higher rate
if (random(100) < STREAM_CREATION_CHANCE) {
createNewStream();
}
// Control animation speed
delay(ANIMATION_SPEED);
}
void initStreams() {
// Initialize all streams as inactive
for (int i = 0; i < sizeof(streams) / sizeof(streams[0]); i++) {
streams[i].active = false;
}
// Create more initial streams for immediate visual impact
for (int i = 0; i < INITIAL_STREAMS; i++) {
createNewStream();
}
}
void createNewStream() {
// Find an inactive stream
for (int i = 0; i < sizeof(streams) / sizeof(streams[0]); i++) {
if (!streams[i].active) {
// Initialize the stream
streams[i].x = random(SCREEN_WIDTH);
streams[i].y = random(5) - 5; // Start above the screen
streams[i].length = random(5, 20);
streams[i].speed = random(1, 4);
streams[i].countdown = streams[i].speed;
streams[i].active = true;
// Fill with random characters
for (int j = 0; j < streams[i].length; j++) {
streams[i].chars[j] = getRandomChar();
}
return;
}
}
}
void updateStreams() {
display.clear();
// Count active streams (for debugging if needed)
int activeCount = 0;
for (int i = 0; i < sizeof(streams) / sizeof(streams[0]); i++) {
if (streams[i].active) {
activeCount++;
streams[i].countdown--;
// Time to move the stream down
if (streams[i].countdown <= 0) {
streams[i].y++;
streams[i].countdown = streams[i].speed;
// Change a random character in the stream
int randomIndex = random(streams[i].length);
streams[i].chars[randomIndex] = getRandomChar();
}
// Draw the stream
drawStream(streams[i]);
// Check if the stream has moved completely off the screen
if (streams[i].y - streams[i].length > SCREEN_HEIGHT) {
streams[i].active = false;
}
}
}
}
void drawStream(CharStream &stream) {
for (int i = 0; i < stream.length; i++) {
int y = stream.y - i;
// Only draw if the character is on screen
if (y >= 0 && y < SCREEN_HEIGHT) {
display.setCursor(stream.x, y);
// Set different colors/intensities based on position in the stream
if (i == 0) {
// Head of the stream is white (brightest)
display.setColor(TextColor::TEXT_WHITE, TextColor::BG_BLACK, TextColor::ATTR_NORMAL_INTEN);
} else if (i < 3) {
// First few characters are bright green
display.setColor(TextColor::TEXT_GREEN, TextColor::BG_BLACK, TextColor::ATTR_NORMAL_INTEN);
} else if (i < 6) {
// Next few are medium green
display.setColor(TextColor::TEXT_GREEN, TextColor::BG_BLACK, TextColor::ATTR_LOW_INTEN);
} else {
// The rest are dim green
display.setColor(TextColor::TEXT_GREEN, TextColor::BG_BLACK, TextColor::ATTR_V_LOW_INTEN);
}
// Draw the character
display.write(stream.chars[i]);
}
}
// Occasionally change a character in the stream
if (random(100) < 25) { // 25% chance
int idx = random(stream.length);
stream.chars[idx] = getRandomChar();
}
}
char getRandomChar() {
return matrixChars[random(numMatrixChars)];
}
Select Adafruit Metro RP2350 as the board in the box in the toolbar.
Plug your Metro into your computer via a known good USB data + power cable (not the tiny power-only cables that come with battery packs). The Metro should show up as a new serial port. Select that serial port under Tools -> Port.
Click the arrow key -> on the toolbar to compile the program and upload it to the Metro.
Changing the Code
You can change how many streams are on the screen at the same time by changing the STREAM_CREATION_CHANCE variable. It should be from 10 (lowest) to 99 (highest).
Using Pico 2 instead of Metro RP2350
The HSTX pins for Metro RP2350 are defined as:
DVHSTXText display({14, 18, 16, 12});
But for other boards you may need to use
DVHSTXText display({12, 14, 16, 18});
It's all depending how you wired your HSTX bus - the wire pairs can be swapped IF your code knows it. It would help if the Pico 2 had an HSTX connector on top. Oh well.
Page last edited March 06, 2025
Text editor powered by tinymce.
