How to display a number on the UNO Q's built-in LED matrix, please?

petersin · December 19, 2025, 1:33pm

Please, how to display numbers on .. Uno Q built in LED MatriX? i found the code for strings. but i cant convert it into numbers.

// ---- UNO Q LED Matrix text scroller (8x13), using only matrixBegin + matrixWrite ----
// Resolution: 8 rows x 13 columns (row 0 = top, col 0 = left)

extern "C" void matrixBegin();
extern "C" void matrixWrite(const uint32_t* buf);

constexpr int ROWS = 8;
constexpr int COLS = 13;
constexpr int NUM_PIX = ROWS * COLS;     // 104 LEDs
constexpr uint16_t ROW_MASK = (1u << COLS) - 1;  // 13-bit mask

// Display state stored per-row as a 13-bit shift register (bit 12 = leftmost, bit 0 = rightmost)
static uint16_t rowsBits[ROWS] = {0};

// Buffer sent to the matrix (4 * 32 = 128 bits)
static uint32_t buf[4] = {0, 0, 0, 0};

// ------------------- 5x7 font (column-wise, LSB = top row) -------------------
// Each glyph is up to 5 columns wide, 7 rows tall (fits the 8-row display).
// For each column byte: bit0->row0 (top), ..., bit6->row6. Row7 is always off here.
// Space between characters = 1 blank column.
struct Glyph { uint8_t w; uint8_t col[5]; };

static const Glyph FONT_5x7[] = {
  // ASCII 32..90 (space to 'Z'); undefined chars become space
  /* 32 ' ' */ {3, {0x00,0x00,0x00,0x00,0x00}},
  /* 33 '!' */ {1, {0x5F,0x00,0x00,0x00,0x00}},
  /* 34 '\"'*/ {3, {0x03,0x00,0x03,0x00,0x00}},
  /* 35 '#' */ {5, {0x14,0x7F,0x14,0x7F,0x14}},
  /* 36 '$' */ {5, {0x24,0x2A,0x7F,0x2A,0x12}},
  /* 37 '%' */ {5, {0x23,0x13,0x08,0x64,0x62}},
  /* 38 '&' */ {5, {0x36,0x49,0x55,0x22,0x50}},
  /* 39 '\''*/ {1, {0x03,0x00,0x00,0x00,0x00}},
  /* 40 '(' */ {3, {0x1C,0x22,0x41,0x00,0x00}},
  /* 41 ')' */ {3, {0x41,0x22,0x1C,0x00,0x00}},
  /* 42 '*' */ {5, {0x14,0x08,0x3E,0x08,0x14}},
  /* 43 '+' */ {5, {0x08,0x08,0x3E,0x08,0x08}},
  /* 44 ',' */ {2, {0x40,0x20,0x00,0x00,0x00}},
  /* 45 '-' */ {5, {0x08,0x08,0x08,0x08,0x08}},
  /* 46 '.' */ {1, {0x40,0x00,0x00,0x00,0x00}},
  /* 47 '/' */ {5, {0x20,0x10,0x08,0x04,0x02}},
  /* 48 '0' */ {5, {0x3E,0x51,0x49,0x45,0x3E}},
  /* 49 '1' */ {3, {0x42,0x7F,0x40,0x00,0x00}},
  /* 50 '2' */ {5, {0x62,0x51,0x49,0x49,0x46}},
  /* 51 '3' */ {5, {0x22,0x49,0x49,0x49,0x36}},
  /* 52 '4' */ {5, {0x18,0x14,0x12,0x7F,0x10}},
  /* 53 '5' */ {5, {0x2F,0x49,0x49,0x49,0x31}},
  /* 54 '6' */ {5, {0x3E,0x49,0x49,0x49,0x32}},
  /* 55 '7' */ {5, {0x01,0x71,0x09,0x05,0x03}},
  /* 56 '8' */ {5, {0x36,0x49,0x49,0x49,0x36}},
  /* 57 '9' */ {5, {0x26,0x49,0x49,0x49,0x3E}},
  /* 58 ':' */ {1, {0x14,0x00,0x00,0x00,0x00}},
  /* 59 ';' */ {2, {0x40,0x34,0x00,0x00,0x00}},
  /* 60 '<' */ {4, {0x08,0x14,0x22,0x41,0x00}},
  /* 61 '=' */ {5, {0x14,0x14,0x14,0x14,0x14}},
  /* 62 '>' */ {4, {0x41,0x22,0x14,0x08,0x00}},
  /* 63 '?' */ {5, {0x02,0x01,0x59,0x09,0x06}},
  /* 64 '@' */ {5, {0x3E,0x41,0x5D,0x55,0x1E}},
  /* 65 'A' */ {5, {0x7E,0x11,0x11,0x11,0x7E}},
  /* 66 'B' */ {5, {0x7F,0x49,0x49,0x49,0x36}},
  /* 67 'C' */ {5, {0x3E,0x41,0x41,0x41,0x22}},
  /* 68 'D' */ {5, {0x7F,0x41,0x41,0x22,0x1C}},
  /* 69 'E' */ {5, {0x7F,0x49,0x49,0x49,0x41}},
  /* 70 'F' */ {5, {0x7F,0x09,0x09,0x09,0x01}},
  /* 71 'G' */ {5, {0x3E,0x41,0x49,0x49,0x7A}},
  /* 72 'H' */ {5, {0x7F,0x08,0x08,0x08,0x7F}},
  /* 73 'I' */ {3, {0x41,0x7F,0x41,0x00,0x00}},
  /* 74 'J' */ {5, {0x20,0x40,0x41,0x3F,0x01}},
  /* 75 'K' */ {5, {0x7F,0x08,0x14,0x22,0x41}},
  /* 76 'L' */ {5, {0x7F,0x40,0x40,0x40,0x40}},
  /* 77 'M' */ {5, {0x7F,0x02,0x0C,0x02,0x7F}},
  /* 78 'N' */ {5, {0x7F,0x04,0x08,0x10,0x7F}},
  /* 79 'O' */ {5, {0x3E,0x41,0x41,0x41,0x3E}},
  /* 80 'P' */ {5, {0x7F,0x09,0x09,0x09,0x06}},
  /* 81 'Q' */ {5, {0x3E,0x41,0x51,0x21,0x5E}},
  /* 82 'R' */ {5, {0x7F,0x09,0x19,0x29,0x46}},
  /* 83 'S' */ {5, {0x26,0x49,0x49,0x49,0x32}},
  /* 84 'T' */ {5, {0x01,0x01,0x7F,0x01,0x01}},
  /* 85 'U' */ {5, {0x3F,0x40,0x40,0x40,0x3F}},
  /* 86 'V' */ {5, {0x1F,0x20,0x40,0x20,0x1F}},
  /* 87 'W' */ {5, {0x7F,0x20,0x18,0x20,0x7F}},
  /* 88 'X' */ {5, {0x63,0x14,0x08,0x14,0x63}},
  /* 89 'Y' */ {5, {0x07,0x08,0x70,0x08,0x07}},
  /* 90 'Z' */ {5, {0x61,0x51,0x49,0x45,0x43}},
};

