I am attempting to do one thing I feel can be easy. I would wish to learn the enter of a electret microphone board and replace the Adafruit 24-segment LED Bar Graph. I bought every particular person merchandise working completely: I can learn the enter of the microphone on the analog pin and I can replace the LED bar graph utilizing I2C.

The difficulty happens after I tried to mix the 2 ideas. When the bard graph will get up to date, the analog enter reads HIGH (1023) and by no means adjustments. I used my normal debug methodology and commented out code till the issue went away, so I’ve narrowed down the problem to a single line of code (proper on the finish). When the bar.writeDisplay known as the analog enter perpetually reads 1023.

If I remark out that one line of code and re-upload my sketch the readings (within the Serial Monitor) are as anticipated (decrease when its quiet and better when its loud).

Below the hood Adafruit is utilizing the Wire library.

I am no good at wiring diagrams, however this is what I’ve:

RoboDyn Mega 2560 Professional (Embed)
5V, Gnd, SDA (20), SCL (21) to the LED Backpack
5V, Gnd, Out (A15/69)

That mentioned, I am comparatively assured this isn’t a wiring downside as all the things works till the software program will get ahold of it.

#embrace <Wire.h>
#embrace <Adafruit_GFX.h>
#embrace "Adafruit_LEDBackpack.h"

Adafruit_24bargraph bar = Adafruit_24bargraph();

int pin = 69;
unsigned int sampleWindow = 50; // millis
unsigned int maxScale = 24;

void setup() {
  Serial.start(9600);
  bar.start(0x70);  // cross within the handle
}

void loop() {
  unsigned lengthy startMillis = millis();  // Begin of pattern window
  unsigned int peakToPeak = 0;   // peak-to-peak stage
  unsigned int pattern;
  unsigned int signalMax = 0;
  unsigned int signalMin = 1024;
  whereas (millis() - startMillis < sampleWindow) {
    pattern = analogRead(pin); 
    if (pattern < 1024) {  // toss out spurious readings
      if (pattern > signalMax) {
        signalMax = pattern;  // save simply the max ranges
      }
      else if (pattern < signalMin) {
        signalMin = pattern;  // save simply the min ranges
      }
    }
  }
  peakToPeak = signalMax - signalMin;  
  int displayPeak = map(peakToPeak, 0, 1023, 0, maxScale); // map 1v p-p stage to the max scale of the show
  Serial.print("mic: "); Serial.print(peakToPeak); Serial.print(" "); Serial.println(displayPeak);
  for (uint8_t b = 0; b < 24; b++) {
    if (b <= displayPeak) {
      int c = LED_GREEN;
      if (b >= 20) {
        c = LED_RED;
      }
      else if (b >= 16) {
        c = LED_YELLOW;
      }
      bar.setBar(23 - b, c);
    }
    else {
      bar.setBar(23 - b, LED_OFF);
    }
    //bar.writeDisplay(); // <------- THIS LINE
  }
}

UPDATE: It seems to be one thing with the way in which Adafruit makes use of the Wire library. I’ve an identical downside after I use the Adafruit 7-segment library, after I use their MCP23017 library.

However it’s wiring associated too. If I uncomment the commented out line above however disconnect the I2C system the analog enter begins working once more.

Yet another factor I’ve found: it depends upon what number of lights are lit on the I2C board. As soon as all of the lights are lit, the analog pin reads full. When solely a few lights are lit, the values are decrease. It’s just like the voltage going into the mic is greater when the lights are brighter.

For curiosity sake, I attempted the identical factor on a special Arduino (Adafruit Feather 32u4) with the identical consequence (so it is not my Arduino).