Faulty LED on R4 WiFi?

Official Hardware UNO Family UNO R4 WiFi
1

I believe my R4 WiFi came with a faulty LED (or faulty something else) that is preventing one of the LEDs in the matrix from functioning properly. Is there anything I can do to fix this?

When attempting to turn on led[2][7] (3rd row, 8th column), the following LEDs turn on at about 50% brightness:

  • led[0][1]
  • led[0][3]
  • led[0][7]
  • led[1][1]
  • led[1][9]
  • led[2][9]
  • led[2][11]
  • led[3][1]
  • led[3][3]
  • led[3][5]
  • led[3][7]
  • led[4][6]
  • led[4][9]
  • led[5][8]
  • led[6][1]
  • led[7][0]

Here are photos of the board with just led[2][7] on and with all LEDs on.

IMG_3310
IMG_33101280×960 301 KB

IMG_3312
IMG_33121280×960 106 KB

Thank you in advance!

2

Welcome to the forum

Please post a sketch that illustrates the problem, using code tags when you do

3

Sure thing.

sketch_a.ino will flash like the first image I posted. The list of 16 LEDs will flash dimly, and the desired LED (frame[2][7]) stays dark.

// sketch_a.ino
#include "Arduino_LED_Matrix.h"

ArduinoLEDMatrix matrix;

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

uint8_t frame[8][12] = {
  { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }
};

void off() {
  // Faulty LED off
  frame[2][7] = 0;
}

void on() {
  // Faulty LED on
  frame[2][7] = 1;
}

void loop()
{
  off();

  matrix.renderBitmap(frame, 8, 12);

  delay(300);
  on();

  matrix.renderBitmap(frame, 8, 12);
  delay(300);
}

sketch_b.ino results in the second photo. All LEDs are illuminated except frame[2][7], despite the sketch specifying all LEDs should be lit.

// sketch_b.ino
#include "Arduino_LED_Matrix.h"

ArduinoLEDMatrix matrix;

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

uint8_t frame[8][12] = {
  { 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 },
  { 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 },
  { 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 },
  { 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 },
  { 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 },
  { 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 },
  { 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 },
  { 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 }
};

void loop()
{
  matrix.renderBitmap(frame, 8, 12);
}

I should also note that the demo program that came with the R4 also exhibited this issue. The "large heart" part of the demo, as well as the Tetris portion, both attempt the activate the problem LED, with the same result (desired LED stays dark, subset of 16 other LEDs light up slightly).

4

Hi @scottkolo. I'm sorry about the problem with your UNO R4 WiFi board. Please contact the seller you purchased the board from about the defect. If you purchased it from the Arduino Store, you can use this contact form:

https://www.arduino.cc/en/contact-us

5

Okay, thank you! I'll follow up with Digi-Key.

6

Thanks for posting the sketches

I am sure that it will be no consolation to you, but my board works fine !

Good luck getting a refund or replacement