static inline const Glyph& glyphFor(char c) {
  uint8_t uc = (uint8_t)c;
  if (uc < 32 || uc > 90) uc = 32; // unsupported -> space
  return FONT_5x7[uc - 32];
}

// ------------------- helpers -------------------

// Shift the whole display left by one column and insert one new column at the right.
// colBits: bit0=top row pixel, bit6=row6. (row7 stays 0 for this 5x7 font, but you can use it)
static void pushColumn(uint8_t colBits) {
  for (int r = 0; r < ROWS; r++) {
    uint16_t bit = (colBits >> r) & 0x1;
    rowsBits[r] = uint16_t(((rowsBits[r] << 1) | bit) & ROW_MASK);
  }
}

// Convert rowsBits[] (our 8×13 state) into 4×uint32 buffer bits, row-major, left→right, top→bottom.
// NOTE: If your hardware expects a different packing, adapt ONLY this function.
static void updateBufFromRows() {
  buf[0] = buf[1] = buf[2] = buf[3] = 0;
  int idx = 0;
  for (int r = 0; r < ROWS; r++) {
    for (int c = 0; c < COLS; c++) {
      int on = (rowsBits[r] >> (COLS - 1 - c)) & 1; // (leftmost is bit 12)
      if (on) {
        int w = idx / 32;
        int b = idx % 32;
        buf[w] |= (1UL << b);
      }
      idx++;
    }
  }
}

// Push N blank columns (for leading/trailing spacing)
static void pushBlanks(int n, int speed_ms) {
  for (int i = 0; i < n; i++) {
    pushColumn(0x00);
    updateBufFromRows();
    matrixWrite(buf);
    delay(speed_ms);
  }
}

static void scrollText(const char* msg, int speed_ms, int space_cols = 1) {
  // lead-in blanks so text enters from the right
  pushBlanks(COLS, speed_ms);

  for (const char* p = msg; *p; ++p) {
    const Glyph& g = glyphFor(*p);
    for (int i = 0; i < g.w; i++) {
      pushColumn(g.col[i]);
      updateBufFromRows();
      matrixWrite(buf);
      delay(speed_ms);
    }
    for (int s = 0; s < space_cols; s++) {
      pushColumn(0x00);
      updateBufFromRows();
      matrixWrite(buf);
      delay(speed_ms);
    }
  }

  // trail-out blanks so text fully exits left side
  pushBlanks(COLS, speed_ms);
}

// ------------------- Arduino entry points -------------------

void setup() {
  matrixBegin();

  // Clear display state
  for (int r = 0; r < ROWS; r++) rowsBits[r] = 0;
  updateBufFromRows();
  matrixWrite(buf);

  // Your message here (ALL CAPS recommended with this minimal font)
  const char* message = "HELLO, WORLD!";
  const int speed_ms = 60;    // smaller = faster scroll
  const int spacing  = 1;     // blank columns between characters

  scrollText(message, speed_ms, spacing);

  // Optionally loop forever:
  // while (true) { scrollText(message, speed_ms, spacing); }
}

void loop() {
  // intentionally empty; we ran once in setup()
}

danpeirce · December 19, 2025, 5:29pm

Why not just convert the number to a string?

int sensorValue = 123;
String myString = String(sensorValue);

Edit:

I modified an IDE 2 example that sends a string to the LED matrix and scrolls it. The modification is it includes a countdown from 100.

#include "ArduinoGraphics.h"
#include "Arduino_LED_Matrix.h"

Arduino_LED_Matrix matrix;

int count;

void setup() {
  matrix.begin();
  matrix.textFont(Font_5x7);
  matrix.textScrollSpeed(100);
  matrix.clear();
  //Serial.begin(115200);
  count = 100;
}

void loop() {
  // Roll a string using ArduinoGraphics
  matrix.beginText(0, 1, 127, 0, 0); // X, Y, then R, G, B
  matrix.print(" count=" + String(count) + "  ");
  matrix.endText(SCROLL_LEFT);
  if (count > 0) count--; 
}

xfpd · December 20, 2025, 3:09pm

int value = 231;

void setup() {
  Serial.begin(115200);

  int cent = value / 100;
  value -= cent * 100;

  int tens = value / 10;
  value -= tens * 10;

  int ones = value;

  Serial.println(cent);
  Serial.println(tens);
  Serial.println(ones);
}

void loop() {
}

Result:

2
3
1

... hmm... but it looks like you want to print all the alphanu... just take their ASCII value and calculate which bitmap you need.

KurtE · December 26, 2025, 12:29am

I display strings on it in one of my modified apps

Would display more but not at machine, but it is contained in the file

github.com/KurtE/Arduino_UNO_Q

ArduinoApps/weather2/sketch/sketch.ino

main


      
              } else if (cur_precip > 10) {
                sprintf(buffer, ".%d", cur_precip % 100);
              } else {
                sprintf(buffer, ".0%d", cur_precip % 100);
              }
              display_string(buffer);
              delay(2000);
            }
          }
          
          void display_string(char* buffer) {
            Monitor.write(buffer);
            matrix.beginDraw();
            int cch = strlen(buffer);
            if (cch <= 2) {
              matrix.textFont(Font_5x7);
              int x_start = (13 - cch * 5) / 2;
              matrix.text(buffer, (x_start < 0) ? 0 : x_start, 1);
            } else {
              matrix.textFont(Font_4x6);
              if ((cch == 4) && (buffer[0] == '0') && (buffer[1] == '.')) {

petersin · January 5, 2026, 3:02pm

does not work, i cant find it in libraries.

xfpd · January 5, 2026, 3:17pm

If you can not find it on your system IDE...

You can find it on github (and install it)...

KurtE · January 5, 2026, 3:53pm

Which IDE?

If you are using Arduino IDE, you should be able to install it from the library manager

If you are using APP Lab - There is an issue that it does not currently show up in
the Libraries list, is it marked with specific Architectures...
More in the post:
Why can't I add the ArduinoGraphics library in Arduino App Lab? - UNO Family / UNO Q - Arduino Forum

Note: I issued a PR on that library to mark it as: *
which was merged in today. Not sure how long before they release a new version
of the library, and then at some point it should be then included in the list shown
in the App lab. But until then there are instructions on that other thread on
how to manually add it to your sketch.

danpeirce · January 5, 2026, 6:51pm

I did test it before posting. Note that it was uploaded from Arduino IDE and not App Lab.

EDIT:

After reading this post I have successfully run it in App Lab.

petersin · January 5, 2026, 10:18pm

indeed i am using App Lab.

petersin · January 5, 2026, 10:22pm

thank you

Topic		Replies	Views
I would like to display a text on Arduino Uno Q led matrix UNO Q	15	161	January 9, 2026
UNO-Q - utiliser un tableau ASCII pour la fonction matrixWrite() Le bar	21	223	January 3, 2026
Basic matrix test sketch for Arduino IDE UNO Q	8	297	November 25, 2025
[SOLVED] Arduino Uno mit LED Matrix Deutsch	56	559	April 24, 2025
Text Scrolling with Dot Matrix 8x8 and MAX7219 LEDs and Multiplexing	16	34959	March 16, 2025

How to display a number on the UNO Q's built-in LED matrix, please?

Related topics